First true cold front being forecasted for later this week 9/21/09

[ticka1]

Various news outlets and Jeff Lindner are forecasting the first cold front for the SE Texas area later this week.

If it happens temps will be in the low 60's - upper 50's at night and during the day - the 70's. I can't wait. Turn the a/c off and enjoy the cool refreshing air.

Usually with the first cold front that puts us out of hurricane danger and rolls us into the Fall/Winter Season for SE Texas. With El Nino - we might have a better wishcasting chance of snow!!!!

More to come as the timing gets closer.

[ticka1]

Email from Jeff Lindner 9/21/09:

Much advertise cold front will move into SE TX Tuesday and then stall across the region with heavy rainfall possible Tuesday-Thursday.

Moist air mass resides across the area with PWS in the 1.8-2.0 inch range. Given a little additional heating expect to see a scattering of shower develop…as we already see in Wharton and Fort Bend Counties. Cold front drops southward tonight and enters the area on Tuesday as PWS rise in the 2.0-2.3 inch range. Lift along the front will be significant and expect widespread showers and thunderstorms. SE moving boundary begins to slow as it moves into the region leading to the increased threat for cell training as the front becomes increasingly parallel to the upper level winds. Not all that confident on where the boundary will end up stalling out as the models show varying solutions with the NAM offshore and the GFS inland along the coast. For now will take the difference and indicate the surface boundary making it south of US 59, but remaining just inland…the boundary could be forced off the coast by outflow boundaries. 850mb front hangs up between Victoria and Houston to Austin and College Station. Extensive moisture will ride up and over the frontal slopes as an upper level storm system over CO induces WSW to SW upper level flow atop the cooler air mass at the surface. Expect widespread rains to continue in the post frontal air mass with the heaviest rains focused along the boundaries in the area.

Sub-tropical jet stream will help induce coastal surface reflection on the front along the middle TX coast around Rockport. This will greatly enhance lift Wednesday as this feature moves NE along the surface front. Expect the heaviest rains to focus Tuesday with the frontal passage and then near the coast Tuesday night into early Wednesday before shifting back northward late Wednesday.

Given the very moist air mass, surface boundary, and threat for cell training…the excessive rainfall and flooding potential will be on the increase. Not ready to bite on the very aggressive QPF model forecast and will go with the toned down amounts of a widespread 1-3 inches with isolated 3-5 inch amounts. We will see how meso-scale trends play out on Tuesday and better define where the threat will be the highest to see if QPF amounts should be higher in some areas. Current thinking is that the heavier amounts may focus more down toward Matagorda Bay.

Given weak colder air advection, clouds, and rain temps. will hover in the 70’s from Tuesday into Wednesday. Some locations in N TX may see overnight lows drop into the 50’s…longer range models show another potential front entering the area late this week to scour out the moisture in time for next weekend.