Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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744
FXUS64 KHGX 270449
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1149 PM CDT Wed Jul 26 2017

.AVIATION...
VFR conditions are expected; although, there is a slight chance
for MVFR conditions around 12Z especially at KCXO. The latest run
of the GFS was drier due to the upper level high pressure ridge
showing signs of developing overhead from the Southern Plains.
However, do not think the ridge will do this until Thursday night
and Friday. The model QPF still showed some output over the
central and coastal sites. For this reason, kept a slight
potential for isolated showers and thunderstorms once again on
Thursday, mainly after 15Z at the coast and after 18Z further
inland to KIAH and KCXO.

40

&&

.PREV DISCUSSION... /ISSUED 845 PM CDT Wed Jul 26 2017/

DISCUSSION...
A weak 850 mb high was located over south central Louisiana and
850 temps were 1-2 degrees warmer tonight and moisture levels at
850 mb were a bit lower than last night. 00z soundings showed PW
values near 1.56 inches at LCH and moisture was lacking in the
850-700 layer. The 00z CRP sounding showed PW values around 1.73
inches. GOES-R PW imagery shows the high PWAT air over SE TX is
being shunted westward with drier air working into the region from
the east and the south. At 300 mb, a sprawling ridge of high
pressure extended from eastern AZ into western AR with a lobe of
the upper high extending south into LA. A weak inverted upper
trough extended from SE TX into Deep South Texas. So what does it
all mean? The drier air working into the region and the loss of
heating should keep things dry overnight with generally clear
skies. Not enamored with rain chances for Thursday as moisture
levels drop further and the inverted upper trough pushes west and
becomes less defined. However, am concerned with afternoon max
temps and heat index values. The proximity of the upper ridge and
warm 850 temps suggest high temps between 95-100 and heat index
values between 105-109 degrees tomorrow afternoon. A Heat Advisory
may be required for tomorrow afternoon. Not seeing a lot of
change for Friday and Saturday with very warm temperatures and
high heat index values. Will tweak Temp/Sky and Dew Pt grids but
the overall integrity of the previous forecast is on track. 43

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)      76  99  76  99  77 /  20  10  10  10  10
Houston (IAH)              77  96  78  97  78 /  20  10  10  10  10
Galveston (GLS)            84  92  82  91  83 /  20  20  10  10  10

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&

$$

Discussion...43
Aviation/Marine...40



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