Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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000
FXUS64 KHGX 071158
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
558 AM CST Wed Dec 7 2016

.AVIATION...
A tough forecast today as a mix of low clouds and fog will
dominate early with some breaks in the clouds this afternoon only
for more clouds to develop early this evening. IFR/MVFR cigs to
prevail this morning as moisture remains trapped beneath a strong
cap. Some heating should help mix down some drier air and probably
raise cigs to MVFR/VFR by afternoon. Winds will remain light and
variable today. Leaned toward the Texas Tech WRF precip fields
for tonight as moisture levels deepen. Should start to see some
showers this evening especially over southern TAF sites as fcst
soundings a deepening saturated layer beneath a stout cap.
Finally, a cold front will move through the region between 08-12z.
Winds will become N-NE in the wake of the front and winds will
increase significantly. 43


&&

.PREV DISCUSSION... /ISSUED 543 AM CST Wed Dec 7 2016/

UPDATE...
Light northeasterly winds have allowed for radiation fog to spread
into the upper Galveston Bay/ Houston Ship Channel north of Eagle
Point per webcams this morning. Have done a quick morning update
to add a mention of patchy dense fog to the ongoing forecast, with
fog expected to persist through 9-10 AM CST. A Marine Dense Fog
Advisory may be needed if conditions continue to deteriorate.
Dense fog may also be able to spread into extreme southeastern Harris
and northeastern Galveston counties as a result.

Huffman

PREV DISCUSSION... /ISSUED 440 AM CST Wed Dec 7 2016/

DISCUSSION...
One last day of relative warmth is expected for Southeast Texas
today before a strong cold front blasts across the region
tonight. Early morning surface analysis showed this front seeping
into the Northern Plains from Canada. Closer to home, another
round of patchy fog is ongoing this morning and expect this fog to
dissipate by mid-morning with heating. Low clouds spreading
across the region from the northeast should help mitigate against
dense fog development, but a few locations outside of this cloud
shield (or under any breaks in it) may drop below 1 mile at
times.

Isentropic upglide (295K surface) will increase across the region
from southwest to northeast through the day today ahead of the
approaching front. Wouldn`t be surprised to see a few light
showers develop near the Victoria Crossroads early afternoon and
spread into the western/southwestern counties through the
remainder of the afternoon as lift increases. Surface high
pressure sliding east of the region today will allow for some
meager moisture return as northeast surface winds this morning
become south to southeast this afternoon, with shower coverage
increasing this evening and tonight along and south of the Highway
59 corridor as a result. Because moisture return is so minimal
(precipitable water values around one inch), not expecting much
in the way of rain totals with most areas receiving less than one
third of an inch. Otherwise, expect highs this afternoon in the
mid to upper 60s under mostly cloudy to cloudy skies.

The cold front over the Northern Plains will push into Texas
later today, reaching College Station this evening, the Houston
metro after midnight, and clearing Galveston by sunrise. Wednesday
night`s showers will gradually be shunted offshore as the front
continues to push into the Gulf on Thursday morning. Thursday will
be a day where morning and afternoon temperatures for most
locations are nearly the same, with temperatures on Thursday
generally remaining in the 40s to low 50s due to cold air
advection and cloudy skies behind the front. Increasing northerly
winds can also be expected behind the front, with 15-25 MPH winds
inland and 20-30 MPH along the coast. Wind gusts may approach 40
MPH closer to the coast and wind Advisories will be needed (at
least) along the coast on Thursday.

Thursday night will be the coldest the region has experienced
this season, with overnight low temperatures forecast to fall into
the mid 20s to low 30s north of Interstate 10 and mid 30s to low
40s south. Drier air filtering in behind the front does look to
erode most of the clouds Thursday night, but GFS and NAM Bufr
soundings are continuing to advertise the potential for partly
cloudy skies with a persistent layer of moisture around 800-700
MB. These clouds would inhibit some of the overnight radiational
cooling and help keep temperatures warmer, affecting which
locations north of Interstate 10 would see a freeze on Friday
morning. For now, have kept temperatures fairly similar to the
previous forecast which advertises freezing temperatures along and
north of an Eagle Lake to Spring to Liberty line. Wind chills on
Friday morning are forecast to fall into the upper 10s to mid 20s
in many locations inland and coats will be needed when heading to
work or school.

Temperatures will warm into the mid 40s to low 50s on Friday as
skies continue to clear, with temperatures continuing to rebound
this weekend as surface high pressure departing the region and
onshore flow resuming allows highs to climb back into the upper
60s to low 70s by Sunday. Rain chances will increase Saturday
night through Sunday as moisture returns, with scattered showers
expected on Sunday as a cold front moves into the area. A brief
dry period is possible by the middle of next week before another
cold front reaches the region.

Huffman

MARINE...
Weak high pressure over the central plains will bring a light
north wind to the coastal waters this morning. As the high shifts
east, surface winds will veer to the east. A strong cold front
will push across the coastal waters late tonight and N-NE winds
will develop and strengthen significantly. Sustained winds in the
wake of the front will increases to 25 to 35 knots with higher
gusts. A Gale Watch has posted for the Gulf waters from 12z
Thursday through 06z Friday. SCA conditions will prevail over the
bays Thurs/Thurs Night.

There may be some impact on Thursday in the more north-to-south
ship channels as water is pushed out of the bays. The wind
direction is currently forecast to be north or even north-
northeast and am not expecting any low water advisories at this
time. However, will need to keep an eye out for any adverse
impacts if the wind direction changes more to more northwesterly.

Moderate onshore winds are expected to develop on Saturday and
near advisory conditions will be possible on Saturday night into
Sunday. The winds will diminish on Sunday night ahead of another
front early Monday. 43

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)      64  42  44  29  47 /  10  20  20  10   0
Houston (IAH)              67  48  49  33  49 /  10  40  20  10   0
Galveston (GLS)            66  53  54  41  51 /  10  50  30  10   0

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...Gale Watch from Thursday morning through Thursday evening 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...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...14
Aviation/Marine...43



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