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Area forecast discussion 
National Weather Service Houston/Galveston Texas 
548 PM CST Friday Nov 20 2009 


Update... 
00z taf discussion. 


&& 


Discussion... 
upper level trough still out in West Texas so as it moves east 
tonight...southeast Texas should still have ongoing rain moderate at times. 
Thunderstorms should not be an issue. Tafs will keep ceilings in the 
MVFR/IFR levels through 18z and then a gradual lifting of 
ceilings as the upper trough clears southeast Texas. Winds should also turn 
more to the north tomorrow but remain below 10 kts as surface ridge 
develops over the arklatex. Will monitor radar trends tonight and 
amend taf for any heavier precipitation that may affect terminals and 
cause lower visibility. 


39 


&& 


Previous discussion... /issued 312 PM CST Friday Nov 20 2009/ 


Discussion... 
upper trough is currently pushing into cntl Texas and anticipate this 
to eventually push east of southeast Texas Sat morning. Will see periods of 
light to occasional moderate rainfall push through overnight until 
the trough axis moves off to the east. Haven't seen a well defined 
surface low develop as models have been pinging on for days as of yet 
which has probably kept quantitative precipitation forecast totals in check. Although areas south of 
I-10 have seen 1-4 inches of rain in the past 12-18 hours think 
the vast majority of the watch area can take another couple inches 
without any major issues (other than the typical localized problem 
spots). Plan on letting the Flash Flood Watch expire at 6 PM. May 
still see some minor coastal flood issues at high tide this 
evening. Updated coastal Flood Warning will be out in a while. 


Clouds will begin clearing from west to east during the day Sat. 
Rest of the weekend looks nice with surface high pressure filling in from 
the NE behind the departing trough. Onshore flow resumes late sun or 
Monday as pressures fall in the plains. Next trough drops down into the 
plains & Midwest early next week. Associated front should push 
through the area Tuesday with a reinforcing surge later in the week. As 
of now...Thanksgiving looks dry with highs in the 60s & lows in 
the 40s. 47 


Marine... 
strong east winds continuing over the coastal waters this afternoon in 
response to the developing storm system over SC Texas. While the 1st 
round of precipitation has left the area...another batch is moving off the 
the Lower/Middle Texas coast at this time. So will be keeping the Small Craft Advisory across 
our entire marine zones through the overnight hours. Otherwise not a 
whole lot of changes in the Post storm/frontal regime (with light 
offshore winds Sat/most of sun). The next front still prognosticated for 
a Tuesday frontal passage. 41 


Aviation... 
timing of the next batch of precipitation one of the main issues with this 
next set of tafs. But from the looks of it we should be well into 
the area of sh/thunderstorms and rain showers by the time the next set is due so it should 
when all of this ends as the problem. GFS the preferred model for 
the track of the upper low/associated surface winds but so far it has 
not been that great with precipitation for the tafs. And so will likely be 
sticking with extrapolation/trends as our friend in the shortterm. 
41 


&& 


Preliminary point temps/pops... 
College Station (cll) 64 51 66 46 70 / 80 60 20 0 0 
Houston (iah) 67 52 66 46 70 / 80 60 50 0 0 
Galveston (gls) 70 57 66 54 69 / 90 60 40 0 0 


&& 


Hgx watches/warnings/advisories... 
Texas...Flash Flood Watch until 6 PM CST this evening for the following 
zones: Austin...Brazoria...Chambers...Colorado...Fort 
Bend...Galveston...Harris...Jackson...Matagorda...Waller... 
Wharton. 


GM...Small Craft Advisory until 4 am CST Saturday for the following 
zones: Galveston Bay...Matagorda Bay...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...39