Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 181133 AAA
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
533 AM CST Sat Nov 18 2017

.DISCUSSION...Updated for latest aviation discussion below.

&&

.AVIATION...Except for a few low cloud decks across the northern
ranchlands, mostly clear skies and light south-southeast winds
prevail across deep south Texas this morning. Expect VFR
conditions to prevail today as the 500mb ridge across northern
Mexico continues to provide subsidence across the region. MVFR
ceilings are expected to develop late this afternoon into this
evening as a strong cold front moves into the Rio Grande Valley
allowing moisture to pool along and ahead of the front. Breezy
north winds will develop in the wake of the front, mainly after
03z.

&&

.PREV DISCUSSION... /issued 346 AM CST Sat Nov 18 2017/

SHORT TERM (Today through Sunday): The latest surface analysis shows
a cold front across Oklahoma with a dry line extending into west
Texas. Water vapor imagery and satellite total Precipitable water
continues to indicate a dry air mass remains in place across much of
Texas courtesy of mid level ridging anchored over northern Mexico.
The cold front is forecast to move south across Texas today and
approach the northern ranchlands this evening. Ahead of the cold
front, a very warm day with above normal temperatures are expected
across deep south Texas today. High temperatures will be in the
upper 80s to around 90 degrees with a mix of sun and clouds. Near
record to record high temperatures are possible today.

The strong cold front is expected to move through deep south Texas
this evening. Despite the dry airmass, isolated to scattered showers
are possible along the front, especially across the coastal waters.
In the wake of the front, temperatures expected to quickly fall into
the 60s before midnight. Breezy north winds will persist overnight
with clearing skies. Low temperatures tonight will range from the
low 50s across the northern ranchlands to the lower 60s along the
beaches. Surface high pressure settles across the region on Sunday
resulting in diminishing northeast winds and below normal
temperatures. High temperatures on Sunday will be in the upper 60s
to lower 70s.

LONG TERM (Sunday Night through Friday): For the Sunday night
through Tuesday period, a broad upper trough will dig and spread
across the eastern half of the US. The forecast area will
generally remain on the backside of the trough. Onshore flow with
somewhat above normal moisture for this time of the year will
bring slight chances of showers to much of the eastern half of the
forecast area during the day on Monday. High temperatures on
Monday look to hover in the lower/mid 70s. For Tuesday, the
models push a cold front south into deep south TX somewhere in the
late afternoon/evening timeframe and this will have the net
effect of pushing low level moisture offshore and am expecting
little precipitation with the passage of the front. The ECMWF is
a little stronger with the front compared to the GFS, so have
split the difference in terms of wind speeds in the forecast. High
temperatures Tuesday afternoon ahead of the front will generally
rise into the upper 70s to mid 80s.

Wednesday through Friday looks dry across the region as modest
northwest-north flow prevails aloft with weak high pressure
at the surface. The GFS and ECMWF both maintain near to somewhat
above normal temperatures across the Rio Grande Valley during the
three-day time period, though the ECMWF is carrying somewhat
higher temperatures than the GFS. Will keep highs area-wide in the
lower/mid 70s for Wed/Thu with mid/upper 70s for Friday.

MARINE (Today through Sunday): Buoy 42045 (TGLO TABS Buoy K)
recently reported southwest winds around 17 knots gusting to
around 20 knots. Low pressure across north Texas will support a
tight pressure gradient along the lower Texas coast this morning.
Small craft should exercise caution on the Gulf waters this
morning due to elevated winds and seas. There will be some slight
improvement on Gulf waters this afternoon as the pressure gradient
relaxes. However, this will be short lived as the strong cold
front moves through the lower Texas coastal waters late this
evening and overnight bringing hazardous marine conditions. A Gale
Warning is in effect from 8 pm tonight through 9 am Sunday for
the Gulf waters 0- 60 NM east of Padre Island due to sustained
winds near Gale force and frequent Gale force gusts. A Small Craft
Advisory is in effect from 8 pm tonight to 9 am Sunday for the
Laguna Madre due to strong north winds.

Sunday night through Wednesday: The period will begin with
elevated wave heights with Small Craft Advisory conditions in
place, though seas will slowly subside Sunday night through
Monday. Surface high pressure will be in place across the waters
Monday night/Tuesday for modest winds/seas. Wave heights will be
on the increase again with freshening winds Tuesday night as a
cold front moves across the waters. Small Craft Advisory
conditions will redevelop Tuesday night and continue through
Wednesday.

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...Small Craft Advisory for winds from 8 PM this evening to 9 AM
     CST Sunday for GMZ130-132-135.

     Gale Warning from 8 PM this evening to 9 AM CST Sunday for
     GMZ150-155-170-175.

&&

$$

This product is also available on the web at:
HTTP://WEATHER.GOV/RGV

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