Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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116
FXUS64 KHGX 092143
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
343 PM CST Fri Dec 9 2016

.DISCUSSION...
Temperatures today have made it into the mid 40s to low 50s along
the coast. Visible satellite imagery is showing some cloud cover
moving over the region from the W/SW. Temperatures did drop below
freezing north of Houston mainly away from any big towns. Given
the latest observations it looks like Houston, Trinity, Walker and
Madison counties had widespread freeze so they will not be
considered in future freeze warnings.

Speaking of freeze warnings, there are no plans to issue a freeze
warning for tonight although that could change. The only areas
that could observe a freeze will be Montgomery, Liberty, San
Jacinto and Polk Counties. Temperatures could drop to 28-32F in
these areas but may only do so for a few hours. The main concern
for temperatures tonight will again be cloud cover. Visible
satellite shows clouds increasing from the SW which looking at
isentropic analysis from short range models seems to be rooted in
moisture advection in 290-295K layers. Latest RAP/NAM seem to have
the better handle on the cloud cover than other models at this
time so think cloud cover will keep temperatures from dropping too
much. But temperatures could drop quickly before cloud cover
thickens over these areas.

Models are in pretty good agreement over the weekend with a
warming trend. High temperatures should reach the 50s Saturday and
likely continue to increase overnight into Sunday as a warm front
pushes north early Sunday. Warm advection pattern will support
showers with the increase in gulf moisture over the region.

A fast moving short wave trough should move across the Plains
Sunday into Monday. A front should push into the area on Monday
but may stall across the area instead of pushing into the Gulf.
Front would then likely dissipate with more return flow Tuesday
into Wednesday. As we have been discussing the last couple of
days, the upper level pattern remains somewhat zonal across the
U.S. mid week with a split in the jet over the north Pacific
causing a strong diving jet over W Canada. This should allow for
more cold airmasses to move down from Canada but the ECMWF/GFS
have very different solutions and continue to flip at time. The
ECMWF has one surge of cold air on Wednesday but it mainly stays
north and east of Texas. GFS tries to bring in this colder airmass
on Thursday where the ECMWF is slower to do so with a re-enforcing
cold airmass. GFS brings a good surge of cold air down the plains
end of next week while the ECMWF keeps it bottled up over the
plains and develops a broad trough over the Great Basin/4 Corners.
Forecast hedges a bit towards the ECMWF solution as there is not a
lot of confidence in the GFS being able to resolve these cold
shallow airmasses this far out in the forecast.

Overpeck

&&

.MARINE...
Moderate NE flow will continue to gradually slacken this evening. A
Small Craft Advisory remains in effect for the offshore waters
through 9 PM CST this evening as winds continue to gust over 20 kts
and seas remain near 7 to 9 feet.

Northeasterly winds this evening will gradually become easterly by
Saturday before becoming moderate southerly on Sunday. A SCEC will
probably be needed Saturday night into Sunday as winds increase to
15-20kts. A weak front is expected on Monday with a stronger front
moving off the coast sometime during the midweek period.

11

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)      33  55  50  72  60 /  10  10  30  30  10
Houston (IAH)              35  55  51  74  64 /   0  10  20  30  30
Galveston (GLS)            45  60  60  71  66 /  10  10  10  20  30

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...Small Craft Advisory until 9 PM CST this evening for the
     following zones: Waters from Freeport to the Matagorda Ship
     Channel from 20 to 60 NM...Waters from High Island to
     Freeport from 20 to 60 NM.

&&

$$

Discussion...39
Aviation/Marine...11



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