Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 061128
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
528 AM CST Tue Dec 6 2016

.AVIATION...
Satellite imagery shows low clouds exiting to the NE and feel this
trend will continue this morning leaving skies generally clear
across TAF sites through at least mid day. Could still get some
patch fog prior to sunrise and will need to watch trends. Models
not handling the clearing well as short term guidance is
suggesting IFR/MVFR cigs all day. The GFS seemed to initialize
best and leaned toward a NAM/GFS blend. A weak cold front over N
TX will move south today and weak lift behind the front will bring
lower ceilings back to SE TX with some patchy drizzle. MVFR/IFR
cigs expected to develop from north to south beginning around 21z
over KCLL/KUTS to around 00z at the Houston terminals and 03z near
KGLS. Winds will stay light for the next 24 hours but veer to the
north in the wake of the front. 43

&&

.PREV DISCUSSION... /ISSUED 411 AM CST Tue Dec 6 2016/

DISCUSSION...
Early morning split channel satellite imagery shows low clouds
persisting north of a College Station to Tomball to Winnie line,
with patchy fog having developed south of this line where skies
have cleared. Expect these low clouds to gradually lift later
this morning as isentropic upglide on the 295K surface associated
with yesterday`s surface low decreases. Radiational cooling where
clouds have thinned or cleared combined with recent rainfall the
region has received will result in additional fog development
through sunrise and continuing to monitor visibilities for a
possible Dense Fog Advisory later this morning. May see any fog
that develops persist mid to late morning (10-11 AM CST) as
forecast soundings indicate the morning inversion may be slow to
lift, delaying daytime mixing.

Surface analysis as of 06Z /12 AM CST/ showed a cold front
surging through the Texas Panhandle and this front will slide into
Southeast Texas later today, entering the region sometime early to
mid afternoon. NAM and GFS BUFR Soundings for College Station and
Lufkin both show enough low level saturation behind the front to
produce some patchy drizzle across the northern counties this
afternoon and eastern counties tonight. Otherwise, westerly winds
ahead of the front today will allow areas south of Interstate 10
to warm into the upper 60s to low 70s. Areas north of Interstate
10 look to rise into the upper 50s to mid 60s. Another cool night
is expected tonight with lows in the mid 40s to mid 50s.

Today`s front is expected to stall near the coast tonight,
lifting north as warm front during the day on Wednesday ahead of
the next (much stronger) cold front. A few showers will be
possible as the cold front approaches Wednesday afternoon, with
scattered showers developing along the front Wednesday night as
ascent associated with the front increases. This activity will
shift into the Gulf Thursday morning as the front clears the
region.

Strong cold air advection behind the front during the day on
Thursday will result in breezy to windy conditions across
Southeast Texas, with high temperatures only rising into the mid
40s to mid 50s. A Wind Advisory will likely be needed along the
Upper Texas coast and may be needed across the entire region with
north winds increasing into at least the 15 to 25 MPH range (with
stronger gusts). Winds will decrease overnight Thursday as a 1040
MB surface high builds into Texas.

Morning lows on Friday will be the coldest the region has seen
this season, with freezing temperatures extending as far south as
the Interstate 10 corridor. There is still some uncertainty on how
cold it will get on Friday morning. GFS and European MOS guidance
differ about 3-4 degrees on low temperatures across much of the
region, and this is a result of how they resolve clouds behind the
front. Soundings show a thin layer of moisture between 700-800 MB
persisting overnight Thursday behind the front (also evident in
some of the RH progs) that may inhibit some radiational heat loss
overnight. However, given the strength of the cold front am
inclined to side with moisture/clouds being scoured out and have
trended towards colder guidance. Freeze Warnings are expected
Friday morning, with temperatures below 32 degrees F for several
hours north of Interstate 10. Due to urban heat island effects,
the Houston metro may not quite reach freezing but will still be
cold with temperatures in the mid 30s.

Northerly winds and dry conditions will persist Friday into
Saturday, before surface high pressure sliding east of the region
allows for return flow by late Saturday. Low rain chances creep
back into the forecast Saturday and Sunday as moisture returns.
This returning moisture and warm air advection will allow
temperatures to dramatically rebound this weekend, with highs in
the mid 50s to low 60s on Saturday rising into the mid 60s to low
70s on Sunday. Rain chances will continue to increase late Sunday
into Monday as the next cold front moves into the region.

Huffman

MARINE...
West winds this morning will gradually veer to the north tonight
as a weak cold front over N TX slides south. A cold front will
move off the coast Wednesday night with strong cold air advection
and a tight pressure gradient helping to generate strong offshore
winds late Wednesday night into Thursday. Winds will gust to gale
force Thursday morning and a Gale Watch will likely be issued
later today. Strong winds will likely persist Thursday night into
early Friday. Winds will begin to veer to the east Friday night as
surface high pressure moves east of the region. Onshore winds will
strengthen Saturday and early Sunday as low pressure develops over
the Texas panhandle. Another cold front will cross the coast
Sunday night with a strong offshore flow redeveloping. 43

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)      62  46  63  41  45 /  10  10  20  40  10
Houston (IAH)              69  48  68  47  50 /   0   0  10  50  20
Galveston (GLS)            69  57  67  53  55 /   0   0  10  50  30

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION until 8 AM CST this morning
     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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