Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 062359 AAA
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service BROWNSVILLE TX
559 PM CST Tue Dec 6 2016

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

&&

.AVIATION...Mostly clear skies and light winds prevail across Deep
South Texas this evening. Expect VFR conditions to continue this
evening before a weak cold front moves into the area tonight.
MVFR to IFR conditions will develop late tonight as low clouds/fog
develops across the Rio Grande valley and northern ranchlands as
winds become light and variable. Ceilings will lift slightly by
mid to late morning but MVFR ceilings expected across much of the
area through Wednesday afternoon.

&&

.PREV DISCUSSION... /issued 323 PM CST Tue Dec 6 2016/

SHORT TERM (Tonight through Wednesday Night):A nearly zonal flow
across the southern half of the country this afternoon will allow
a cold front to move into the CWA tonight before stalling. This
will allow patchy fog to develop across portions of the Rio Grande
valley and northern ranchlands late tonight into early Wednesday
morning. A slight chance of light rain will develop across the
coastal sections of the CWA Wednesday afternoon into Wednesday
evening and rain chances will increase Wed night as a stronger
cold front approaches deep south TX late Wed night.

LONG TERM (Thursday through Tuesday): The first major cold front
of the winter season will arrive early on Thursday and quickly
move through the RGV during the morning and early afternoon hours.
A non-diurnal temperature trend will happen as highs will
actually occur around midnight Thursday. Readings will hold steady
initially before falling quickly through the remainder of the
day. By late afternoon readings across the CWA will be in the mid
40s to mid 50s. Rainfall will accompany the frontal passage
however amounts will be limited given and initial dry/cool air
surge the day before.

A strong surface high pressure system...around 1040mb...will
filter into North TX...with an increasing pressure gradient
bringing strong 30 to 40 knot winds near the coast and over the
offshore waters. The Gale Watch remains in effect over the Gulf
Waters for 6am Thursday through at least Midnight Friday.

The high pressure will funnel cold arctic air into the Valley
with temperatures falling in the mid to upper 30s across the
Northern Plains to mid to upper 40s across the Lower RGV. Winds
will be begin lessening by Friday...but with it still being rather
breezy...wind chill values or what it will feel like...will be in
the 30s and 40s. Meanwhile...weak coastal troughing will keep
light precip in the forecast...mainly along the coastal areas and
water through Saturday.

The high pressure will settle briefly over the Southern Plains
before quickly moving east as the next storm system moves into
the Northern CONUS. This will allow for onshore flow to return and
temperatures will modify through the weekend...with Sunday being
the warmest day in the period.

Another quick moving but less strong cold front is forecast to
move into the area Sunday night into Monday. Rain chances will be
limited...however another small cool down is expected.

MARINE:

Tonight through Wednesday night: Seas were near 3 feet with
southwest winds near 16 knots at buoy020 this afternoon. Winds
will shift to the northeast across the coastal waters tonight as
cold front moves offshore the lower Texas coast. Light northeast
winds tonight will be light and variable Wednesday as the front
stalls across the northwest Gulf of Mexico. Winds will be from the
east Wed night before a stronger cold front moves through the
coastal waters Thurs morning.

Thursday through Sunday: Gale force winds are expected to develop
on Thursday as a strong cold front moves through the offshore
waters. Strong north winds in excess of 30 Knots...with gusts to
40 Knots will create hazardous marine conditions. Seas will
quickly rise in response...with waves heights increasing to over
10 feet. Strong surface high pressure will follow the cold front
will winds and seas remaining elevated into Friday...before
bringing to fall. However...moderate winds and moderate seas will
continue through the weekend as a tight surface pressure gradient
keeps near Small Craft Advisory conditions over the waters.

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...Gale Watch from Thursday morning through Thursday evening for
     GMZ150-155-170-175.

&&

$$

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

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