Tropical Depression Update – 245 pm

The first tropical system to threaten the Gulf Coast this season is slowly developing in the Southwest Gulf today. Note that the storm is very asymmetrical…with most of the storms and clouds to the north and east of the center. With such disorganization, and an expected landfall within 48 hours somewhere between Houston and Biloxi (big range), the storm may not even become a named tropical storm, but if it does it would be Claudette. It will bring some winds, and a lot of rain, to the Gulf Coast, including the AL and NW FL beaches from Mobile to Panama City, but should not be a big wind or storm surge threat.

ECMWF model

We don’t have too much guidance from hurricane models because of the disorganization, but global models like the Euro (above), and the GFS take the storm up into Louisiana/Mississippi/north Alabama/north Georgia then into the Carolinas by Sunday evening. Note the trough of low pressure in the Mississippi River valley and Great Plains Sunday evening. That is a cool front moving in…and it will help keep the storm moving northeast and should prevent any major flooding over most of the Southeast. NCEP rainfall totals are maximized to the right of this general track (as they usually are). Some coastal areas may get rainfall totals over 7″, and rainfall of 3 to 5″ is expected across central and southern MS and AL, and parts of GA. So, some flash flooding is possible, and we have to consider the unpredictability of weak tropical systems.

NOAA total rainfall through Tuesday

If the center of the storm moves through MS and AL Saturday and Saturday night, there may be a threat for a few small tornadoes, mainly across northern Florida and the southern half of Alabama, due to wind shear east of the system. The energy-helicity index, a composite of shear and instability available for tornadoes, is expected to be sufficient for small tornadoes Saturday night and Sunday morning.

(pivotalweather.com)

For the Birmingham area, expect nice weather again tomorrow, but then increasing clouds and thunderstorms moving in on Saturday, continuing off and on Saturday night into Sunday. Some areas around here could get over 4″ of rain in locally heavy thunderstorms, but unless the track is drastically different than what we are seeing now, major river flooding should not be an issue. Just a stormy, breezy weekend. If you are headed to the beach, it will be a weekend of storms, wind, and rough seas, then probably improve starting Monday.

Dr. Tim Coleman

Consulting Meteorologist

Coleman and Knupp, LLC

http://www.colemanandknupp.com

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