Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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000
FXUS64 KHGX 231124
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
624 AM CDT SAT JUL 23 2016

.AVIATION...
VFR conditions are expected for the most part. The exception will
be a brief 1 to 3 hour period of patchy ground fog early this
morning near LBX and SGR due to recent history of the airmass and
agreement between the SREF and NAM12. A favorable flow aloft
combined with the seabreeze will help isolated showers and
thunderstorms to move inland later today and this afternoon. Best
chances will be to the east of the sites; however, felt chances
were good enough for a mention at KCXO, KIAH, AND KLBX. Isolated
showers will be possible at or near KGLS this morning.

40

&&

.PREV DISCUSSION... /ISSUED 414 AM CDT SAT JUL 23 2016/

DISCUSSION...
At 3 AM, surface high pressure was located over the northern Gulf
of Mexico and a weak trough of low pressure extended from E CO
into E NM. A weak 850 mb high was centered over eastern TX and a
plume of deeper moisture was over S AR into W LA and E TX. At 300
mb, a sprawling ridge of high pressure had shifted west and was
now centered over N NM. 500 mb heights have fallen between 10-20
meters over the last 24 hours. A weak upper low was spinning over
W TN/N MS. Water vapor imagery shows a weak disturbance south of
Louisiana and this feature is heading west and will likely arrive
into SE TX around noon. Radar is showing quite a bit of precip
over the western Gulf early this morning and none of the global or
short term models show this. The approaching disturbance coupled
with the deeper 850 mb moisture should yield scattered showers and
thunderstorms this afternoon over mainly the eastern half of SE TX
and near the coast. Fcst soundings show PW values peaking between
1.90 and 2.10 inches toward 00z. The GFS soundings show a weak cap
near 600 mb and a rather dry looking sounding. The NAM12 shows a
saturated layer between 850-700 mb and much greater instability.
Have leaned toward the drier GFS as the upper ridge still looks
close enough to the region to impart some subsidence.

Although PW values will still exceed 2.00 inches on Sunday,
forecast soundings don`t show much of a saturated layer and
soundings still show a weak cap between 700-750 mb. Convective
temps are around 91 degrees so not expecting much more than
scattered showers/storms over the eastern half of the CWA.

Monday and Tuesday look to be the two most favorable days for
rain. An inverted trough over the Gulf will push west and 500 mb
heights will lower to 589 DM. PW values surge to 2.35-2.55 inches
and forecast soundings show a deep saturated layer extending from
900 mb to 400 mb. Storm motion on Monday looks to be around 6 kts
so some locally heavy rain a possibility. Moisture levels drop on
Tuesday but the position of the 500 mb trough should still favor
high rain chances. The trough exits the region on Wednesday as
another upper level high builds over the SE U.S.. SE TX will lie
in a weakness with one upper high out west and the other over the
east. A weak trough will move across the central plains so
despite fcst soundings showing a building cap and lowering
moisture levels, feel some mention of precip is warranted.
Unsettled weather should persist into next weekend as the
weakness aloft remains over SE TX. Another upper level ridge of
high pressure will build over Texas during the first couple days
of August. 43

MARINE...
Another day of light winds will be accompanied by isolated morning
showers. This scenario will be repeated on Sunday. As the upper high
pressure area moves off to the west, an increase in the coverage of
showers and thunderstorms can be expected Monday and Tuesday. The
latest models show a favorable pattern for at least isolated showers
and thunderstorms during the mid week period as well.

40

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)      98  77  97  77  94 /  10  10  20  10  40
Houston (IAH)              97  79  96  79  92 /  20  10  40  20  60
Galveston (GLS)            92  82  92  81  89 /  20  30  30  30  60

&&

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

$$

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



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