Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 211130

Area Forecast Discussion
National Weather Service Houston/Galveston TX
630 AM CDT Mon Oct 21 2019

.AVIATION [12Z TAF Issuance]...

Cold front pushing through the region is bringing thunderstorms,
MVFR to IFR CIGs, and strong winds. It has already moved through
CLL and UTS, currently moving through CXO, will be moving through
Houston very shortly, and finally reaching GLS by 14z. Out ahead
of the front there are some scattered thunderstorms impacting the
southern TAF sites. After the front, a northerly wind takes over
with some lingering lower clouds, but by the afternoon VFR
conditions will prevail at all TAF sites.



.PREV DISCUSSION /Issued 415 AM CDT Mon Oct 21 2019/...

.SHORT TERM [Today Through Tuesday Afternoon]...
Main story this short term will be the cold front that pushes
through the region today. The leading edge of the cold front will
reach the Houston-Burleson county axis within the next few hours and
with it a line of thunderstorms. Some of the storms embedded in this
line could be severe with the main threat of strong winds (and a
marginal tornado chance). The chance of some strong storms will not
only be with the line, but also pop-up storms ahead of the front.
Radar is already starting to come alive in Wharton County up towards
Grimes County as of 3 AM. Some of these storms may become
supercellular as NAM and RAP soundings have CAPE values of 2000 -
3000 J/kg, ESRH > 200 m2/s2, and effective nearing 50 - 60 kts. The
front reaches the city of Houston around 7 to 8 AM leading to a
potentially headache inducing morning commute (so give yourself a
little extra time this morning), then down to the coast by noon. The
front is moving at a pretty good speed, and rainfall rates will
mostly stay under an inch an hour (except under some isolated
downpours), and with relatively dry soils there is not much of a
flooding threat today.

Things quickly dry out after the front with dew points dropping into
40s by tonight. Highs today will be about 10 degrees cooler than
yesterday, so looks like we are done with the record heat for at
least a little bit. Clear skies and low dew points will allow most
of the area to dip into the mid 50s tonight. The weather is a bit
more mellow on Tuesday as high pressure builds over southeast Texas
with temperatures comparable to today.


.LONG TERM [Tuesday Night Through Monday]...
Surface ridging from Alabama to SETX Tuesday night will help keep
it cool and dry Wednesday. The ridge continues to slide east and
this will open the Gulf up Thursday morning with moisture surging
back into SETX and leading to the development of showers and
thunderstorms over the Gulf that feed northwest into the Matagorda
Bay region ahead of a cold front. Again the GFS/ECMWF differing in
how to handle the upper trough with the GFS being the more
progressive and the ECMWF leaving significant height falls over
NM. Rain chances increasing for Thursday night and Friday and will
maintain the trend of favoring the ECMWF (and ICON) trend of
maintaining the lower pressures over E TX and the Upper Texas
Coastal waters with much warmer temperatures until Friday night
than GFS based guidance. Eventually the surface low moves through
the area Saturday and drier weather arrives with Pacific
airmass/downsloping off of Mexican Plateau.

Showers and thunderstorms continue across the Gulf waters through
the afternoon ahead of an approaching cold front. Lightning, heavy
downpours, and gusty winds are possible with isolated stronger
storms. The strong southerly flow will continue over the next few
hours. Caution flags have been extended through the day today, but
the winds may weaken for a few hours just behind the frontal
passage, which looks to occur around noon to 1 pm. Moderate to strong
northerly flow takes over in the late afternoon, then approaching
advisory levels during the overnight period through Tuesday
afternoon. Light to moderate onshore flow returns midweek, but the
week looks to end with another frontal passage bringing a return to
the stronger winds.



The hot year continues with two more record high temperatures
again yesterday they just keep coming...Galveston 87 previously 86
in 2004 and College Station 94 previously 92 way back in 1892!



College Station (CLL)  77  51  79  51  79 /  40   0   0   0   0
Houston (IAH)          80  57  77  54  79 / 100   0   0   0   0
Galveston (GLS)        80  67  77  71  79 /  90  10   0   0   0



GM...SMALL CRAFT SHOULD EXERCISE CAUTION through late tonight for the
     following zones: Coastal waters from Freeport to Matagorda
     Ship Channel TX out 20 NM...Coastal waters from High Island
     to Freeport TX out 20 NM...Galveston Bay...Matagorda
     Bay...Waters from Freeport to Matagorda Ship Channel TX
     from 20 to 60 NM...Waters from High Island to Freeport TX
     from 20 to 60 NM.


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