Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 232347

Area Forecast Discussion
National Weather Service Brownsville TX
547 PM CST Thu Feb 23 2017

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


.AVIATION...Clear skies and southeast winds 10 to 15 knots will
continue through the nighttime hours. Elevated winds should
preclude fog formation. Winds will finally decrease just after
sunrise in response to the approach of the cold front. The front
will pass mid to late morning, with winds shifting to the NNW 10
to 15 knots. Winds will likely decrease quickly after frontal
passage, with 5 to 10 knot winds probably in the afternoon.


.PREV DISCUSSION... /issued 302 PM CST Thu Feb 23 2017/

SHORT TERM (Now through Friday night): 500mb ridging overhead and
high pressure off to the east continue to provide plenty of
subsidence with hot and dry conditions across Deep South Texas again
this afternoon. This is the third day in a row that BRO has tied or
set a new daily high temperature record. McAllen broke the daily
high temperature record and even set a record for the earliest 100-
degree day measured in a calendar year. Winds have shifted back to
the south/southeast and increased to just below Red Flag Warning
criteria when combined with very low RH values. South winds will
decrease overnight, but will remain moderate ahead of an approaching
cold front on Friday. Have added patchy fog for the eastern half of
the area as moisture recovers overnight and pools ahead of the front
prior to the wind shift.

Friday, the (very dry) cold front will move through in the afternoon
with winds veering to the north and eventually northeast late in the
evening. The main concerns will be the possibility of critical fire
weather after the front moves through and brings strong northwest
winds in its wake. Have posted a Fire Weather Watch for all of Deep
South Texas with exception to Coastal Cameron and Willacy.

LONG TERM (Saturday through Thursday): Little to talk about as
far as the upper levels go through the period with west-southwest
flow generally prevailing aloft over deep south TX as troughs go
by to our north Sunday then again on Tuesday. At the low levels:
for Saturday, easterly surface flow to prevail as a large area of
high pressure migrates eastward across north TX/OK into Arkansas.
Saturday`s high temperatures in the mid 70s coast/upper 70s to mid
80s inland will be roughly 7 to 13 degrees lower than record or
near- record high temperatures expected for Friday. For Sunday, a
surge of subtropical moisture moves northward across deep south TX
bringing increased clouds mainly in the morning, then southerly
flow through the day will bring higher max temps Sunday afternoon
than what will be seen on Saturday and will mostly range from the
lower 80s at the coast with mid/upper 80s inland.

Early Monday morning, a weak surface front will move through the
forecast area bringing a much drier low level northerly flow.
Downsloping effects will actually bring a warmer day on Monday than
Sunday, despite the passing cold front, with highs reaching the
lower 80s at the coast and mid 80s to around 90 inland. Onshore flow
quickly returns Monday night/Tuesday with rising heights/thicknesses
causing high temperatures to reach well above normal values running
12 to 18 degrees above normal Tuesday afternoon. Highs generally
look to reach into the mid 80s at the coast with upper 80s to mid
90s inland.

A stronger front is slated to move through deep south TX in the
Wednesday timeframe bringing increased clouds, low chances of
precipitation, and lower temperatures. If medium range model trends
continue, high temperatures should get bounced back down into the
80s region-wide on Wednesday. Chances of precipitation look to wind
down once again on Thursday as the front pushes well south of the
area. High temperatures on Thursday most likely will be drastically
lower behind the front compared to Wednesday, anywhere from 13 to 18
degrees lower, actually bringing temperatures down to below seasonal
norms, if only for a short time.

MARINE (Now through Friday night): South winds have increased
over the marine areas this afternoon with adverse conditions
possible at times. Winds will decrease slightly overnight with
seas remaining elevated at 3 to 5 feet. A brief lull in winds will
occur overnight ahead of an approaching cold front before
moderate northwest winds move across the area in its wake.

Saturday through Tuesday: Modest east surface flow on Saturday will
strengthen somewhat Saturday afternoon in response to a tightening
pressure gradient bringing Small Craft Should Exercise Caution
headlines to the waters. Small Craft Advisory headlines look to
develop/persist Saturday night through around midday Monday with
waves building to 5 to 7 feet and winds veering to southeasterly
early Sunday then southerly Sunday afternoon. A weak cold front will
move across the waters on Monday bringing modest and variable winds
through Monday night. Modest southeasterly onshore flow to set up
once again Tuesday. Small Craft Should Exercise Caution headlines to
prevail Monday afternoon through Tuesday as waves remain somewhat


TX...Fire Weather Watch Friday afternoon for TXZ248>255.



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