Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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077
FXUS64 KHGX 292335
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
535 PM CST Tue Nov 29 2016

.AVIATION...
For most sites, dry air on northwest flow should keep fog from
being an issue tonight. However, with a boundary stalled just
inland of the Gulf shore, this seems unlikely at GLS, which
should see some fog develop before gusty northwest winds on a cold
front blast dry air in. Went with MVFR conditions now, on chance
that stalled boundary drifts southward this evening, but potential
for IFR definitely exists and may be cause for later amendments.

Other challenge will be how and when winds get gusty as cold front
works through. In collaboration with the CWSU, agree on bringing
in gustier winds a little after winds just off the surface
increase. Along with that, the narrow band of clouds near the
coast should also depart the area.

&&

.PREV DISCUSSION... /ISSUED 408 PM CST Tue Nov 29 2016/

DISCUSSION...
The frontal boundary responsible for thunderstorms across parts
of the Brazos Valley and Piney Woods earlier this morning as it
lifted north is now sagging south across the region this
afternoon. Surface analysis shows this boundary snaked from Edna
to Katy to Dayton, with satellite imagery showing enhanced cumulus
developing along the boundary. Despite this, convection this
afternoon has been largely limited as warm air advection at 850
and 700 MB has resulted in a strengthening cap across the Houston
metro. Low level warm air advection today has also resulted in a
few locations reaching or setting record high temperatures, with
Houston Intercontinental having reached at least 84 degrees as of
4 PM (which would exceed the record of 83 set in 2006).

Cannot rule out a few showers developing underneath this cap as
the boundary slowly sags towards the coast this afternoon, with
scattered showers and thunderstorms blossoming over the coastal
waters and extreme southeastern counties this evening as a
secondary cold front across North and Central Texas sweeps off the
coast this evening and tonight. May see a few of the storms across
the coastal waters become strong to marginally severe, but this
activity will continue to move into the northern Gulf and away
from the Upper Texas coast with the associated front. Until the
cold front moves off the coast tonight and ushers in drier air,
may see some patchy fog across the bays and nearshore waters with
warm, moist air pooled right along the coast. Otherwise, expect
overnight lows in the low 40s to mid 50s.

Surface high pressure building into the region in the wake of
tonight`s front will result in dry, cooler weather for the region
on Wednesday and Thursday. Elevated north winds (15-20 MPH) and
relative humidity values falling to near 25 percent during the
afternoon tomorrow will result in elevated fire weather conditions
for most inland areas tomorrow afternoon, but decreasing winds on
Thursday will help limit overall fire weather concerns. Expect
highs Wednesday and Thursday to be in the 60s with lows ranging
from the upper 30s across the extreme northern counties to mid 50s
along the coast.

Attention then turns to the upcoming weekend as energy from an
upper trough approaching from the west cuts off over northern
Mexico. Surface high pressure shifting into the southeastern US on
Friday will allow moisture to begin surging into the region, aided
by the development of a coastal trough along the Middle Texas
coast. Southwest flow aloft combined with enhanced low level
convergence from the coastal trough will result in periods of
showers and thunderstorms across Southeast Texas in the Saturday
through Monday timeframe. With precipitable water values climbing
to near 1.7 inches along the coast, have increasing concerns for
heavy rain to impact parts of the Upper Texas coast. Medium range
guidance has come into better agreement on the overall upper
pattern evolution, but still offers different timing on when the
upper low will lift across Texas and placements on the coastal
trough that develops (which would affect which areas see the
heaviest rain). Regardless, this weekend looks cool, wet, and one
to watch for heavy rain impacting parts of the Upper Texas coast.

Huffman

MARINE...
As a dry cool front nears the coastline latter this afternoon
..recent stout onshore winds will begin to weaken and veer more
southwesterly ahead of this feature. The offshore passage of this
weak boundary...followed by a more distinct cold front...will
drive northerlies back up to nearshore caution to offshore
advisory levels tomorrow morning. Offshore flow weakens and backs
more east Thursday as a late week coastal trough begins to take
shape. After a brief respite Friday...a persistent Friday and
Saturday easterly fetch will push a far offshore building swell
into our waters. Couple this moderate easterly fetch/high swell
with a high probability of precipitation makes for hazardous
boating conditions over the weekend. The northeast lift and
eventual exit of a coastal surface low Monday-Tuesday will mark
the end to a string of unfavorable days on the local waters. 31

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)      46  65  40  66  45 /   0   0   0   0   0
Houston (IAH)              52  67  42  67  46 /  10   0   0   0   0
Galveston (GLS)            60  68  54  65  58 /  30   0   0   0   0

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...High Rip Current Risk until 6 PM CST this evening for the
     following zones: Brazoria...Chambers...Galveston...
     Matagorda.

GM...SMALL CRAFT SHOULD EXERCISE CAUTION Wednesday 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...Matagorda Bay.

     Small Craft Advisory until 8 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.

     Small Craft Advisory from 6 AM to noon CST Wednesday 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.

&&

$$

Aviation/Marine...25



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