text:
2. Data and methods
a. Model design
b. Experimental design
c. Definitions
a. Control
b. Sensitivity to the mean wind
c. Sensitivity to the low-level shear
d. Variations in the thermodynamic environment
1) Lee low-level cooling
2) Lee low-level drying
4. Discussion and conclusions
Bell, G. D., and L. F. Bosart, 1988: Appalachian cold-air damming. Mon. Wea. Rev., 116, 137–161.
Bell, G. D., and L. F. Bosart, 1988: Appalachian cold-air damming. Mon. Wea. Rev., 116, 137–161.)| false
Bryan, G. H., and M. J. Fritsch, 2002: A benchmark simulation for moist nonhydrostatic numerical models. Mon. Wea. Rev., 130, 2917–2928.
Bryan, G. H., and M. J. Fritsch, 2002: A benchmark simulation for moist nonhydrostatic numerical models. Mon. Wea. Rev., 130, 2917–2928.)| false
Bryan, G. H., J. C. Wyngaard, and M. J. Fritsch, 2003: Resolution requirements for the simulation of deep moist convection. Mon. Wea. Rev., 131, 2394–2416.
Bryan, G. H., J. C. Wyngaard, and M. J. Fritsch, 2003: Resolution requirements for the simulation of deep moist convection. Mon. Wea. Rev., 131, 2394–2416.)| false
Bryan, G. H., J. C. Knievel, and M. D. Parker, 2006: A multimodel assessment of RKW theory's revelance to squall-line characteristics. Mon. Wea. Rev., 134, 2772–2792.
Bryan, G. H., J. C. Knievel, and M. D. Parker, 2006: A multimodel assessment of RKW theory's revelance to squall-line characteristics. Mon. Wea. Rev., 134, 2772–2792.)| false
Chen, G. J. T., and H. C. Chou, 1993: General characteristics of squall lines observed in TAMEX. Mon. Wea. Rev., 121, 726–733.
Chen, G. J. T., and H. C. Chou, 1993: General characteristics of squall lines observed in TAMEX. Mon. Wea. Rev., 121, 726–733.)| false
Chen, S.-H., and Y.-L. Lin, 2005: Effects of moist Froude number and CAPE on a conditionally unstable flow over a mesoscale mountain ridge. J. Atmos. Sci., 62, 331–350.
Chen, S.-H., and Y.-L. Lin, 2005: Effects of moist Froude number and CAPE on a conditionally unstable flow over a mesoscale mountain ridge. J. Atmos. Sci., 62, 331–350.)| false
Chu, C.-M., and Y.-L. Lin, 2000: Effects of orography on the generation and propagation of mesoscale convective systems in a two-dimensionally conditionally unstable flow. J. Atmos. Sci., 57, 3817–3837.
Chu, C.-M., and Y.-L. Lin, 2000: Effects of orography on the generation and propagation of mesoscale convective systems in a two-dimensionally conditionally unstable flow. J. Atmos. Sci., 57, 3817–3837.)| false
Cohen, A. E., M. C. Coniglio, S. F. Corfidi, and S. J. Corfidi, 2007: Discrimination of mesoscale convective system environments using sounding observations. Wea. Forecasting, 22, 1045–1062.
Cohen, A. E., M. C. Coniglio, S. F. Corfidi, and S. J. Corfidi, 2007: Discrimination of mesoscale convective system environments using sounding observations. Wea. Forecasting, 22, 1045–1062.)| false
Coniglio, M. C., D. J. Stensrud, and L. J. Wicker, 2006: Effects of upper-level shear on the structure and maintenance of strong quasi-linear mesoscale convective systems. J. Atmos. Sci., 63, 1231–1252.
Coniglio, M. C., D. J. Stensrud, and L. J. Wicker, 2006: Effects of upper-level shear on the structure and maintenance of strong quasi-linear mesoscale convective systems. J. Atmos. Sci., 63, 1231–1252.)| false
Coniglio, M. C., H. E. Brooks, S. J. Weiss, and S. F. Corfidi, 2007: Forecasting the maintenance of quasi-linear mesoscale convective systems. Wea. Forecasting, 22, 556–570.
Coniglio, M. C., H. E. Brooks, S. J. Weiss, and S. F. Corfidi, 2007: Forecasting the maintenance of quasi-linear mesoscale convective systems. Wea. Forecasting, 22, 556–570.)| false
Durran, D. R., 1986: Another look at downslope windstorms. Part I: The development of analogs to supercritical flow in an infinitely deep, continuously stratified fluid. J. Atmos. Sci., 43, 2527–2543.
Durran, D. R., 1986: Another look at downslope windstorms. Part I: The development of analogs to supercritical flow in an infinitely deep, continuously stratified fluid. J. Atmos. Sci., 43, 2527–2543.)| false
Frame, J., and P. Markowski, 2006: The interaction of simulated squall lines with idealized mountain ridges. Mon. Wea. Rev., 134, 1919–1941.
Frame, J., and P. Markowski, 2006: The interaction of simulated squall lines with idealized mountain ridges. Mon. Wea. Rev., 134, 1919–1941.)| false
Gale, J. J., W. A. Gallus Jr., and K. A. Jungbluth, 2002: Toward improved prediction of mesoscale convective system dissipation. Wea. Forecasting, 17, 856–872.
Gale, J. J., W. A. Gallus Jr., and K. A. Jungbluth, 2002: Toward improved prediction of mesoscale convective system dissipation. Wea. Forecasting, 17, 856–872.)| false
Keighton, S., J. Jackson, J. Guyer, and J. Peters, 2007: A preliminary analysis of severe quasi-linear mesoscale convective systems crossing the Appalachians. Preprints, 22nd Conf. on Weather Analysis and Forecasting, Park City, UT, Amer. Meteor. Soc., P2.18.
Keighton, S., J. Jackson, J. Guyer, and J. Peters, 2007: A preliminary analysis of severe quasi-linear mesoscale convective systems crossing the Appalachians. Preprints, 22nd Conf. on Weather Analysis and Forecasting, Park City, UT, Amer. Meteor. Soc., P2.18.)| false
Kessler, E., 1969: On the Distribution and Continuity of Water Substance in Atmospheric Circulations. Meteor. Monogr., No. 32, Amer. Meteor. Soc., 84 pp.
Kessler, E., 1969: On the Distribution and Continuity of Water Substance in Atmospheric Circulations. Meteor. Monogr., No. 32, Amer. Meteor. Soc., 84 pp.)| false
Kirkpatrick, J. C., E. W. McCaul Jr., and C. Cohen, 2007: The motion of simulated convective storms as a function of basic environmental parameters. Mon. Wea. Rev., 135, 3033–3051.
Kirkpatrick, J. C., E. W. McCaulJr., and C. Cohen, 2007: The motion of simulated convective storms as a function of basic environmental parameters. Mon. Wea. Rev., 135, 3033–3051.)| false
Letkewicz, C. E., and M. D. Parker, 2010: Forecasting the maintenance of mesoscale convective systems crossing the Appalachian Mountains. Wea. Forecasting, 25, 1179–1195.
Letkewicz, C. E., and M. D. Parker, 2010: Forecasting the maintenance of mesoscale convective systems crossing the Appalachian Mountains. Wea. Forecasting, 25, 1179–1195.)| false
McCaul, E. W., Jr., and C. Cohen, 2004: The initiation, longevity and morphology of simulated convective storms as a function of free tropospheric relative humidity. Preprints, 22nd Conf. on Severe Local Storms, Hyannis, MA, Amer. Meteor. Soc., 8A.5.
McCaul, E. W., Jr., and C. Cohen, 2004: The initiation, longevity and morphology of simulated convective storms as a function of free tropospheric relative humidity. Preprints, 22nd Conf. on Severe Local Storms, Hyannis, MA, Amer. Meteor. Soc., 8A.5.)| false
Miglietta, M. M., and R. Rotunno, 2009: Numerical simulations of conditionally unstable flows over a mountain ridge. J. Atmos. Sci., 66, 1865–1885.
Miglietta, M. M., and R. Rotunno, 2009: Numerical simulations of conditionally unstable flows over a mountain ridge. J. Atmos. Sci., 66, 1865–1885.)| false
Munoz, L. A., and R. B. Wilhelmson, 1993: Structure and evolution of thunderstorms encountering temperature inversions. Preprints, 17th Conf. Severe Local Storms, St. Louis, MO, Amer. Meteor. Soc., 247–251.
Munoz, L. A., and R. B. Wilhelmson, 1993: Structure and evolution of thunderstorms encountering temperature inversions. Preprints, 17th Conf. Severe Local Storms, St. Louis, MO, Amer. Meteor. Soc., 247–251.)| false
Parker, M. D., 2008: Response of simulated convective squall lines to low-level cooling. J. Atmos. Sci., 65, 1323–1341.
Parker, M. D., 2008: Response of simulated convective squall lines to low-level cooling. J. Atmos. Sci., 65, 1323–1341.)| false
Parker, M. D., and R. H. Johnson, 2004: Simulated convective lines with leading precipitation. Part I: Governing dynamics. J. Atmos. Sci., 61, 1637–1655.
Parker, M. D., and R. H. Johnson, 2004: Simulated convective lines with leading precipitation. Part I: Governing dynamics. J. Atmos. Sci., 61, 1637–1655.)| false
Parker, M. D., and D. A. Ahijevych, 2007: Convective episodes in the east-central United States. Mon. Wea. Rev., 135, 3707–3727.
Parker, M. D., and D. A. Ahijevych, 2007: Convective episodes in the east-central United States. Mon. Wea. Rev., 135, 3707–3727.)| false
Reeves, H. D., and Y.-L. Lin, 2007: The effects of a mountain on the propagation of a preexisting convective system for blocked and unblocked flow regimes. J. Atmos. Sci., 64, 2401–2421.
Reeves, H. D., and Y.-L. Lin, 2007: The effects of a mountain on the propagation of a preexisting convective system for blocked and unblocked flow regimes. J. Atmos. Sci., 64, 2401–2421.)| false
Rotunno, R., J. B. Klemp, and M. L. Weisman, 1988: A theory for strong, long-lived squall lines. J. Atmos. Sci., 45, 463–485.
Rotunno, R., J. B. Klemp, and M. L. Weisman, 1988: A theory for strong, long-lived squall lines. J. Atmos. Sci., 45, 463–485.)| false
Thompson, G., R. M. Rasmussen, and K. Manning, 2004: Explicit forecasts of winter precipitation using an improved bulk microphysics scheme. Part I: Description and sensitivity analysis. Mon. Wea. Rev., 132, 519–542.
Thompson, G., R. M. Rasmussen, and K. Manning, 2004: Explicit forecasts of winter precipitation using an improved bulk microphysics scheme. Part I: Description and sensitivity analysis. Mon. Wea. Rev., 132, 519–542.)| false
Weisman, M. L., 1993: The genesis of severe, long-lived bow echoes. J. Atmos. Sci., 50, 645–670.
Weisman, M. L., 1993: The genesis of severe, long-lived bow echoes. J. Atmos. Sci., 50, 645–670.)| false
Weisman, M. L., and J. B. Klemp, 1982: The dependence of numerically simulated convective storms on vertical wind shear and buoyancy. Mon. Wea. Rev., 110, 504–520.
Weisman, M. L., and J. B. Klemp, 1982: The dependence of numerically simulated convective storms on vertical wind shear and buoyancy. Mon. Wea. Rev., 110, 504–520.)| false
Weisman, M. L., and R. Rotunno, 2004: "A theory for strong long-lived squall lines" revisited. J. Atmos. Sci., 61, 361–382.
Weisman, M. L., and R. Rotunno, 2004: "A theory for strong long-lived squall lines" revisited. J. Atmos. Sci., 61, 361–382.)| false
Weisman, M. L., J. B. Klemp, and R. Rotunno, 1988: Structure and evolution of numerically simulated squall lines. J. Atmos. Sci., 45, 1990–2013.
Weisman, M. L., J. B. Klemp, and R. Rotunno, 1988: Structure and evolution of numerically simulated squall lines. J. Atmos. Sci., 45, 1990–2013.)| false
Weisman, M. L., W. C. Skamarock, and J. B. Klemp, 1997: The resolution dependence of explicitly modeled convective systems. Mon. Wea. Rev., 125, 527–548.
Weisman, M. L., W. C. Skamarock, and J. B. Klemp, 1997: The resolution dependence of explicitly modeled convective systems. Mon. Wea. Rev., 125, 527–548.)| false
Homogeneous base-state (a) thermodynamic and u-wind (mountain perpendicular) profiles testing the sensitivity to (b) the mean wind, (c) the low-level shear, and (d) the low-level shear with a constant mean wind. The thermodynamic profile in (a) is adapted from Weisman and Klemp (1982), with a constant boundary layer mixing ratio of 14 g kg−1.
Hovmöller diagrams comparing (left) along-line averaged surface simulated reflectivity, (middle) θ ′ (K), and (right) lowest model level vertical velocity w (m s−1) for the (from top to bottom) no-terrain, control, increased mean wind +5 m s−1, and decreased mean wind −5 m s−1 simulations. The x axis in each represents the distance from the mountain peak (at x = 0) in km and the y axis displays simulation time in h. (f) The arrow points to a feature discussed in the text.
Evolution of the surface simulated reflectivity for the control wind profile (a)–(d) without and (e)–(h) with terrain over time, as noted. The thick black contour represents −2-K θ ′ and denotes the position of the outflow boundary.
Along-line averaged vertical cross sections of vertical velocity w (m s−1; shaded) and θ ′ (K; contoured) over time (as noted), computed relative to the objectively determined surface gust front location at every y point for the control simulation with terrain. The x axis indicates the distance from the leading edge of the cold pool in km.
Illustration of the development of the hydraulic jump in the environmental flow leading to a wave train using (a) a Hovmöller diagram of surface u wind (m s−1; shaded) and 3-km vertical velocity w (m s−1; contoured) and (b),(c) vertical cross sections at t = 120 and t = 250 min, respectively, of vertical velocity w (m s−1; shaded) and θ ′ (K; contoured).
Comparison of control simulations with (left) ice microphysics and (right) rain-only microphysics, using (a),(b) Hovmöller diagrams of along-line averaged surface simulated reflectivity; (c),(d) plan views of θe (K, shaded) and simulated reflectivity (contoured every 10 dBZ); and (e),(f) vertical cross sections of along-line averaged θe (shaded) and u wind (m s−1).
Hovmöller diagrams of the along-line average of the maximum vertical velocity w (m s−1) for the (a) control and (b) increased mean wind +5 m s−1 simulations. Smoothing has been applied to the field to account for insufficient time resolution in the output, allowing it to appear more continuous.
As in Fig. 2, but for the simulations varying the low-level shear.
(a) Theoretical density current speed C and (b) C/ΔU computed at several locations upstream and downstream of the mountain peak (x = 0 km) for the simulations with varying low-level shear.
As in Fig. 4, but for the simulation with low-level shear decreased by −5 m s−1.
Hovmöller diagrams comparing (a),(b) along-line averaged surface simulated reflectivity and (c),(d) θ ′ (K) for the simulations with the same mean wind but varying low-level shear. The x axis in each represents the distance from the mountain peak (at x = 0) in km and the y axis displays simulated time in h.
Skew T–logp diagrams of the modified lee thermodynamic environments. Modifications include (a) cooling the surface 6 K (dashed) or 12 K (black), and (b) drying the low-levels to a constant 11 g kg−1 (black) or the average observed mixing ratio of all cases in LP10 (dashed).
Comparison of the simulations cooling the surface in the lee by 6 and 12 K using Hovmöller diagrams of (a),(b) along-line averaged surface simulated reflectivity and (c),(d) θ ′ (K); and (e),(f) instantaneous along-line averaged cross sections of potential temperature (alternately shaded every 3 K from dark to light, starting at 291 K) and vertical velocity (m s−1, contoured).
Along-line averaged cross sections computed relative to the objectively determined surface gust front location (as in Fig. 4) comparing the (a) control, (b) surface cooling in the lee by 6 K, and (c) surface cooling in the lee by 12-K simulations. Vertical velocity w (m s−1) and CAPE are contoured (J kg−1; thick and thin contours, respectively), while θ ′ (K) is shaded. Each cross section is representative of the time at which the cold pool reached 60 km downstream of the peak of the barrier. The x axis indicates the distance from the leading edge of the cold pool in km.
Comparison of the simulations drying the lowest 3 km in the lee to the average observed moisture profile of all cases in LP10 with (left) the control and (right) increased mean wind +5 m s−1 wind profiles. (a),(b) The along-line averaged surface simulated reflectivity and (c),(d) the along-line average of the maximum vertical velocity w (m s−1).
Hovmöller diagrams comparing the simulations drying the lowest 3 km in the lee to the average observed moisture profile of all cases in LP10 with an increased mean wind +5 m s−1 both (left) without and (right) with terrain. (a),(b) The along-line averaged surface simulated reflectivity; (c),(d) the along-line averaged surface θ ′ (K); and (e),(f) the along-line average of the maximum vertical velocity w (m s−1).
Impact of Environmental Variations on Simulated Squall Lines Interacting with Terrain
Casey E. Letkewicz
Casey E. LetkewiczNorth Carolina State University, Raleigh, North Carolina
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Matthew D. Parker
Matthew D. ParkerNorth Carolina State University, Raleigh, North Carolina
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https://doi.org/10.1175/2011MWR3635.1
The complex evolution of convective systems crossing (or attempting to cross) mountainous terrain represents a substantial forecasting challenge. This study examines the processes associated with environments of "crossing" squall lines (which were able to redevelop strong convection in the lee of a mountain barrier) and "noncrossing" squall lines (which were not able to redevelop strong convection downstream of the barrier). In particular, numerical simulations of mature convective systems crossing idealized terrain roughly approximating the Appalachian Mountains were used to test the first-order impact of variations in the vertical wind profile upon system maintenance.
By itself, the wind profile showed no ability to uniquely discriminate between simulated crossing and noncrossing squall lines; each test revealed a similar pattern of orographic enhancement, suppression, and lee reinvigoration in which a hydraulic jump deepened the system's cold pool and renewed the low-level lifting. Increasing the mean wind led to greater enhancement of vertical velocities on the windward side of the barrier and greater suppression on the lee side. Variations in the low-level shear influenced the temperature and depth of the outflow, which in turn altered the lifting along the system's gust front. However, in all of the wind profile tests, convection redeveloped in the lee. Additional simulations explored more marginal environments in which idealized low-level cooling or drying stabilized the downstream environment. In most such tests, the systems weakened but the presence of CAPE aloft still enabled the systems to survive in the lee. However, the combination of a stronger mean wind with diminished CAPE and increased convective inhibition (CIN) was ultimately found to eliminate downstream redevelopment and produce a noncrossing mesoscale convective system (MCS). Within these experiments, the ability of a squall line to cross a barrier similar to the Appalachians is primarily tied to the characteristics of the downstream thermodynamic environment; however, as the lee thermodynamic environment becomes less favorable, the mean wind exerts a greater influence on system intensity and redevelopment.
Corresponding author address: Casey E. Letkewicz, Department of Marine, Earth, and Atmospheric Sciences, North Carolina State University, Campus Box 8208, Raleigh, NC 27695-8208. E-mail: celetkew@ncsu.edu
Keywords: Orographic effects; Convective storms; Squall lines; Cloud parameterizations; Thermodynamics
Forecasting the maintenance of mesoscale convective systems (MCSs) is a well-known operational problem and has served as the focus of numerous studies (e.g., Gale et al. 2002; Coniglio et al. 2006, 2007). Such studies were often performed with the goal of better understanding the fundamental dynamics of MCSs as well as anticipating their potential hazards. For simplicity, few of these studies accounted for the impacts of topography, even though organized convective systems are known to encounter complex terrain (e.g., Chen and Chou 1993; Keighton et al. 2007). Explorations of topography and organized convection have increased in recent years, including both observationally based (e.g., Keighton et al. 2007; Parker and Ahijevych 2007) and modeling-based studies (e.g., Frame and Markowski 2006, hereafter FM06; Reeves and Lin 2007).
Letkewicz and Parker (2010, hereafter LP10) built upon the work of Keighton et al. (2007) by examining 40 squall lines observed to encounter the Appalachian Mountains. The squall lines were categorized based on whether or not they were able to continue to produce severe weather in the lee of the terrain. "Crossing" cases were associated with severe weather reports both upstream and downstream of the mountains, while "noncrossing" cases only produced severe weather upstream of the barrier, and often dissipated upon encountering the terrain (Keighton et al. 2007). Although the synoptic-scale upper-level flow patterns were similar between case types, analysis of representative inflow soundings for 20 crossing and 20 noncrossing cases (both upstream and downstream of the Appalachians) revealed that their downstream environments were significantly different (LP10). This finding stands somewhat in contrast to previous research (e.g., Reeves and Lin 2007) that primarily studied upstream effects (i.e., blocking of the cold pool) of terrain on a convective system. LP10 found that crossing cases were characterized by downstream thermodynamic environments containing higher instability and lower convective inhibition, consistent with previous research on MCS maintenance (e.g., Coniglio et al. 2007; Cohen et al. 2007). This finding was also consistent with the conclusion by Keighton et al. (2007) that "crossers" are most common during the day and "noncrossers" are more common at night. LP10 recommended that forecasters assess the most-unstable parcel's convective available potential energy (MUCAPE) in the lee because it is the most general requirement for storms to develop and be maintained (including elevated storms) and, when paired with the most-unstable parcel's convective inhibition (MUCIN), it correctly diagnosed a majority of the cases in the LP10 dataset.
Here, the authors take it as a fairly elementary conclusion that at least modest CAPE and small convective inhibition (CIN) are necessary for convective maintenance. However, in contrast to other MCS maintenance studies (e.g., Coniglio et al. 2007; Cohen et al. 2007), LP10 also found that the crossing cases moved into downstream environments typified by weaker vertical wind shear and a weaker mean wind. LP10 attempted to interpret this result in terms of the conceptual model of FM06, who described how topography impacts preexisting organized convection. Their idealized simulations showed that as squall lines traverse a barrier, they undergo orographic enhancement, followed by suppression, and then lee reinvigoration due to changes in the cold pool induced by the topography. As the system ascends the barrier, it undergoes orographic enhancement due to the upslope component of flow near the gust front. Then, as the system descends the barrier, the cold pool thins as the outflow becomes supercritical.1 This thinning of the cold pool adds to the lee suppression induced by ambient downslope flow and the sinking branch of an orographic gravity wave. When the cold pool reaches the base of the mountain in the lee, the outflow transitions back to the subcritical regime, suddenly slowing and deepening; this abrupt change in the depth of the fluid is known as a hydraulic jump, and its formation leads to subsequent restrengthening of the convection due to a stronger lift along the gust front.
In the context of the FM06 conceptual model, LP10 hypothesized that a weaker mean wind and less bulk shear downstream would promote MCS maintenance in a few ways. First, a weaker mean wind would induce weaker downslope flow in the lee, resulting in less lee suppression during the key stage when restrengthening must occur. The benefit of weaker bulk shear was interpreted in light of the squall-line maintenance theory of Rotunno et al. [1988, hereafter referred to as the Rotunno–Klemp–Weisman (RKW) theory]: less shear was hypothesized to provide a better balance with systems' weakened cold pools in the lee, resulting in stronger lifting. Finally, LP10 conjectured that stronger lee shear promotes greater entrainment into developing updrafts, thus suppressing convection in the lee. This effect was theorized to be more profound in the smaller-CAPE noncrosser environments.
Unfortunately, a wide spread in the observed wind profiles in LP10 made it difficult to ascertain the true predictive capability of the wind profile. Furthermore, the inherent correlation of the mean wind and bulk shear made it unclear which ingredient was the most dynamically relevant in the observations. Another unanswered question was whether or not the wind profile alone is sufficient to discriminate between crossing and noncrossing MCSs (or whether its predictive capability is dependent upon the thermodynamic environment). The primary goal of this study was to ascertain the role of the wind profile (if any) in maintaining organized convection that encounters terrain. This was accomplished through idealized modeling tests that varied the mean wind and low-level shear independently, both with and without corresponding modifications to the thermodynamic environment. Section 2 describes the model setup and experiments while section 3 discusses the results of each sensitivity test along with the relevant processes. Finally, section 4 concludes with a summary of the key findings and implications of this work.
This study employed version 1.14 of the Bryan Cloud Model (CM1; Bryan and Fritsch 2002), a three-dimensional nonhydrostatic numerical model, to simulate idealized squall lines. The horizontal grid spacing was 500 m and the vertical grid spacing was stretched from 150 m at the model surface to 500 m aloft. This grid spacing is a bit coarser than what Bryan et al. (2003) recommended for convection, but it is comparable to that used by FM06 in the vertical and finer in the horizontal. The grid spacing provided a reasonable depiction of system structure (e.g., Weisman et al. 1997), while also being affordable enough to permit a large number of experiments. The vertical grid reached 20 km in height with the upper 6 km serving as a Rayleigh damping layer. The periodic y dimension was 60 km in extent; the across-line x dimension was nominally 600 km, although this was increased for the faster-moving squall-line simulations. Line-end effects were eliminated by the periodic y dimension; the focus here was on the key convective-scale processes at work during the lee redevelopment stages of the simulated systems.
To preserve comparability between the present study and FM06, convection was initiated in the same manner, using a line thermal with a potential temperature perturbation θ ′ of +4 K on which random temperature perturbations of up to 0.1 K were imposed, ensuring the development of 3D motions. The horizontally homogeneous base-state environment was identical to FM06, utilizing an idealized thermodynamic profile (Weisman and Klemp 1982) and wind profile (used in many numerical studies of squall lines (e.g., Rotunno et al. 1988; Weisman et al. 1988; see Fig. 1). Variations applied to the base state are discussed in section 2b. Additional simulations were attempted using the composite observed soundings from LP10; however, in the present idealized horizontally homogeneous framework, long-lived mature convective systems were unable to be produced in such environments due to the hindering effects of dry air and CIN (e.g., Figs. 4 and 6 of LP10). Such issues are known to be common in idealized simulations of deep moist convection (e.g., Munoz and Wilhelmson 1993; McCaul and Cohen 2004; Kirkpatrick et al. 2007).
Citation: Monthly Weather Review 139, 10; 10.1175/2011MWR3635.1
A bell-shaped mountain barrier was specified by the following equation:
where h(x) represents the terrain height, H is the maximum height of the barrier (defined as 1 m in these simulations), xp represents the location of the peak, and a is the barrier's half-width (50 m). In FM06, the terrain was much narrower, with a scale more typical of an individual ridge within a mountain chain. However, because the present study was motivated by the findings in LP10, the focus was on maintenance of squall lines encountering a mountain chain of dimensions similar to the Appalachian Mountains. A number of tests were performed with different barrier widths and the impacts were found to be small compared to the environmental influences that served as the focus of this study. Because FM06 already discussed the impacts of barrier width on their similar simulations, such results are not reported in detail here. The idealized barrier was infinitely long in the y direction and had no y variations. Each simulated squall line was allowed to evolve and mature for 3 h before its cold pool reached the base of the terrain.
Precipitation microphysics were parameterized with the scheme of Thompson et al. (2004). The Coriolis force, surface physics, and radiation were neglected in order to isolate the key convective-scale dynamics. Real-world MCSs are potentially impacted by such processes, particularly as they pertain to the development of diurnally driven slope flows. However, before undertaking more complicated simulations, it was desirable to first isolate and understand the effects of varying the wind profile.
The sensitivity tests chosen for this study were motivated by the intriguing finding within LP10 that the wind profile is a statistically significant discriminator of crossers from noncrossers. Is the wind profile so important that it can be the deciding factor in environments with identical thermodynamic profiles? Clearly, if CAPE is zero then no convection is possible, regardless of the wind profile. However, it is unclear to what degree a noncrossing wind profile (i.e., a wind profile with stronger shear and mean wind) would suppress an MCS given the benefit of ample instability. To pursue this question, for the preponderance of the simulations the thermodynamic sounding was held fixed (Fig. 1a) while the wind profile was systematically varied (Figs. 1b–d). These experiments can be split into two categories: changes to the mean wind (Fig. 1b) and changes to the low-level shear (Fig. 1c). Since variations in shear inherently result in changes to the mean wind, further tests were performed that kept the mean wind in the lowest 2.5 km constant while changing the shear in that same layer (Fig. 1d). While previous studies have examined the behavior of precipitation systems encountering topography using changes to the base-state flow (e.g., Reeves and Lin 2007; Miglietta and Rotunno 2009), the current study used the FM06 conceptual model as a starting point and examined the sensitivities of this model to changes in the wind profile.
LP10 speculated that the wind profile would have a greater impact on the crossing process when the thermodynamic environment is less favorable. To quantify this, two types of experiments were performed. The first type introduced low-level cooling in the lee over the lowest 2 km AGL in the manner of Parker (2008), decreasing the surface temperature by 6 or 12 K. The lee cooling was achieved in each case by the time the squall line reached the peak of the mountain. The second type of experiment gradually modified the moisture profile in the lee by nudging it to a drier reference profile over time. As in the cooling simulations, the moisture modification was complete by the time the squall line reached the mountain peak. One set of tests decreased the boundary layer mixing ratio from 14 to 11 g kg−1 while another set of tests relaxed the 0–3-km moisture profile toward the averaged value of all LP10's observed cases. [Interested readers can look ahead to Fig. 12 in order to see skew T–logp diagrams from these cooling and drying experiments (the results are discussed in section 3d).]
Keighton et al. (2007) defined a crossing or noncrossing MCS based upon the production of severe weather reports in the lee of the mountains. Unfortunately, it is hard to produce a defendable metric for surface wind gusts or hail size in the present idealized model framework. Thus, a simple, objective definition of a crossing MCS was applied in this study. In the results and discussion that follows, a simulated squall line will be called a crosser if its along-line averaged simulated surface reflectivity is greater than 40 dBZ and its along-line averaged maximum vertical velocity is greater than 5 m s−1 in the lee of the barrier. Both criteria must be met at the same time for the MCS to be deemed a crosser. Otherwise, the squall line will be considered a noncrossing MCS. While these definitions probably do not overlap with those of Keighton et al. (2007), they at least serve to distinguish weaker (and likely nonsevere) convection from stronger (and potentially severe) convection.
To assure consistency with the work of FM06 and set a baseline for the experiments, control simulations were performed both with and without topography. Hovmöller diagrams of selected fields in Fig. 2 illustrate the evolution of the squall line over time, and Fig. 3 shows horizontal plan views of surface simulated reflectivity. The contrasts between the two control runs clearly demonstrate the impact of terrain on a convective system. Upstream (west) of the mountain peak, the base-state wind's interaction with the terrain induces small amounts of rising motion, slightly enhancing ascent at the lowest model level (Fig. 2f). Downstream (east) of the mountain peak, there is an obvious weakening in the convection (Figs. 2d and 3f) due to ambient sinking motion as the system and its cold pool move downslope (Figs. 2e,f). This suppression is followed by a sudden reintensification near the base of the mountain (x = +70 km in Figs. 2d and 3g,h), consistent with the conceptual model of FM06. The strength of the cold pool over time also reflects this weakening and reinvigoration pattern in the presence of terrain (evident in Fig. 2e). In the immediate lee, the cold pool is warmer when topography is present as a result of partial blocking and downslope warming; however, when convection reintensifies near the base of the mountain in the lee, the cold pool still acquires a strength comparable to that simulated with no topography (Figs. 2b,e).
As in FM06, this sudden reintensification of the convection in the lee is attributed to a hydraulic jump of the cold pool. To illustrate the evolution of the cold pool as it traverses the barrier, along-line averaged cross sections were computed relative to the objectively determined surface gust front location at every y point. This provided a clearer picture of the leading edge of the cold pool while correcting along-line phasing differences due to bowing (e.g., Figs. 3e,f). These cross sections illustrate the FM06 mechanism at work: vertical velocities become weaker and shallower as the cold pool traverses the mountain (Figs. 4a–c) and subsequently reintensify and deepen as the outflow pools in a hydraulic jump at the base of the mountain (Figs. 4d,e). While the outflow does not thin during descent as dramatically as in FM06, surface wind speeds near the head of the cold pool strengthen during this period and weaken after the outflow deepens, consistent with a transition from supercritical to subcritical flow (not shown). The less drastic thinning of the cold pool than in FM06 is mainly tied to the use of a broader barrier width, which results in more gradual system variations.
In addition to this fundamental FM06 sequence, further deepening and cooling of the outflow occurs farther downstream after the cold pool's hydraulic jump occurs (Fig. 4f). This further strengthening of the outflow is tied to the incorporation of new cells that develop approximately 5–10 km ahead of the outflow after it reaches the base of the mountain (Fig. 3g). While the development of these new cells is at least partly related to lifting along the outflow boundary, a dry simulation shows that the environmental flow over the barrier is associated with midlevel vertical motion near the location of these new cells (Fig. 5a). Broad, upwind-tilted orographic gravity waves are the initial response of the flow to the imposed terrain (Fig. 5b). However, as the prevailing flow continues to traverse the barrier and descend in the lee, an environmental hydraulic jump develops (Fig. 5c). Such a feature has been recognized to generate convective cells in the lee of terrain in previous studies of orographically generated convection (e.g., Chu and Lin 2000; Chen and Lin 2005; Miglietta and Rotunno 2009). Immediately downstream of the environmental hydraulic jump there exists a train of high-amplitude, short-wavelength gravity waves. Such a wave train has also been demonstrated in previous studies (e.g., Fig. 3c of Durran 1986). In the control run, the environmental hydraulic jump is visible as a thin line of upward velocities (see arrow at x = +50 km in Fig. 2f). Once the zone of lifting associated with the system's outflow reaches this pocket of ascent, several additional convective cells develop and quickly merge with the parent MCS.
The experiments performed by FM06 used rain-only microphysics, whereas the present simulations include ice. To determine whether the current simulations with ice fall into the same parameter space as FM06, an additional control simulation with an identical model configuration but with rain-only microphysics was performed (Kessler 1969). A comparison of the two control simulations in Fig. 6 illustrates a similar overall evolution; however, it is clear that the inclusion of ice microphysics allowed for a larger stratiform region (Figs. 6a,b) and lower θe in the surface outflow (Figs. 6c,d). The rear inflow is correspondingly stronger with ice, and it descends more substantially. Consequently, the amount of midlevel θe air brought down to the surface is also enhanced (Figs. 6e,f). Despite these differences, the upstream Froude numbers (i.e., the degree of blocking) within in the two cool pools were similar (not shown). The control simulation with ice microphysics contained a cooler and drier cold pool with higher stability, yet the descending rear inflow compensated for this by adding kinetic energy to the cold pool, producing a comparable outflow Froude number to the rain-only simulation. Thus, the current simulations with ice are expected to fall in the same part of the parameter space as those of FM06. The inclusion of ice microphysics, however, leads to more realistic system structures in the present study.
In summary, the control simulation largely upheld the FM06 conceptual model of enhancement, suppression, and reinvigoration. During lee reinvigoration, lifting following the hydraulic jump of the cold pool was locally supplemented by ascent s a result of a hydraulic jump of the large-scale flow. The tandem acted to initiate additional preline cells in the lee. Once the original system merged with this new convection, its updrafts became significantly stronger and its cold pool depth and temperature approached those in the no-terrain control run. As a result, this simulation is considered a crossing MCS and it serves as a baseline for the rest of the experiments.
It was evident in the control simulation that slope flows can have both a beneficial and detrimental impact on organized convection encountering terrain. Since the observed crossing cases in LP10 were associated with a weaker mean wind than the noncrossing cases, the first set of sensitivity experiments tested the hypothesis that a stronger mean wind is less favorable for a crossing MCS due to stronger lee downslope flow, while a weaker mean wind is more favorable for a crossing MCS due to weaker lee downslope flow.
When the wind speed at every level of the wind profile was increased by 5 m s−1 (Fig. 1b), the overall evolution of the convective system still adhered to the pattern of orographic enhancement, suppression, and restrengthening (Fig. 2g). The stronger base-state wind speed–induced enhanced slope flows, resulting in more orographic enhancement and colder outflow on the upstream side of the barrier (Fig. 2h). The higher mean wind also produced stronger lee sinking motion (Fig. 2i), which acted to suppress the convection for a greater distance downstream from the mountain (i.e., strong convective redevelopment at x = +100 km downstream in Fig. 2g vs x = +70 km downstream in Fig. 2d) and weaken the updrafts in the lee (Fig. 7). However, the updrafts remained vigorous enough (and the simulated reflectivity remained high enough) that this system meets the definition of a crossing MCS (section 2c).
In summary, a stronger mean wind did not prevent the MCS from successfully traversing the terrain, despite enhanced lee suppression of the system. Given the greater lee suppression, it is worth considering whether further increases to the mean wind would lead to dissipation of the MCS. An additional simulation that increased the mean wind by 10 m s−1 produced widespread pre-MCS convection over the terrain (due to intense low-level upslope flow), making it impossible to assess the actual MCS–terrain interaction. Based upon repeated experimentation, it appears that the primary effect of increasing the mean wind is simply to intensify the pattern of enhancement and suppression due to the stronger slope flows. At least in the favorable Weisman and Klemp (1982) thermodynamic sounding (with large CAPE and minimal CIN), the enhanced cross-barrier flow is not sufficient to suppress convective redevelopment in the lee of the terrain.
Decreasing the mean wind by 5 m s−1 (without changing the bulk shear) provided a different environment than the previous experiments due to a low-level flow reversal (easterly wind at the surface changing to westerly aloft; see Fig. 1b). This led to the development of a new convective system well ahead of the original squall line that was traversing the mountain; this new convection eventually replaced the original system (Fig. 2j). Other studies have found similar results in low wind speed experiments (e.g., Chu and Lin 2000; Chen and Lin 2005; Reeves and Lin 2007; Miglietta and Rotunno 2009). Anecdotally, the authors have observed similar behavior on a number of days near the Appalachian Mountains, so it is worthwhile to understand the origins of the new system. Two additional simulations were run to determine the source of the new MCS: one without moisture and one with moisture but without the initial line thermal used to generate the primary squall line. Examination of the dry simulation did not reveal any environmental mountain waves that could have contributed to the new convection on the east side of the barrier. However, the model run with moisture but without the primary (western) squall line still produced a new system to the east of the barrier in a similar location to the one in the original "mean wind −5 m s−1" simulation (not shown). Inspection of this simulation revealed that the convective system was a simple result of moist upslope flow impinging on the topography. Clouds were generated by the gradual ascent, and convection eventually developed as small-scale perturbations within the model lifted some parcels to their levels of free convection.
While the orographically generated squall line makes it difficult to interpret the evolution of the original MCS, it appears that the first MCS experienced a similar pattern of orographic interruption and enhancement as the other simulations (cf. Figs. 2d,g,j). West of the barrier, convection was suppressed before it reached the barrier peak, in large part due to the presence of ambient sinking motion resulting from the low-level easterly flow encountering the barrier (Fig. 2l). Despite this suppression, convective reinvigoration still occurred, notably closer to the peak (x = +30 km in Fig. 2j) as a result of the ambient rising motion to the east of the barrier. Due to its weakening west of the peak, the original MCS exhibited a warmer cold pool (Fig. 2k). The cold pool still remained strong enough to produce some lee reinvigoration and surface-based convection despite the presence of the second MCS. It should be noted that this simulation may not be directly comparable to the other experiments, as the formation of the second MCS likely altered the downstream environment. Furthermore, the second MCS that develops also makes it difficult to parse out the purported benefit of a weaker environmental mean wind; however, the original system was indeed able to overcome environmental subsidence west of the mountain peak, and was suppressed for a shorter distance and duration before being enhanced by ascent to the east of the barrier.
In addition to a weaker mean wind, LP10 found that crossing MCSs were associated with weaker vertical wind shear. Taking RKW theory into consideration, it was hypothesized that because the cold pool weakens and becomes partially blocked as it crosses the barrier, less environmental shear is required to balance the cold pool in order to create a vigorous, upright gust front updraft. Several simulations that varied the low-level shear tested this hypothesis.
The first test increased the bulk shear in the lowest 2.5 km by 5 m s−1 (Fig. 1c). As determined by the averaged reflectivity (Fig. 8a) and the averaged maximum vertical velocity (not shown), this increase in shear did not prevent a crossing MCS. A few differences between this simulation and the control were clear. First, the increased shear resulted in a warmer cold pool upstream (cf. Figs. 2e and 8b), which seemed to occur because the stronger shear initially produced an overturning updraft and a small amount of leading stratiform precipitation (e.g., as in Parker and Johnson 2004). Such a configuration entails less evaporation of precipitation into the trailing cold pool. The second difference was that the system restrengthened slightly farther downstream of the mountain (x = +100 km in Fig. 8a). Finally, the squall line contained more bowing segments as a result of the greater shear (not shown), which is consistent with the sensitivities reported by Weisman (1993). Despite these low-level differences, the terrain-induced evolution was similar to the other simulations; increasing the shear was not particularly detrimental to the maintenance of the squall line.
To fully assess the applicability of RKW theory to the parameter space, it was desirable to determine whether the increase in shear resulted in a greater or lesser imbalance between the theoretical density current speed C and the bulk shear ΔU. The current speed C was calculated at several locations upstream and downstream of the barrier in the same manner as Weisman and Rotunno (2004) and Bryan et al. (2006) in order to illustrate the evolution of the balance between the cold pool and shear. The equation for calculating C is
where H is the cold pool depth, and B is the buoyancy,
θ is potential temperature, overbars indicate the base-state values, and qυ, qc, and qr are the mixing ratios of water vapor, cloud water, and rainwater, respectively. The base-state bulk shear is used for ΔU. According to RKW theory, C/ΔU = 1 is ideal for gust front lifting.
A comparison of the simulations in Fig. 9 demonstrates the influence of terrain on C, and consequently on C/ΔU. Without terrain, C and C/ΔU change very little over time in the control simulation and C/ΔU remains >1 (gray line with circles in Fig. 9). However, in the presence of terrain, C and C/ΔU are modified as the convective system encounters the barrier (black line with squares in Fig. 9). As discussed previously, the cold pool undergoes orographic enhancement, suppression, and reintensification, and these changes are directly reflected by C. In terms of RKW theory, in the control run with terrain, C/ΔU was still almost always >1, except at x = +50 km when C decreased in the lee and C/ΔU became ≈1 (Fig. 9b). In other words, according to RKW theory, the cold pool lifting in the control run was nearly optimal during the key stage of lee system redevelopment. Increasing the bulk shear by 5 m s−1 caused C to exhibit slightly larger fluctuations than in the control simulation, with C/ΔU falling a bit below 1 in the immediate lee (gray line with triangles, Fig. 9).
Additional simulations tested further increases to the low-level shear in order to determine whether a noncrossing MCS would result. As the bulk shear in the lowest 2.5 km was increased by 10 and 15 m s−1 (over the control; Fig. 1c), C/ΔU correspondingly decreased downstream in the zone where system reformation occurs (x = 0 to x = +100 km; black line with circles and gray line with squares in Fig. 9b). However, despite the greater imbalance between the cold pool and shear, system redevelopment still occurred (Figs. 8d,g), with corresponding subsequent rebounds in C (Fig. 9a). Thus, within the present experiments' parameter space, even if the shear is quite strong relative to the cold pool, it does not prevent system redevelopment and MCS maintenance across terrain.
A final sensitivity test decreased the bulk shear by 5 m s−1 in the lowest 2.5 km (Fig. 1c). Although C/ΔU was always >1 (black line with triangles in Fig. 9), the simulation nevertheless produced a crosser (Fig. 8j). This illustrates that a squall line can traverse the barrier in a lower-shear environment that is similar to what LP10 observed (although LP10 did not have a measure of C). The weaker shear caused the midlevel updraft to be displaced 10–20 km behind the gust front updraft throughout the simulation (e.g., midlevel updraft near x = −15 km and gust front updraft near x = 0 km in Fig. 10a). Even so, the lee reinvigoration process was sufficient to overcome the minimal CIN, renewing convection in the lee and producing a crossing MCS much like the control simulation.
To recap, within a favorable thermodynamic environment, the cold pool–shear relationship does not appear to be a deciding factor for whether or not a simulated MCS will be a crosser. In the observations of LP10, shear and mean wind were highly correlated. Based upon the experiments described above, it appears that the mean wind has a greater dynamical impact upon the terrain-induced enhancement and suppression, while the shear has a secondary effect on the structure and intensity of the resulting convection. To fully isolate the effects of low-level shear from those of the mean wind, two additional sensitivity tests were performed that kept the mean wind constant in the lowest 2.5 km while either increasing or decreasing the bulk shear by 5 m s−1 (Fig. 1d). Under this configuration, the period of suppression in the immediate lee (x = 0 to x = +75 km) was much more pronounced in the case with weaker shear (Figs. 11a,b). The reason for this more notable suppression appears to be tied to the enhancement of the system's cold pool upstream of the barrier, with increased stability of the cold pool entailing greater blocking by the terrain.
In the simulations presented herein, the mean wind contributes to the overall enhancement and suppression of the convection due to large-scale rising and sinking motion. Meanwhile, the shear influences the temperature and depth of the cold pool, and to some degree the ratio of C/ΔU in the lee. Despite these impacts, none of variations in the wind profile tested herein alone resulted in a noncrossing MCS. On the one hand, these experiments might overstate the role of the wind profile because it was modified over the entire domain (whereas the differences in LP10 were only significant in the lee). On the other hand, these simulations might understate the role of the wind profile because they used a very favorable thermodynamic environment.
The previous simulations clearly demonstrated that in a low CIN, high CAPE environment, modifications to the wind profile alone do not produce a noncrossing system, but do exert some influence on the evolution of an MCS traversing terrain. What is the influence of the wind profile in a lower instability, higher inhibition environment, such as what LP10 observed in their noncrossing cases? To answer this question, additional simulations were run in which the low levels were cooled or dried in the lee to achieve lower CAPE and higher CIN.
The first test cooled the surface in the lee of the terrain by 6 K, with maximum cooling achieved by the time the squall line reached the barrier peak, resulting in a surface-based CAPE (SBCAPE) of approximately 825 (2290) J kg−1 and a surface-based CIN (SBCIN) of −150 (0) J kg−1 in the lee (Fig. 12a). These were substantially lower SBCAPE and SBCIN values than in the control run (1790 and −20 J kg−1, respectively) whereas the MUCAPE and MUCIN values (based on a parcel located 1200 m above the surface) were unchanged. This cooling setup, while idealized, mimics the phenomenon of warm season cold air damming in the lee of the Appalachians (Bell and Bosart 1988). Despite the marked decrease in SBCAPE and increase in SBCIN, the MCS successfully crossed the terrain (Fig. 13a). While their severe weather potential is more limited, crossing cases have occurred when cold air damming is in place (Keighton et al. 2007). In the present simulations, the recurrence of strong lifting in the lee (Fig. 13e), in addition to available instability within and above the stable layer, maintained the squall line despite the enhanced surface-based inhibition.
Since cooling the lee by 6 K still resulted in a small amount of SBCAPE, an additional test was performed that cooled the lee by 12 K. The resultant SBCAPE (MUCAPE) was 0 (1370) J kg−1 and SBCIN (MUCIN) was 0 (−5) J kg−1 (Fig. 12a). While the instability for both surface-based and elevated parcels was greatly reduced compared to the control, a crossing MCS (albeit somewhat less intense) was still produced (Fig. 13b). A key difference, however, was the development of a propagating internal bore on top of the stable layer as the system became elevated (leading edge near x = +220 km in Fig. 13f). This bore became the primary lifting mechanism that helped maintain the convection downstream of the terrain. This transition from a surface-based to elevated squall line appears to follow the same processes as described by Parker (2008).
Interestingly, the simulations with cooling actually had a narrower downstream zone of suppressed convection in the immediate lee of the barrier (x = 0 to x = +70 km; cf. Figs. 13a,b and 2d). In the control simulation, the system is cold pool driven, and lifting is suppressed until the cold pool's hydraulic jump occurs. In contrast, cold pool-relative cross sections in Fig. 14 demonstrate that in the presence of cooling, the system becomes bore driven before the hydraulic jump in the cold pool occurs. As a result, strong updrafts are reestablished sooner (i.e., not as far downstream; Figs. 14a,b). As the amount of cooling increases, this transition to bore-driven lifting occurs more quickly. The vertical velocities weaken as the system moves farther downstream as a result of the lowered CAPE and more gradual slope in the isentropes (Fig. 14c). Thus, the shorter window of suppression does not equate to a stronger overall system.
The main implication of these cooling simulations is that MCS maintenance is strongly linked to the presence of sufficient downstream instability. Even in a lee environment with no surface-based instability, a crossing MCS was produced because elevated parcels in the lee with minimal inhibition were lifted to their levels of free convection. While this result is fairly unsurprising given the findings of LP10, additional cooling simulations with increases to the mean wind produced nearly identical results (not shown). This suggests that the cooling approach fell short of identifying a combination of nonzero MUCAPE and larger MUCIN that could critically test whether the wind profile plays an important role in a sufficiently unfavorable environment. Additional tests were employed that decreased MUCAPE and increased MUCIN via drying, as discussed next.
Noncrossing cases have also been observed to move into drier environments (LP10), thus idealized changes to the moisture profile downstream were employed to weaken the instability and increase inhibition. Only the lowest 2–3 km were modified because the observed differences between case types in LP10 were concentrated in the low levels. As in the cooling simulations, drying was complete by the time the squall line reached the mountain peak. Decreasing the boundary layer mixing ratio in the lee to 11 g kg−1 (Fig. 12b) did not reduce the MUCAPE and increase the MUCIN enough to prevent system redevelopment in the lee or result in a noncrossing MCS, even when the mean wind was increased (not shown). Utilizing the average observed moisture profile for all soundings in LP10 over the lowest 3 km (Fig. 12b) resulted in SBCAPE and MUCAPE values of 600 J kg−1 and SBCIN and MUCIN of −20 J kg−1. This downstream environment produced a convective system that underwent a period of weak reintensification (from x = +50 to x = +100 km in Figs. 15a,c). This system is still classified as a crosser because of the lee updrafts of at least 5 m s−1 associated with simulated reflectivity of at least 40 dBZ. Increasing the mean wind in this environment, however, further hindered the system's lee redevelopment (Figs. 15b,d), such that it became a noncrossing MCS according to the definition in this study. In other words, changes to the wind profile did play some role in determining MCS maintenance when the thermodynamic environment was sufficiently inhospitable for convection.
An interesting question is whether or not this environment would support maintenance of a squall line over flat terrain. That is, would this environment lead to MCS dissipation regardless of the terrain? Additional simulations were run in which the "lee" was dried to the average observed moisture profile in LP10, but without terrain. When the terrain was removed, simulated reflectivities and vertical velocities remained above the crossing threshold well into the lee drying zone (Figs. 16a,e). Without terrain, the cold pool was not interrupted (Fig. 16c), nor was the system subject to downslope suppression. Instead, a more gradual weakening of the system occurred (Fig. 16a). Thus, it is clear that the impact of both terrain (with a stronger mean wind) and the less favorable lee thermodynamic environment both played a role in producing the simulated noncrossing MCS. Numerous other treatments of the downstream thermodynamic environment (not reported here) confirm MUCAPE as the most important parameter for simulated MCS maintenance over terrain, particularly when combined with MUCIN. The influence of the wind profile is generally smaller, but is not negligible when instability is small and inhibition is large.
Through the use of idealized sensitivity tests, the first-order impacts of the wind profile upon MCSs traversing terrain have been examined. While LP10 showed that weaker shear and a weaker mean wind were associated with crossing MCSs, the present work finds that the wind profile alone does not play a primary role in determining idealized squall-line maintenance over a barrier similar to the Appalachians. However, the wind profile does influence the evolution of the MCS. Variations in the mean wind impacted the degree to which the system was orographically enhanced upstream and suppressed downstream, while changes in low-level shear were shown to modify the strength of the outflow, and to influence the conditions for gust front lifting in the lee. Despite these effects, a lee hydraulic jump in the outflow renewed lifting at the head of the cold pool (much like FM06 described) in each wind profile experiment. Tests that decreased the downstream instability through low-level cooling or drying still produced crossing MCSs with the control wind profile. A combination of substantial lee drying and increased mean wind did finally result in a terrain-induced noncrosser (as defined in this study).
In the datasets of Keighton et al. (2007) and LP10, most of the observed noncrossing MCSs failed to survive even as weak (nonsevere) convection in the lee. Likewise, Parker and Ahijevych (2007) estimated that only 10%–30% of convective systems survive crossing the Blue Ridge Mountains. The robustness of the squall lines in the present study is probably due to the extremely favorable initial sounding that was used (i.e., that of Weisman and Klemp 1982). The use of this sounding helps connect the present results to those of FM06, and it was found that the idealized model utilized herein had difficulty producing convection at all with the drier, more stable mean soundings from the LP10 study. Additional experiments (not shown) incorporating the LP10 observed soundings only into the lee of the idealized simulations were also unsatisfactory. Future studies with more inhospitable soundings would be useful, although a less idealized modeling framework (e.g., case study simulations) appears to be needed. A few other potentially important factors were also excluded. For example, the diurnal cycle was not included in the simulations, which affects the development of orographic slope flows and low-level jets. Furthermore, the present idealized study did not include cross-barrier changes in bulk shear and mean wind, which LP10 found to discriminate between crossing and noncrossing squall lines. This study also did not address situations in which the cold pool is completely blocked by the terrain, although in lower mountain chains such as the Appalachians, complete blocking of a 1–2-km-deep cold pool is unlikely. Finally, it has been shown by LP10 that both crossing and noncrossing cases tend to be associated with varying kinds of synoptic-scale fronts, thus it may be useful to explore the influence of larger-scale processes on squall-line longevity. Such avenues would provide additional understanding and help extend these idealized results toward tangible improvements in operational forecasting of these systems.
The authors thank members of the Convective Storms Group at North Carolina State University for their assistance and feedback throughout the course of this study. Comments from two anonymous reviewers provided valuable suggestions that improved the quality of this manuscript. This research was supported by the National Science Foundation under Grant ATM-0552154 and by National Ocean and Atmospheric Administration's Collaborative Science, Technology and Applied Research (CSTAR) Program Award NA07NWS4680002.
Strictly speaking, the "supercritical" or "subcritical" terminology refers to wave propagation flow regimes in shallow-water theory. In this paper, these terms will be used to describe stratified flow that strongly resembles the regimes in shallow-water theory.
https://journals.ametsoc.org/view/journals/mwre/139/10/2011mwr3635.1.xml

redpajama_set_name: RedPajamaCommonCrawl


Beis Moshiach presents Section 7 of the maamer the Rebbe MH"M delivered on Yud Shvat 5717, in accordance with the custom established by the Rebbe to review each year a section of the Rebbe Rayatz's maamer Basi L'Gani of 5710. • This year we focus on the seventh section of the profound and foundational Chassidic discourse.
A few minutes before his passing, the Rebbe Rayatz lifted himself a bit from the bed and screamed these words. He then lay back down, and a scant few minutes later his holy soul soared heavenward. * In honor of Yud & Yud-Aleph Shvat, the day of the passing of the Rebbe Rayatz and the day the Rebbe formally accepted the Nesius, the Rebbe's secretary, Reb Yehuda Leib Groner, shared with Beis Moshiach his memories of yechidus experiences, the t'fillos, the farbrengens, the work of preparing the maamarim for print, the Rebbe's daily yechidus with the Rebbe Rayatz, and the belief in the Rebbe Rayatz as Moshiach. Until the hearing of the bitter news, that long Shabbos in the shadow of painful grief, the drama that unfolded at the burial and the powerful statement that the Rebbe said to him the day after the funeral.
This Shabbos (Bo) is the Shabbos before Yud Shvat. All Chassidim are preparing themselves to be "Mekabel the Nesius and Malchus" of the Rebbe. In this article we will "farbreng" based on the HaYom Yom that the Rebbe personally chose for Yud Shvat.
Our elders often caution us not to walk around the house without shoes. Is this just a bubbe meiseh (grandmothers' tale), or does it have a source in halacha?
The Rebbe turned to him and said, "I love every Jew with a tremendous love and I hope that due to my love for them, they reciprocate that love in kind." * It is incumbent on a Chassid to connect and cleave to the Rebbe, the true source of true life, and to be constantly preoccupied with this love, the love of his life.
Thousands of Chassidim packed into the Rebbe's beis midrash and listened closely to what the Rebbe had to say. It was seemingly a routine farbrengen on Shabbos Mevarchim. The Rebbe began with timely remarks about the special quality of Shabbos Mevarchim Nissan which is the "head" of the months. Between sichos, the Chassidim lifted their cups and the Rebbe responded to the l'chaims of each of them.
DINUSH IS HOME AND EATING!
Dinush, who garnered worldwide attention with the campaign to raise funds for her operation, has returned home. * Exclusive: Her mother, Chaya Rivkin, shares the hard times, the miracles, and the gratitude.


Conversations with Creators is a collaborative interview series designed to understand the processes and inner workings of the artist, their creations, and how their work impacts the comic booking industry. Each meeting is candid and personal, seeking to explore previously unexplored avenues of insight.
Royden Lepp is the creator of Rust, an acclaimed diesel punk published by Archaia Entertainment. He is currently working on the 4th volume of Rust. The first three are out and available to purchase via amazon.
Stuart Warren: So thank you for meeting with me Royden.
Royden Lepp: It's a pleasure Stuart.
Stuart Warren: What brought you to comics?
Stuart Warren: And when was this? As in what year?
Royden Lepp: Hmmm… Mid to late 80′s?
Stuart Warren: What was your first impression reading a superhero comic?
Royden Lepp: It just seemed like such a perfect method of storytelling, compact, concise, and engaging. Spiderman wasn't new to me but I think sequential storytelling was. I'd read Calvin and Hobbes and other "strips," but nothing that had any in-depth, ongoing drama.
Stuart Warren: There was this fad, and I'm not sure how aware of it you were when you first started, that comics in the 80s were rather dark. Did this come across to you in any way?
Royden Lepp: Spiderman stayed pretty light as I read it. I don't think I ventured into the dark stuff; maybe a bit more in the 90′s in some of the Image stuff. But I had to hide Terminator and Alien issues from my parents! I guess that was Vertigo, or Dark Horse? I can't remember.
Stuart Warren: Comics, I've been told, is somewhat of a juvenile term. Now that "Graphic Novels" have become more commonplace in the market, more publishers are creating extended stories that unfold more like traditional books. Did this appeal to you when you decided to start working with Archaia? And did you feel that Archaia could allow you to tell your Rust story more effectively?
Royden Lepp: It did. I liked the "book" format. I liked the idea of never releasing single issues. That's not how I like to tell stories anyway, I need more than 27 pages. Archaia allowed me to tell Rust the way I wanted to and even tried to make it feel more "novely" than any graphic novel I've ever picked up. That's my favorite thing about Rust, it's a book I'd buy without thinking twice if I came upon it somewhere on a shelf. Archaia has a lot to do with that.
Stuart Warren: For those who don't know, Rust is one of your more notable works, a Noir Thriller set in the American Mid-West with Diesel-Punk elements. What influenced you to write the story?
Royden Lepp: Definitely my childhood, growing up in the Canadian prairies. My Dad was a farmer. My memories of the farm are distant and hazy. I could swear there were robots.
Royden Lepp: I basically took that setting, that quiet solitude of the prairies, and added the genre element. I love science fiction, I love robot stories, but I like it when they're grounded in something tangible and believable. That's how Rust came about.
Stuart Warren: One thing that I've always liked about the characters in Rust is that they are very similar to the people that we encounter in our own lives.
Stuart Warren: One of your characters is blind and I can relate to this. My grandmother is blind.
Royden Lepp: Mmm, I did not know this. You and I have talked often and you never mentioned it.
Stuart Warren: Yeah. Being blind is interesting. We don't often reflect on what it would be like to be completely without a sense, as in the five senses. Especially considering that this is a graphic narrative, one that requires sight to be fully engrossed in the story, I found it interesting that a main character is unable to appreciate sight the way most people do. Did you base this character off of anyone in particular?
Royden Lepp: Yeah that's true. I did spend a lot of time thinking about Ava (the blind girl) and how she would "see" the world and the threats that show up. She's not based off of anyone really, just a character I really saw in my mind and really fit into the story the way I wanted. But speaking of disabilities, Oz, one of the main characters, 8 or 9 year old boy, is missing his right hand, he has a hook.
Stuart Warren: Yeah, and I only recently caught that.
Stuart Warren: Does your dad resonate with the character, or appreciate how you included him in the story?
Royden Lepp: I don't know. He never got to read it. I was working on Volume 1 when he passed away.
Stuart Warren: I'm sorry to hear that. I had no idea.
Royden Lepp: He got to see some of the work but never got to read it as a whole. I used to accidentally draw Oz with both hands all the time and I'd complain to him that I had to keep going back and correct the art. He thought that was really funny for some reason.
Stuart Warren: Did you and your father's relationship influence the work in any way? Rust is a generational story, I feel, one that follows a son, with the wisdom of the grandfather interspersed. Was this family dynamic also present in your life?
Stuart Warren: Now, you say you grew up in Canada. So why did you set the story in the American mid-west? Was that done for the sake of style?
Royden Lepp: Well… Technically I didn't! I wanted the setting to look familiar but I'm not ever really stating anywhere that it's America, or even earth for that matter. I'd rather depict an alternate earth rather than an alternate history. For all you know it could actually be Canada!
Stuart Warren: Ah, how strange. I never considered that.
Royden Lepp: But the great long war that's referred to in the prologues is not the first or second world war. It's something else, from another time and place. Mid-west Canada looks strikingly similar to mid-west America, actually.
Stuart Warren: I admit that I have still yet to read volume 2 and 3. 3 Recently came out I believe.
Royden Lepp: In May, yeah.
Stuart Warren: What's the reception been so far?
Royden Lepp: Volume 3 is my personal favorite of the series so far. I think fans are agreeing. It's the biggest cliffhanger in the book (greatest cliffhanger in the series I should say), so people aren't as happy about that. But overall it's been warmly received. Great reviews.
Stuart Warren: When you set out to create Rust, did you have a particular end in mind? How many volumes do you envision?
Royden Lepp: I've always know Rust would be 4 volumes. I knew how it would end, but I wasn't always sure how I would get there. There were some twists and turns in the plot and my editor, Tay, really helped me nail down my plan. She was pivotal in the process for me. She helps me assemble my thoughts.
Stuart Warren: I thought about the production model for most comics and graphic novels as being artist/writer teams. What is it like being able to create something that you author and draw simultaneously?
Royden Lepp: love telling stories. I love drawing. I can't imagine doing this any other way.
Stuart Warren: Other than Tay, is there any other editorial oversight on behalf of your publishers?
Royden Lepp: Not really. Many others get to read Rust before it goes to print, but feedback is all filtered through my editor.
Stuart Warren: That must give you a lot of freedom to shape your story.
Royden Lepp: Great freedom. Yes.
Stuart Warren:Do your personal beliefs and philosophy have sway over the stories you write?
Stuart Warren: What do you think the worldview of Rust contends with? Obviously there are some that might reject it.
Royden Lepp: Of course. And actually they can reject it and still enjoy it. Rust is about decay. It's about loss: of family, of relationships, of trust, of purpose, and of hope. And it's about renewal. It's about responsibility, change. Should I keep going?
Stuart Warren: Well, you bring up some interesting themes.
Royden Lepp: It's a lot about true freedom.
Stuart Warren: What is your objective in Rust, as in, what kind of proposition are you making to your reader? Are you asking them to reassess what they live for, or how they see the world? Or are you trying to create a world in which the reader encounters a simpler life that is bolstered by essentials? And I suppose, considering true freedom, what is that to the reader?
Royden Lepp: Well… I don't want to give too much "instruction." I want people to interpret the themes as they see fit. But the one question I ask is "what is true freedom?" Or moreover, what kind of freedom brings the most satisfaction in life? Is it the freedom to be and do anything? I think freedom is more simple than that, but that's the question I'm posing. Yeah, it's hard to get into.
Stuart Warren: Well I know that your personal faith likely influences the themes. But that just shapes the world you know.
Royden Lepp: Of course. I have my beliefs about life, about all life, and I'd be lying if I said those things weren't underlying in the themes of Rust. I can't avoid them. I can't ignore them.
Royden Lepp: Interesting observation. I've never noted that.
Royden Lepp: It's true. Comic is one of the easiest ways to tell a story. I've heard many say that comics are the new screenplay, only with concept art. Comics are a great freedom.
Stuart Warren: So as you finish up Rust are you in the process of launching another project? Or would you plan on working with a writer from Archaia to create another story in the mean time?
Royden Lepp: Unfortunately, I still have a lot of work left on Vol4. I've had a tumultuous year with the birth of my first son. So I'm still 100% focused on Rust. I have some really strong ideas for what my next book will be, but by the time I start drawing it… and by the time you get to read it… We might as well not talk about it yet. But I will write and illustrate again.I enjoy it too much. There are a number of writers I'd love to work with. But I just need to tell my own stories as long as people still want to read them.
Stuart Warren: If you could work with one famous comics writer who would it be?
Royden Lepp: Ha! Hmm. On the spot. I'm not sure they'd be famous. I have friends I'd like to work with, people with whom I share vision. I don't know that I could name anyone off the top of my head.
Stuart Warren: Too many good ideas?
Royden Lepp: I hope they're good!
Stuart Warren: Well our time is almost up. In the tradition of Conversations with Creators, I wanted to ask you, when you get the pearly gates, what are the first words you want to hear god tell you?
Stuart Warren: Beautiful. Thank you for your time, Royden. It has been a pleasure getting to know you and your work.
Royden Lepp: I always enjoy our conversations, Stuart. Please come see me at a con again sometime soon.
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Today is a big day!! Summerfest '13 is open, and it is full of summery awesome!
Second Spaces is happy to be a part of Summerfest, and I've got two new items available!
First is the Poolside Beverage Cart - a vintage piece, stock full of refreshing drinks and adorable picnic items - you need this for your next pool party!
Then we have the City Pool Storage Lockers - salvaged from the now-defunct public pool in Ahern, these lockers are great for storage anywhere, inside or out! The full set is available, including the shelving and all the lockers you could want - or you can buy the lockers-only set, which comes with three configurations of lockers to suit all your storage needs.


Open Dining Room Contemporary Twenty One Two , Download this wallpaper for free in high resolution. Open Dining Room Contemporary Twenty One Two was posted in May 22, 2018 at 1:58 am and This Open Dining Room Contemporary Twenty One Two Wallpaper has viewed by 78 users. If you wanna have it as yours, please click full size and you will go to page download in full size, so you just choose the size above the wallpaper that you want in "Download", Click it and download the Open Dining Room Contemporary Twenty One Two Wallpaper.
Home Design , Best Open Floor Plan Home Designs was posted February 24, 2016 at 11:27 am by Home Design Ideas .
Dining Room , Open Dining Room was posted March 26, 2016 at 6:15 am by Home Design Ideas .
Home Design , Open Patio Ideas was posted December 31, 2018 at 3:10 am by Home Design Ideas .


You may have noticed that I never use matte top coats in my nail art. This is not because I have anything against the matte look; in fact, I love it! It's just that the only matte top coat I had left streaks in the finish, exposing the glossy polish underneath. So when I was choosing something to review from Born Pretty Store, I decided to give their matte top coat a try.
Overall, I was pleased. First I tried it out over Jordana's "Purple Glam". The streaks were minimal and I realised afterwards when looking at the product info page that they probably only existed because I didn't wait until the first layer was completely dry.
Wish my nails were longer though! WHY DID I CUT THEM! Anyway, I wanted to do something a little more special so I got my striping tape out and created this.
I really liked it, although it was a bit tatty in places. I kept wanting to use a top coat to smooth it out but knew that it would ruin the whole effect!
Best thing about this? It's only $3.39! It's on special at the moment so if you want some, don't wait around. You can use my discount code for a further 10% off, too! You can buy it here. They also have heaps of other nail art products too!
I found that matte top coat can settle & then the finish comes out uneven. I added shaker beads to my matte bottles & now they work properly after a good shake.
A friend of mine has this problem too but I don't use Matte enough to notice! I'll let her know though, thanks!


text:
Publication - Strategy/plan
Marine litter strategy for Scotland
Marine Scotland Directorate
Marine and fisheries
A strategy to develop measures to minimise the amount of litter entering the marine and coastal environment.
Annex A Scottish Marine Litter Strategy Strategic Environmental Assessment Post Adoption SEA Statement
2. Overview of the strategy
3. Strategic Directions and actions
4. Delivery mechanism
Annex B Scottish Marine Litter Strategy Final Business and Regulatory Impact Assessment
1.1.1 The Environmental Assessment (Scotland) 2005 Act (hereafter referred to as the 2005 Act) requires public bodies in Scotland to carry out a Strategic Environmental Assessment ( SEA) on their plans, programmes and strategies. SEA examines plans, programmes or strategies as they are developed, to identify any significant effects they may have on the environment. It ensures that environmental considerations are taken into account and, where required, proposes mitigation measures to avoid or minimise any potentially significant adverse effects on the environment. Where possible, opportunities to enhance environmental performance are identified.
1.1.2 Marine Scotland undertook a public consultation on a draft Scottish marine litter strategy from July to September 2013. The SEA Environmental Report that documented the potential significant effects of the marine litter strategy was made available for consultation alongside the draft programme of improvements. This SEA was taken forward by the Scottish Government's Environmental Assessment Team on behalf of Marine Scotland.
1.1.3 As required under the 2005 Act, this post adoption statement forms the final output from the SEA process. It outlines how the findings of the SEA and the views of consultees have been taken into account in the development of the marine litter strategy.
1.2 Structure of this Statement
1.2.1 Section 18(3) of the 2005 Act sets out the information that should be included in this post adoption SEA Statement. In summary, it should include:
How the environmental considerations raised in the SEA have been integrated into the plan, programme or strategy;
How the Environmental Report has been taken into account;
How the opinions of consultees have been taken into account;
The reasons for choosing the plan, programme or strategy as adopted, in light of the other reasonable alternatives considered; and
Measures to be taken to monitor the significant environmental effects of the implementation of the plan, programme or strategy.
1.3 Scottish Marine Litter Strategy
1.3.1 During Parliament's consideration of the Marine (Scotland) Act a commitment was given to develop a marine litter strategy. A strategy provides an opportunity to build on current initiatives, and make the overall effort a more coherent package, and meet international commitments under the Marine Strategy Framework Directive ( MSFD) which requires Member States to achieve Good Environmental Status in their marine waters by 2020.
1.3.2 On 3 July 2013, Marine Scotland launched a public consultation on proposals for inclusion within a draft Scottish marine litter strategy. The proposals presented in the draft strategy covered three main areas:
Vision;
Five strategic directions in the areas of education, reducing inputs, seizing opportunities and economic growth, monitoring and engagement; and
Options for delivery of the marine litter policies.
1.3.3 In parallel, a consultation on a national litter strategy was launched on provisions to manage litter in Scotland's terrestrial environment.
2. ENVIRONMENTAL CONSIDERATIONS
2.1 Key findings of the Environmental Report
2.1.1 An Environmental Report was produced presenting the findings of the SEA undertaken on the draft strategy. Overall the SEA found that the marine litter strategy, together with the national litter strategy would be likely to have a positive effect for the environment in the long term in reducing litter and fly- tipped material, and a long term cumulative benefit for Scottish waters (and those of other North Atlantic states). The SEA also found that the efforts of the strategies to reduce and clear existing litter will also have long term benefits in terms of biodiversity, water quality, and improvements in amenity.
2.1.2 The possible effects on population and human health identified as a result of the proposals have been defined as a reduction in the risk of disease related to the incidence of bacterial contamination of water and reductions in litter sinks.
2.1.3 Existing litter in the seas still presents a risk but continuing the Fishing for Litter project will assist in reducing the amount of litter in the marine environment in the long term. This should be considered in more detail as the strategy develops, along with appropriate monitoring to evaluate the effectiveness of such measures.
2.2 Consultation on the draft Scottish Marine Litter Strategy and Environmental report
2.2.1 The SEA Environmental Report on both the draft marine and national litter strategies, together with parallel consultations, were issued for public consultation in July 2013. There were 98 written responses to the consultation on the draft marine litter strategy. The respondents represented a wide range of stakeholders including public bodies, businesses and their industry representatives, environmental non-government organisations and private individuals. These responses have provided a range and depth of views on the draft marine litter strategy which have helped to shape the development of the final strategy. A report presenting an analysis of responses to the consultation on a Draft Scottish Marine Litter Strategy is available at : http://www.scotland.gov.uk/Resource/0044/00446215.pdf
2.2.2 Four responses were received to this statutory consultation on the Environmental Report, which comprised the three SEA Consultation Authorities (Scottish Environment Protection Agency ( SEPA), Scottish Natural Heritage ( SNH) and Historic Scotland) and a public body, Scottish Water. The following section summarises the key issues discussed in these responses.
2.2.3 There was general agreement with the approach taken in the SEA and with the baseline and assessment conclusions. However, SEPA, SNH and Scottish Water provided detail on relevant areas.
2.2.4 SEPA were of the view that monitoring mechanisms outlined in the marine litter strategy should be focussed on implementation rather than the problem itself. SEPA noted that existing monitoring actions should be strengthened to provide the baseline data required for MSFD. SEPA also identified a need for more research and monitoring, with a particular focus on microplastics. Their response also highlighted a need for co-ordination of effort with national and EU partners to develop and standardise methodology for monitoring. Additionally, a request to consider more use of monitoring opportunities in co- ordination with existing activities, such as fishing vessels and ferries.
Scottish Government response:
The strategy outlines action to:
Determine a baseline for coastal litter, seabed and water column, which can be used for Marine Strategy Framework Directive reporting purposes;
Prioritise an initial evaluation on the current state of research;
Undertake research to address key gaps in knowledge, including microplastics in the marine environment;
Develop and standardise methodology in co-ordination with national and EU partners; and
Consider better use of Marine Scotland research vessels to undertake seabed monitoring of marine litter during scientific trawls, and consider additional monitoring opportunities in other marine activities.
2.2.5 SNH commented on the importance of the marine and national litter strategies being aligned, with similar objectives.
This strategy complements the national litter strategy, and while the two strategies have distinct outcomes, both have a focus on the prevention of litter. The alignment of the two strategies is demonstrated through the SEA process and the preparation of a joint SEA Environmental Report addressing both strategies.
2.2.6 Scottish Water highlighted that litter disposal into its systems should be controlled as a source point.
Work with Scottish Water on the scope to reduce Sewage Related Debris.
Address impacts of incorrect disposal of non-biodegradable waste on the water and waste network through education and awareness raising.
2.2.7 The RSPB recommended that the diagram in the SEA (page 4), outlining the policy context for the strategies, should include the Water Framework Directive.
This comment is noted for inclusion in any future iteration of the marine litter strategy and accompanying SEA.
Nikki milne


I am happy to announce that the Shadow Gangs demo is now available in the downloads section here.
It's the PC version, it should run fine on a 1ghz PC with Intel graphics, but let me know if you have any issues running it.
You may need to install Visual C++ 2015 Redistributable here if the Demo won't start, I didn't need to but just in case.
A new music track is also available, here or in the downloads section. It's included in the demo and can be heard if you finish the demo.
The kickstarter date is now set, it's the 25th of June 2016. If you liked the demo and want this game to materialise, please contribute to the crowdfunding.
These kind of games like Shadow Gangs won't be brought back by big game companies, or the likes of Sega, Capcom etc...., they all seem to have moved to 3D and other new fancy gameplay styles etc..., so don't wait for them to release something like Shadow Gangs.
Also feedback on the game all over the internet, here and friends has been very important, and this new demo is showing that. Apart from the new backgrounds, many enhancements and fixes have gone in.


It seems that Khedive Ismail popularized the island when he built his summer palace on there, and a number of royal families followed suite. There are several legend's surrounding Ismail's palace. One is that he built it to house three of his 14 wives, but probably the most popular story is that he built it to accommodate the Empress Eugenie during the inauguration of the Suez Canal. Certainly Eugenie, and other guests of the Suez Inauguration stayed in the palace.. Today, his palace is the Marriott. Other royal residences were also converted for other uses. These include the place of of Price Amr Ibrahim, which is now the Ceramic Museum, the palace of Prince Sa'id Toussoun that is now a branch of the Council of Ministers and the Royal Rest House near the Gezira Sheraton which is now a military establishment.
The island is well known for having a number of fine private schools. The first school we know of that was built on Zamalek was the Catholic Girls College of Bahgat Ali Street and St. Joseph Preparatory School for boys off Gabalaya Street which is today Brazil Street.
The island was also home to Egypt's first modern day fairgrounds that, a half century later, became the new Japanese contributed Opera House. Actually, some of the exhibit building remain. Today, these are the Nile Hall (Saray an-Nil) and Al-Mustadira (Artists' Synicate Building) that shows works by contemporary artists, and Saray an-Nasr, where the Museum of Modern Egyptian Art is located. Other attractions include the Ministry of Culture's Akhenaten Gallery that is housed in a villa on Maahad as-Swissri street, the Italian Cultural Center and a museum housing the works of Mahmud Mukhtar, one of Egypt's internationally known artists.
Prior to World War II, and ever since the construction of the original Gezira Palace in 1866, the island was almost exclusively known as Gezirat Boulaq (Boulaq Island). The name Boulaq came form thriving port by the same name on the Nile's eastern bank. During this time period there was a small bridge linking the island's midsection to Giza, along with the street that intersected the island's middle named Zamalek. This street later became Avenue Fouad, and after 1952 took its present name, 26th of July Avenue.
Actually, the bridge and street borrowed the name, Zamalek from a small village in Giza called Al Zamalek. This village was just southwest of Imbaba Village, and it is thought that the meaning of Zamalek derives from Zomlok, a Kurdish word meaning straw hut.
After World War II, during a time that Egypt remained under British control, the island's population grew rapidly. Soon the area north of 26th of July Avenue was commonly referred to as Zamalek, while the midsection of the island was referred to as Gezira Al Wasta. However, soon, the entire island became known as Zamalek. However, older residents even today sometimes refer to the area south of 26th of July Avenue as Gezira, but this is mostly due to the Gezira Sporting Club located there and established by the British in 1883. The opulence of the 1920 and British rule can be seen in the Amr Ibrahim House, located just opposite the main exit gate of the club.
Even after World War II, the island's northernmost area was marshy and would completely disappear during high floods, therefore being mostly uninhabitable. The area was later built up, and due to the Great Dam at Aswan, no longer suffers this fate.
Today Zamalek is a thriving center for middle and upper class Egyptians, along with foreign dignitaries (there are more embassies in Zamalek than any other district of Cairo) and many tourists. It remains one of the most pleasant areas of Cairo. Indeed, it is Cairo's most fashionable residential district where one will find the BMW's and Mercedes of rich Egyptians, supermarkets that sell sushi or French pastries and always an upbeat take on Egyptian life.


T.Love is a Polish rock/pop band that was founded in 1982 in Częstochowa. Originally called Teenage Love Alternative, they chose an interesting time to start the band—during martial law. The four original members, Zygmunt (Muniek) Staszczyk (vocals, bass), Janusz Knorowski (electric guitar), Dariusz Zajaç (keyboard), and Jacek Wudecki (drums), were all in high school together, and their first appearance was at a local music festival.
In 1984 T.Love started giving out cassettes to their fans at their concerts—they were very popular at the Jarocin Festival—but could not officially record or release albums until 1987. At that point they changed their name to T.Love and, with a somewhat different lineup, recorded their first album. After that the band's composition changed almost continually for several years, although they managed to release a few more albums during this turmoil—mostly rock, but with some reggae influences. Some of their later albums departed from this tradition, notably 1996's Al Capone, which included some disco stylings, and 1997's Boys Don't Cry (Chłopaki nie płaczą), which was in (or made fun of) the boy-band style. After that, they went more pop.
The band is still touring, performing, and recording, and they celebrated their 30th anniversary in 2012, although only one original member, Staszczyk, remains. The other current members are Maciek Majchrzak (guitar), Janek Pęczak (guitar), Paweł Nazimek (bass), Tom Pierzchalski (saxophone), Michał Marecki (keyboard), and Jarek Polak (drums). Of the ten studio albums they've already released, five have gone gold and one platinum; they are planning to release a new album in late 2016.
Skąd bierze się ten jazz?