Tropics Are Heating Up

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A DIVIDED ALABAMA: We have a huge contrast in weather across Alabama this afternoon. The northwest counties are in dry air, the sun is shining, and humidity values are much lower. Muscle Shoals has a bright, sunny sky with 83 degrees, and low dewpoint of 61. But, the dry air did not make it as far as expected, and today’s forecast was a bust for places like Tuscaloosa, Birmingham, and Anniston. Instead of lower humidity, these cities dealt with some rain this morning, and just a few peeks of sun this afternoon in spots. Dry air just has a hard time going deep into Alabama in August, despite what computer models might suggest.

TOMORROW AND FRIDAY: Moist air will move back into that part of Alabama that enjoyed drier air today, so we will need to mention a chance of showers and thunderstorms on both days. There is no real evident forcing mechanism other than a broad upper trough to the west, so I don’t think it will be an “all day” rain either day. In fact, the sun might peek out at times. But, just be aware a passing shower or storm is possible at just about anytime both days. Temperatures remain well below average, with highs in the low to mid 80s.

OUR WEEKEND: A tricky, if not impossible forecast due to the uncertainty involving the tropical system that will be in the Gulf of Mexico in a day or two. Models are split between two solutions (see the tropical discussion below), and if the system does move up toward the Central Gulf, it is not clear if the circulation center will pass east, or west of Alabama. The 12Z GFS is in good agreement with the NCEP precipitation guidance, showing a broad tropical low moving into the Apalachicola area Saturday, with the axis of the heaviest rain over the Florida Panhandle, Southeast Alabama, and South Georgia.

We will just have to mention a “chance” of showers and storms Saturday and Sunday, and we will fine tune the forecast as we get better clarity on our tropical system.

GULF COAST WEATHER: Pretty much the same story; the forecast for Friday and the weekend will be determined by the tropical system. For tomorrow and Friday, we expect only about 1 to 3 hours of sun each day with scattered to numerous showers and storms. It won’t rain the entire time, but you will certainly be wet at times. Highs in the 80s.

The rain could become heavy and widespread on the Gulf Coast Friday night into Saturday, but there is no way now to resolve where the heaviest rain will be at this point. A pretty decent chance conditions begin to improve on the coast by Sunday or early next week.

TROPICS: Very active; one tropical wave in the East Atlantic should become a tropical depression over the next 24 hours, but the one to watch for us is over the Caribbean.

The Caribbean wave is developing a nice CDO (central dense overcast), and with good banding features, meaning it should be upgraded soon to a tropical depression. It will move into the southern Gulf of Mexico late this week, and from there nobody knows where this goes for now. Models are in two camps… one set, including the NAM and the GEMS, takes the system slowly toward Mexico, or the southern tip of Texas early next week. The other camp, including the GFS, and the HWRF, bring it up toward New Orleans, Mobile, Pensacola, or Apalachicola over the weekend.

I believe the Central Gulf solution is the best bet for now. A decent chance this becomes a tropical storm, but more than likely the main impact will be from heavy rain and flooding since hostile upper air winds should prevent hurricane formation. NCEP shows the axis of heavier rain from the Florida Panhandle up through southern Georgia and into South Carolina, with potential for 3-6 inches of rain in this zone. Maybe more in spots.

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I had a great time today on the Mississippi State University campus… I spoke to the annual summer workshop for distance learning students. Special thanks to Renny and Greg for lunch at the Little Dooey.

Look for the next Weather Xtreme video here by 7:00 a.m. tomorrow….

Tags: showers

Category: Alabama's Weather