Forecasters predicted a wintry mix of snow and sleet would coat downtown Houston with about an inch of accumulation.  Heavier snowfall -- up to 3 inches -- will blanket areas west of the city.  In New Orleans, forecasters predicted mostly rain with a sleet mix in the city's northern districts and outlying neighborhoods.  Louisiana Gov. Bobby Jindal declared a state of emergency Thursday in anticipation of the weather, activating the state's Crisis Action Team to monitor possible hazardous conditions that could affect parts of the state over the next few days.  State government offices in 55 Louisiana parishes will be closed on Friday because of the wintry weather.  Southwest Airlines canceled all flights to Corpus Christi, Harlingen, and Houston Hobby airports in Texas, according to company spokesman Marilee McInnis. The carrier called off a total of 157 flights on Thursday, she said.  Light snow accumulations ranging from less than an inch of snowfall in Dallas to heavier amounts to the south and east raised questions as to whether inclement weather would impede Super Bowl travelers.  Green Bay Packers fans in north Texas ahead of their team's showdown with the Pittsburgh Steelers got only a relative respite, temperature-wise, from what they usually experience up in Wisconsin.  In Arlington, Texas, site of Sunday's game, a wind-chill advisory was in effect due to very cold conditions that made the temperature feel between zero and 10 degrees below, and several inches of snow and ice had a debilitating effect in parts of Dallas, Fort Worth and surrounding areas.  "It was funny to see a whole city shut down. Everything was closed," said Packers' defensive lineman Ryan Pickett. "In Green Bay, this is just a normal day."
A swirl of sleet and freezing rain barreled into the Gulf States Thursday, yet another winter storm carrying frigid weather to a region unaccustomed to the cold.The storm system extended from Corpus