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Area forecast discussion 
National Weather Service Houston/Galveston Texas 
830 PM CST Tuesday Dec 2 2008 


Update... 
current package is looking good for tonight. Made only very minor 
tweaks to the grids...primarily was to lower mins in the northeast 
counties based on current trends where temperatures are down to the middle 
50s already. Modification underway and dewpoints been creeping 
upward but looking at 00z crp sounding the atmosphere has a long 
way to go. 


45 


&& 


Previous discussion... /issued 536 PM CST Tuesday Dec 2 2008/ 


Discussion... 
00z taf/aviation discussion... 


Aviation... 
VAD winds from the 88d show a decent low level jet with winds around 
30-35kts. This should strengthen some tonight but winds should 
continue to mix down. There may be some slight low level wind shear to deal with 
but not enough to warrant putting in the taf. Still if the low level jet 
increases more than expected...will amend accordingly. Moisture 
return is a bit of a concern given MVFR ceilings are expected in the 
model data. Given strong mixing with the low level jet...tafs will keep a 
broken 2000ft deck (near 925mb where boundary layer moisture should 
be the greatest) starting around 09z tomorrow morning. Expect 
more of a broken 2-4000ft deck to continue through the day as low level jet 
remains in place. Winds should mix down by late morning and 
continue through the afternoon. Kiah 30 hour taf will indicate 
possible frontal passage between 03z and 06z Wednesday night. Also will indicate 
at least a chance of showers maybe a shot at thunderstorms and rain but this will 
depend on boundary layer moisture. 


39 


Previous discussion... /issued 300 PM CST Tuesday Dec 2 2008/ 


Discussion... 
surface high pressure has moved off to the east and a strong 
pressure gradient is setting up across central Texas. Winds will 
remain on the strong side tonight and Wednesday ahead of an 
approaching cold front. Due to higher dew points and mixing...feel 
min temperatures will be about 20 degrees warmer than last night. Temperatures 
will fall this evening and then probably slowly rise toward 
morning as clouds begin to develop and thicken. 


A cold front will cross the region on Wednesday night...between 04z 
and 08z. Moisture levels don't look great with precipitable water values 
approaching 1.1 inches. Middle-level capping is also evident and the 
cap won't erode until Wednesday night as the upper trough moves 
across the Southern Plains. Storm Prediction Center has the area in see text for Wednesday 
night. The area will lie in a right rear quadrant on Wednesday night and 
would go with higher probability of precipitation if moisture levels were higher. Still... 
with frontal forcing and some upper level support...high end 
chance probability of precipitation look reasonable. Forecast soundings and cross sections 
show limited moisture on Thursday...so will keep things mostly 
clear. Models hint at additional moisture on Friday so will keep 
things mostly cloudy. A deep upper level trough will keep cold air 
over the region Thursday and Friday with some moderation Saturday 
and Sunday. The next upper level trough and cold front will 
approach the region next Tuesday. 43/31 


&& 


Preliminary point temps/pops... 
College Station (cll) 57 78 42 62 37 / 0 20 20 10 10 
Houston (iah) 58 76 45 64 37 / 0 20 40 10 10 
Galveston (gls) 61 71 53 62 50 / 0 20 40 10 10 


&& 


Hgx watches/warnings/advisories... 
Texas...none. 
GM...small craft should exercise caution through Wednesday afternoon 
for the following zones: Galveston Bay...Matagorda Bay. 


Small Craft Advisory until 6 PM CST Wednesday for the following 
zones: waters from Freeport to the Matagorda Ship Channel 
20 nm to 60 nm...waters from Freeport to the Matagorda Ship 
Channel out 20 nm...waters from High Island to Freeport 20 
to 60 nm...waters from High Island to Freeport out 20 nm. 


&& 


$$ 


Discussion...45