Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 091113
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
513 AM CST Fri Dec 9 2016

.AVIATION...
VFR ceilings expected through mid afternoon with the deck then
scattering out. Winds will be the main issue today. Breezy north
winds will become northeasterly and diminish 15Z to 17Z for most
inland sites. KLBX will be a bit slower to respond and KGLS
should see about 14 knots through the afternoon period. With
clouds thinning out, freezing temperatures once again expected
tonight over the northern sites - KCLL, KUTS, KCXO - and possibly
at KIAH. Incoming VFR cloud cover may help alleviate temperature
concern at KIAH.

40

&&

.PREV DISCUSSION... /ISSUED 400 AM CST Fri Dec 9 2016/

DISCUSSION...
At 300 AM, surface high pressure was located over central
Oklahoma. A tight pressure gradient continued over the western
Gulf and impinged on the coastal counties. An upper level
disturbance brought some very light rain to the area last night
but more importantly, the system kept clouds in place limiting the
temperature drop. Where skies have cleared (Crockett),
temperatures are already at 30 degrees. But further south, clouds
have hung in and temperatures are still in the mid/upper 30s. Will
let the Freeze Warning ride as satellite imagery is showing a few
breaks and the cloud shield is slowly eroding from the north.
Clouds will gradually thin today and the area should receive some
sunshine later today as high pressure moves toward Missouri.
Despite some sun, cold air advection will continue albeit weaker
than yesterday but daytime highs today will struggle to reach 50
degrees. The surface high shifts far enough east tonight and
Saturday for onshore winds to redevelop. Not sure the magnitude of
the onshore wind will be sufficient to mitigate another night of
near freezing temperatures. The best potential for freezing temps
will be in areas that have already experienced freezing
temperatures and freeze warnings have already been issued for
those areas so no additional freeze warning is expected for
tonight.

Warm air advection will begin on Saturday as a weak warm front
tries to develop. Fcst soundings show saturation deepening from
the sfc to around 850 mb. Would not be surprised if a few showers
began to develop as early as Saturday aftn but more likely
Saturday night and Sunday as the warm front moves north. The GFS
and ECMWF both show a weak s/wv late Sunday and Sunday night nd
this feature should generate some additional showers across most
of the region. A weak cold front will approach the region early
Monday and there will enough convergence along this feature for
another slight chance of showers especially over the eastern half
of the region where deeper moisture is available.

850 mb temps really warm on Mon/Tues and max temps could approach
the upper 70s on both afternoons. Things become a bit more muddled
by the middle of next week as another strong cold front will cross
the region. Still some timing differences between the now slower
GFS and the faster ECMWF. Yesterday, the EC was slower and the GFS
faster. Still both models are showing the front but differ in the
timing and available moisture. Used a blend of model solutions
given the uncertainty of the pattern evolution. 43

MARINE...
Strong cold air advection and a tight pressure gradient continue to
lead to gale force winds mainly over the offshore waters early this
morning. Guidance and models have the winds diminishing below gale
force by mid morning. However, advisory conditions will likely
persist over the offshore waters through mid afternoon. Closer to
the coast within 20 nm, advisory conditions will probably let up by
around midday.

Winds will swing around to out of the east later this afternoon and
persist through tonight. On Saturday moderate onshore winds will
develop with caution conditions likely at least over the offshore
waters both Saturday and Sunday. A weak front is expected on Monday
with a stronger front moving off the coast during the mid week
period -- model differences suggest either Wednesday or early
Thursday morning.

40

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)      47  32  52  49  70 /   0  10  10  40  30
Houston (IAH)              48  34  54  51  73 /   0   0  10  30  30
Galveston (GLS)            50  46  60  60  71 /   0  10  10  20  20

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...Freeze Warning until 9 AM CST this morning for the following
     zones: Austin...Brazos...Burleson...Colorado...Grimes...
     Harris...Houston...Liberty...Madison...Montgomery...Polk...
     San Jacinto...Trinity...Walker...Waller...Washington.

GM...Small Craft Advisory until 6 AM CST early this morning for the
     following zones: Galveston Bay...Matagorda Bay.

     Small Craft Advisory until noon CST today for the following
     zones: Coastal waters from Freeport to the Matagorda Ship
     Channel out 20 NM...Coastal waters from High Island to
     Freeport out 20 NM.

     Small Craft Advisory until 3 PM CST this afternoon 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.

     Gale Warning until 6 AM CST early this morning 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...43
Aviation/Marine...40



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