Autumn arrives across the Northern Hemisphere at 4:18PM CDT today, signaling a transition from the hot, steamy days of summer to the arrival of cold fronts across the Gulf of Mexico. In fact, the first such cold front will reach the northern Gulf today. It’s weak, but it’s a sign of things to come. In another week or two, cold fronts will begin moving out across the Gulf of Mexico and off the Southeast U.S. Coast weekly. With each passing cold front, wind shear and dry air will spill out across the Gulf of Mexico and Southwest Atlantic, diminishing the chances of tropical development in the region and gradually bringing the 2009 hurricane season to an end.
To say that the 2009 hurricane season has been quiet would be an understatement. Except for a brief burst of activity in late August and early September, the Atlantic Basin has been quite a hostile environment for tropical cyclones. Only Bill and Fred would be able to find a small area of favorable conditions to allow each to become a hurricane. The other four named storms, Ana, Claudette, Danny and Erika, would struggle as weak, sheared tropical storms. Both hurricanes reached major hurricane intensity, but only Bill made landfall in a much-weakened state over eastern Newfoundland.
Is the 2009 season over? I think it’s a little too early to make such a statement. Last year, major hurricanes Omar and Paloma developed in the Caribbean Sea in October and November. But the Caribbean has been dominated by high wind shear and sinking air since June, and there’s no sign that the environment is changing as of late September. There may be periods over the next month when wind shear will relax enough across the Gulf of Mexico or the Southwest Atlantic east of the Bahamas to allow for something to develop. The steering currents of late September through October typically would take late-season developments either toward the northeast Gulf (Florida), the East U.S. Coast, or the northern Caribbean.
I think that another 1 or 2 named storms will probably develop over the next 3-4 weeks and that will be it for 2009. The 2009 hurricane season will be one of those seasons that no one remembers, and that’s not a bad thing.
