4:57 p.m. | Updated After several years of relatively somnolent hurricane seasons in the Atlantic Ocean, conditions have aligned to create a heightened storm threat this summer and fall. If the season plays out as forecast, this will almost certainly complicate the months-long effort needed to insure the closure of the gushing seabed oil well and limit the spread of resulting slicks. (The Pacific and Atlantic often have opposite patterns of storminess and, sure enough, the forecast in the eastern Pacific is for a below-normal season.)  The National Oceanic and Atmospheric Administration issued its initial hurricane forecast for the Atlantic Ocean and Gulf of Mexico this afternoon, predicting an “active to extremely active” hurricane season.  This is what such a season looks like (the map shows tracks of all the tropical storms, including hurricanes, in 2005):  In this year’s Atlantic storm season, which begins June 1, the agency calculated a 70 percent probability of 8 to 14 hurricanes. “If this outlook holds true, this season could be one of the more active on record,” said Jane Lubchenco, the agency administrator and under secretary of commerce for oceans and atmosphere. “The greater likelihood of storms brings an increased risk of a landfall. In short, we urge everyone to be prepared.”  [5:19 p.m. | Updated Below you can also read about new federal research concluding that strong hurricanes don't just pose a threat on the surface of the Gulf of Mexico, but could threaten some of the thousands of miles of pipelines crisscrossing parts of the seabed in relatively shallow waters.]  Here’s the ocean and climate agency’s summary of factors influencing the forecast:  - Upper atmospheric winds conducive for storms. Wind shear, which can tear apart storms, will be weaker since El Niño in the eastern Pacific has dissipated. Strong wind shear helped suppress storm development during the 2009 hurricane season.  - Warm Atlantic Ocean water. Sea surface temperatures are expected to remain above average where storms often develop and move across the Atlantic. Record warm temperatures – up to four degrees Fahrenheit above average – are now present in this region.  - High activity era continues. Since 1995, the tropical multi-decadal signal has brought favorable ocean and atmospheric conditions in sync, leading to more active hurricane seasons. Eight of the last 15 seasons rank in the top 10 for the most named storms with 2005 in first place….  The role of global warming in shaping hurricane numbers and strength remains complicated, with the latest work pointing in the Atlantic to fewer storms overall but a higher proportion in the strongest, most destructive categories.  Postscript: Scientists at the Naval Research Laboratory, analyzing seabed currents and mud movement after the passage of Hurricane Ivan in 2004, have concluded that the underwater turbulence from hurricanes could be severe enough to cause mudslides and possibly imperil pipelines on the seafloor in shallow regions of the Gulf of Mexico. The study is scheduled to be published on June 10 in the journal Geophysical Research Letters.  Here’s a portion of a news release issued by the American Geophysical Union, which publishes the journal:  Using a computer model of wave-induced current stresses, the team estimated how powerful currents would need to be for forces they exert at the sea floor to exceed a “critical force” that triggers sediment suspensions and could lead to underwater mudslides.  According to these estimates, hurricanes considerably weaker than Ivan, which was Category 4, could still tear up the seafloor, causing significant damage as deep as 90 meters.  The researchers were surprised by how long the destructive currents persisted after Hurricane Ivan passed by. “The stress on the sea floor lasted nearly a week,” says Hemantha Wijesekera, lead author of the study. “It doesn’t go away, even after the hurricane passes.”  The researchers say they’re not sure what strengths of forces underwater oil pipelines are built to withstand. However, “hurricane stress is quite large, so the oil industry better pay attention,” Wijesekera says.
A potentially "extremely active" hurricane season in the Atlantic Ocean poses a threat to the gulf oil cleanup.