Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 141746 AAB
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
1146 AM CST Tue Feb 14 2017

.DISCUSSION...Updated the forecast to reflect current trends in
the wake of a cold front moving offshore. The aviation discussion
follows.

&&

.AVIATION...High pressure will spread over the area tonight and
Wednesday. Still seeing MVFR ceilings at BRO and HRL, but expect
mixing out this afternoon, followed by VFR thereafter. Moderate
to breezy and gusty northwest winds will slowly decrease to light
tonight, strengthening to moderate again on Wednesday.

&&

.PREV DISCUSSION... /issued 529 AM CST Tue Feb 14 2017/

DISCUSSION...Updated for latest aviation discussion below.

AVIATION...Cold front progressing eastward this morning across
the western valley, with northwest winds 15g25kts in its wake. The
front should reach KMFE around 15z and KBRO around 18z. Shower
activity is forecast to increase along the front this morning, but
activity will be fairly light, as better dynamics for
thunderstorms remain off to the north. There will be a brief
period just before the front where winds shift more from the
southwest before the abrupt northwest winds shift arrives. Drier
air will filter in quickly behind the front this afternoon, with
quickly clearing skies. Skies will be CLR through the night with
north winds remaining 8 to 10kts.

PREV DISCUSSION... /issued 405 AM CST Tue Feb 14 2017/

SHORT TERM (Today through Wednesday):The long-expected front is
currently entering Zapata County from the northwest, being pushed by
the vigorous H5 low moving across Far West Texas. All models
pointing to a line of showers and with isolated thunder sweeping
across the region through the morning hours. Rainfall will not be
especially heavy, considering the lack of a fully saturated parcel
and earlier time frame of the frontal passage. Front should be
crossing Hidalgo County around 9 AM, and will reach Cameron County
between 11 AM and noon. Models show drier air quickly entering the
region from the west, so some latter afternoon heating is still
expected, as the cold pool is not expected to fully move into the
region until after sunset. Clear skies and cold air advection will
allow temperatures to falling to the upper 40s and lower 50s
areawide tonight. North winds around 10 knots will be continuing
through most of the day Wednesday, so daytime heating will be
tempered by continued cold air advection. This will hold high
temperatures below normal in the upper 60s.

LONG TERM (Wednesday Night through Monday):Models continue to
show decent consistency in the overall mid level split flow
pattern and the general weather trends. Above average
confidence in the forecast trends through Saturday then dropping
to slightly below average late in the weekend and early next week
with a large upper trough advancing across NW Mexico and Texas.

After a seasonal and continued dry Wednesday night and Thursday
we will continue to monitor a moderate strength mid level trough
expected to traverse the state Thursday night and Friday. Moisture
transport returns rather quickly with both GFS and ECMWF beginning
to indicate slight chance pops Thursday night. MAV/EC guidance
continue to indicate high pops Friday but will continue to cut
back some with deterministic output shows lower and inconsistent
moisture through the atmospheric column. Will also keep chance of
thunder near nil with trough axis moving to the east of the coast
by noon allowing for drier air to spread across the region.
Heights and thickness increase as shortwave ridge builds quickly
over the state as the mid level trough exits stage right. A warm
to hot and dry regime settles over the CWA for Saturday with upper
80s and lower 90 (our norm for winter 2017) cover much of the
region east of the coast. Next upstream mid level trough will
bring about some uncertainty with some timing and strength
differences. Forecast will not vary much from previous output with
rain chances creeping back into the region Sunday and moving
steadily east Monday. Temperatures do not show much drop with this
trough with its southern track and virtually no tap of Canadian
air.

MARINE: Now through Wednesday: Small Craft Advisories are in effect
for all marine zones, as gusty winds will be affecting the region
most of the day. This morning, southerly winds will be increasing
as the front approaches and the local gradient increases. The
initial wind shift will not include the strongest northerly surge,
so there will be a brief period early this afternoon when winds
will decrease to around 15 knots. The main surge of north winds
will arrive just after sunset, with winds increasing to 20 to 25
knots. Gusty north winds will continue through the night and into
Wednesday morning before gradually lowering.

The front will also bring a good chance for showers and isolated
thunderstorms this afternoon and evening. Be aware of localized
gusty winds and rougher seas.

Wednesday night through Saturday...High pressure builds over the
region and the Western Gulf Thursday and tracks east Friday. North
winds slacken quickly turning southeast Thursday and seas subside
steadily in response to the lowering wind. Next mid level storms
system moving into Texas Friday will allow for Southeast winds to
become moderate with a steady state moderate wind and sea regime
Saturday. Not expecting any small craft advisories or exercise
caution conditions at this time.

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...Small Craft Advisory until 6 AM CST Wednesday for GMZ150-155-170-
     175.

&&

$$

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