Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 281137 AAA
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
637 AM CDT Fri Apr 28 2017

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

&&

.AVIATION...Latest satellite imagery and surface observations
indicates some low clouds decks and patchy haze/light fog across
the area. VFR conditions expected through early this evening. Will
mention TEMPO MVFR conditions now through 14z. Brownsville VAD
winds shows winds near 40 knots at 2000 feet and will continue
LLWS at all taf sites through 14z. Moderate to breezy winds will
develop later this morning...and will increase even further to
windy levels by this afternoon. MVFR ceilings return to the area
after sunset with gusty southeast winds continuing overnight.

&&

.PREV DISCUSSION... /issued 414 AM CDT Fri Apr 28 2017/

SHORT TERM (Now through Saturday): A mix of low and high level
clouds prevail across the region this morning. Both the NAM/GFS
shows a pocket of dry air between 925 to 850 mb streaming north
along the coast. This has allowed for a decrease in low clouds
across the eastern portions of area overnight. Brownsville VAD
wind profile indicates winds around 50 knots at 2000 feet.

Broad 500mb trough across the country will deepen across the western
United States today through Saturday. The pressure gradient will
tighten today as surface low pressure across northwest Texas
interacts with high pressure across the eastern Gulf of Mexico. This
will result in breezy to windy conditions across Deep South Texas
for today. A wind Advisory is now in effect for Cameron, Willacy and
Kenedy counties from 11 am to 6 pm. Winds will remain fairly light
across the far western portions of the area today as a surface
trough/dryline moves into west central Texas this afternoon. Well
above normal temperatures today and Saturday with dewpoints in the
lower 70s across the coastal sections, with support heat index
indices in the 105 to 109 degree range across the eastern portions
of the CWA each afternoon. No rain is expected through the short
term due to the very limited low to mid level moisture across the
region.

LONG TERM (Saturday Night through Thursday): Models remain in
good agreement with the established longwave trough pattern across
the Western two-thirds of the U.S. A strong upper jet on the
western side of the trough dives southeast into the base of the
trough closing off a mid level low over the Southern Rockies
Saturday. This low makes its way steadily east moving across the
Texas Panhandle and into the Central Plains Sunday. This will push
a vigorous cold front through Deep south Texas Saturday
night/early Sunday. Zonal flow becomes established across South
Texas Monday through Wednesday than model consensus continues to
trend with an increasing amplified flow the middle of next week
surging another significant cold front through the region at the
end of the forecast period.

The first cold front moves into the northern Ranch lands after
midnight Saturday night and moves rather quickly southward on the
heels of a 35-45 knot low level northerly flow. Brief strong and
gusty winds should mark the arrival of the front but not
expecting much in the way of rainfall. Frontal forcing looks
impressive but moisture remains very limited for the majority of
the CWA with exception to the Northeast third and the coastal
waters. Have maintained slight chances along the coastal counties
at this time. Drier and cooler air, as much as 15 degrees drop, is
expected for Sunday and up to 20 degrees for Monday morning. As
for fire weather concerns...Latest guidance indicates the
strongest winds in the morning with the pressure gradient
weakening through the afternoon. This does not match up well as
lowest relative humidity reading will occur during the afternoon
hours when winds are diminishing. In any case, elevated fire
danger is approached for a few hour over Western areas but
confidence for a Fire Weather Watch at this time. Later shifts
will need to monitor for timing differences in peak winds.

Monday through Wednesday the zonal flow aloft will maintain a dry
and seasonal period with the extreme temperatures of late taking
a break. Temperatures guidance shows near to slightly above normal
temperatures as does the going forecast. Strong mid level ridge
develops over the West the middle of the week with a strong
shortwave trough diving through the Rockies Wednesday. This will
drive another cold front through our region by Thursday morning
bringing with it a chance of showers and thunderstorms and
dropping temperatures once again.

MARINE:(Now through Saturday): Buoy 42020 reported south winds
around 16 knots with gusts near 19 knots and seas of 4.3 feet with a
period of 7 seconds at 03 CST/08 UTC. Moderate south winds now will
steadily strengthen and become strong later this morning. A Small
Craft Advisory is now in effect for the Laguna Madre from 9 am
through 7 pm this evening. Additional Small Craft Advisories will
likely be needed on the Laguna Madre on Saturday. A Small Craft
Advisory is also in effect for the Lower Texas Gulf waters beginning
at 9 am through Saturday afternoon due to strong winds and building
seas. Low pressure across northwest Texas interacting with high
pressure across the eastern Gulf of Mexico will maintain adverse
marine conditions along the Lower Texas coast through the forecast
period.

Saturday night through Tuesday...Main feature this period will be
a strong cold front surging through the coastal waters prior to
sunrise Sunday. Adverse marine conditions will already be
occurring in advance of the front due to a strong southerly flow.
Winds abruptly shift to the north Sunday morning with some gusts
approaching gale force. Strong north winds and rough seas continue
through the first half of the day with winds slowly diminishing
later in the afternoon while seas taking longer to subside. Much
improved conditions are expected Monday and Tuesday as high
pressure spreads over the Gulf with light to moderate southeast
winds returning.

&&

.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL  95  80  93  71 /  10  10  10  10
BROWNSVILLE          95  79  96  72 /  10  10  10  10
HARLINGEN            96  78 100  69 /  10  10  10  10
MCALLEN             101  78 102  69 /  10  10   0  10
RIO GRANDE CITY     106  77 106  67 /  10  10   0   0
SOUTH PADRE ISLAND   89  80  86  73 /  10  10  10  10

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...Wind Advisory from 11 AM this morning to 6 PM CDT this evening
     for TXZ251-254>257.

GM...Small Craft Advisory for winds until 7 PM CDT this evening for
     GMZ130-132-135.

     Small Craft Advisory until 7 PM CDT Saturday for GMZ150-155-170-
     175.

&&

$$

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

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