Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 270855

Area Forecast Discussion
National Weather Service Brownsville TX
355 AM CDT Tue Jul 27 2021

.SHORT TERM (Today through Wednesday): An inverted trough has
developed over the western Gulf of Mexico and is expected to move
across Deep South Texas today as it rotates around the base of the
mid level ridge. This disturbance will feed in slightly higher
PWATs, but they`re still rather unimpressive...generally 1.5 to 2.0
inches. This pattern will allow for a slight chance of isolated
showers and thunderstorms today and tomorrow as the upper level
support helps to aid diurnal forcing. Overall QPF should be low, but
some brief periods of heavy rainfall will be possible. Light to calm
winds combined with clear skies and elevated surface dew points both
early this morning and Wednesday morning will make patchy shallow
fog possible near sunrise across the ranchlands and portions of the
Rio Grande Valley. This fog will mix out quickly after sunrise.
Temperatures will be near normal or even a few degrees below in the
Rio Grande Valley today and Wednesday. Heat indices will reach the
100 to 106 degree range this afternoon and again on Wednesday.

.LONG TERM (Wednesday Night through Monday): Generally hot and dry
conditions will prevail through the period with broad 500mb
ridging anchored over the Rockies into the High Plains and surface
high pressure across the Gulf of Mexico. A slight chance of
showers and thunderstorms will be possible Wednesday night into
Friday as a series of weak mid level disturbances move west along
on the southern periphery of the ridge. High temperatures will be
near or slightly above normal Thursday and Friday due to the
slight increase of convection. Above normal temperatures are
expected for the weekend into early next week as rain chances
diminish. Heat index values across deep south each afternoon are
expected between 105 to 110 degrees. Heat advisory conditions will
also be possible across Starr and Zapata counties Friday into
early next week.


.MARINE (Today through Wednesday): Favorable marine conditions
are expected through Wednesday with a weak pressure gradient in
place. Wave heights will generally be 1 to 3 feet with light to
moderate southeasterly winds. An inverted trough will move into
the region today, increasing the chance for some isolated to
scattered showers and thunderstorms across the waters today and

Wednesday night through Saturday night...Very favorable marine
conditions will prevail along the lower Texas coast through much
of the period with high pressure in control. A weak pressure
gradient across the Gulf will maintain generally light onshore
winds and low seas. A slight up tick in winds and seas will be
possible very late in the period. Otherwise, no Exercise Caution
or Small Craft Advisory conditions are anticipated. Isolated
showers and thunderstorms are expected Wednesday night through
Friday and possibly a few over the weekend.


BAYVIEW/PORT ISABEL  90  77  90  77 /  20  10  20  10
BROWNSVILLE          93  77  93  77 /  20  10  20  10
HARLINGEN            93  76  92  75 /  20  10  20   0
MCALLEN              96  76  94  76 /  20  10  30   0
RIO GRANDE CITY     100  75  99  75 /  10   0  20  10
SOUTH PADRE ISLAND   85  80  85  80 /  20  10  10  10




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