Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 221016
AFDBRO

Area Forecast Discussion
National Weather Service Brownsville TX
416 AM CST Wed Nov 22 2017

...Cold Front Currently Pushing Through South Texas...

.SHORT TERM (Today through Thursday): Sharp shortwave trough
axis along the Texas coast is beginning to make its right turn
into the Gulf waters. As this wave tracks east the cold front,
currently extending from south of Zapata to Aransas Pass to near
Galveston, should rapidly surge south through the RGV by or
shortly after sunrise. Isolated to scattered showers and
thunderstorms are noted ahead of the front over the Gulf coastal
waters but nothing is noted over land. Main large scale lifting
and main divergence region is over the NW Gulf with large scale
subsidence noted just behind the mid level trough. Not expecting
much in the way of rain or convection impacting inland areas but
did leave in slight chances across the the Lower Valley and
coastal region this morning along the sharp demarcation line
between the subsidence and frontal forcing.

Some patchy low clouds are forming along the front and model
soundings suggest low clouds to increase in wake of the front
as the cold advection increases. Models indicate clouds to stick
around through mid afternoon but believe sufficient mixing of very
dry air should allow for the lower clouds to break sooner.
Temperatures to fall through the morning before recovering this
afternoon with the sun breaking through. Winds increase
significantly through the morning as the pressure gradient
strengthens between surface high over the Southern Plains and a
develop low over the Central Gulf. Gusts 25 to 35 mph are possible
from the Mid Valley to the coast.

Winds quickly decouple this evening and with clear skies
temperatures plummet into the 40s for all areas except the
immediate coast where 50s should prevail.

Surface High pressure becomes centered over the CWA Thanksgiving
day making for a perfect day to gives thanks for. Clear and
chilly in the morning gives way to a sunny bright and cool to mild
day as highs range from the upper 60s to lower 70s. Can not ask
for anything better. Enjoy.


.LONG TERM (Thursday Night through Tuesday):

Long term begins with a very tranquil northwesterly flow across
the region. Surface high pressure will be in control for the most
part through the Thanksgiving/Black Friday weekend. At the
surface, as high pressure begins to settle east of our region,
surface winds will begin to transition to a southerly and
southeasterly direction, which will allow for an increase in low
level moisture. This should keep overnight lows slightly warmer
each night and daytimes highs will also inch slightly higher,
especially early next week as an upper level ridge pushes
eastward. Another frontal boundary will begin to enter the picture
toward midweek next week. In summary, mild/average temperatures
expected in the long term with a slightly above average expected
early next week.

&&

.MARINE:

(Now through Thursday): Pressure gradient to strengthen this
morning in wake of a cold front. 1030mb high over the Southern
Plains to combine with 1012mb low east of the coastal waters
producing strong surface winds today. Winds to increase quickly
behind the front that should be moving through the coastal waters
between 6-9am. Conditions appear favorable for frequent gale force
gusts as 35-40 knots winds at around 3000-4000 feet mix to the
surface. Gale warnings have been posted for the Gulf waters through
3 pm but could be trimmed back in areal coverage and time as the
main upper support quickly moves east. Seas should quickly respond
and should approach 10 feet in the outer waters. As winds begin to
diminish seas to lower but might take through the evening to drop
below 7 feet so Small craft advisories continue once the threat of
gales end.  High pressure settles over the RGV Thanksgiving day with
marine conditoins becoming very favorable by the afternoon.

(Thursday night through Tuesday): High pressure will be in control
for much of the period. With weak pressure gradient and lack of
swells, weather related marine hazards are not expected from late
Thanksgiving day through Sunday. Early next week the pressure
gradient will begin to tighten again between a strong low pressure
system develops over the central plains. This will likely cause at
least an uptick in winds and seas to round out this cycle.

&&

.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL  69  50  68  47 /  20   0   0   0
BROWNSVILLE          69  49  72  50 /  20   0   0   0
HARLINGEN            69  46  71  46 /  10   0   0   0
MCALLEN              71  47  73  48 /  10   0   0   0
RIO GRANDE CITY      70  43  74  45 /   0   0   0   0
SOUTH PADRE ISLAND   69  57  67  57 /  20   0   0   0

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...Small Craft Advisory for winds until 6 PM CST this evening for
     GMZ130-132-135.

     Small Craft Advisory from 3 PM this afternoon to midnight CST
     tonight for GMZ150-155-170-175.

     Gale Warning until 3 PM CST this afternoon for GMZ150-155-170-
     175.

&&

$$

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