Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 301132 AAA
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
632 AM CDT Fri Jul 30 2021

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

&&

.AVIATION...Light and variable winds with mostly clear skies
prevail across deep south Texas early this morning. The
combination of a weak surface trough, abundant moisture and the
sea breeze will support some convection during the late morning
into the afternoon. Brief MVFR conditions will be possible in and
around any convection. Otherwise, expect VFR conditions and
generally light winds across the Rio Grande Valley for the next 24
hours.


&&

.PREV DISCUSSION... /issued 420 AM CDT Fri Jul 30 2021/

SHORT TERM (Now through Saturday): The center of a 500mb ridge will
remain parked over the Kansas and Oklahoma through much of the
period. At the surface, broad high pressure will prevail across the
Gulf of Mexico with some weak coastal convergence/troughing along
the extreme Northwest Coast of Mexico and into the CWA. Also, deeper
tropical moisture is expected to increase along the lower Texas
coast today. BRO sounding from last night shows a precipitable water
of 2.08 inches. The combination of abundant moisture, a weak surface
convergence and the seabreeze will lead to isolated to scattered
showers and thunderstorms later this morning into the afternoon. The
elevated PWAT could support locally heavy rain amounts at times.
Another round of isolated to scattered seabreeze convection is
expected on Saturday.

Also, mostly clear skies, very light winds and elevated dew points
may allow some patchy shallow fog to develop around sunrise across
the ranchlands and portions of the Rio Grande Valley this morning.
Any fog that forms will be short lived and is expected to mix out
fairly quickly after sunrise.

High temperatures today and Saturday will be near to slightly below
normal and highly dependent on the timing of any convection. Very
warm temperatures and high dewpoints will lead to heat indices in
the 105 to 110 degree range across much of the CWA this afternoon
and again on Saturday. The heat index may briefly exceed a 110
degrees across Zapata and Starr Counties Saturday afternoon.

LONG TERM (Saturday Night through Thursday): Although dry weather
is forecast for the first half of the period, isolated showers and
thunderstorms may return for Tuesday through Thursday as 500 mb
troughiness deepens over the eastern United States and northern
Gulf Coast. The initial dry weather and subsequent slight chance
of precipitation will assist in allowing temperatures to hold at
near to above normal levels.

MARINE (Now through Saturday): Favorable marine conditions are
expected through the period with a weak pressure gradient in place.
Wave heights will generally be 2 feet or less with light to
occasionally moderate southeasterly winds. Isolated to scattered
showers and thunderstorms are forecast today and again late tonight
into Saturday which could lead to brief periods of elevated seas and
increased winds.

Saturday Night through Thursday: Light to moderate winds and low
to moderate seas will prevail along the Lower Texas Coast due to
high pressure over the western Gulf of Mexico. However, winds may
be strong enough over portions of the lower Texas coastal waters,
especially the Laguna Madre, to warrant Small Craft Exercise
Caution.

&&

.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL  91  79  92  79 /  30   0  20   0
BROWNSVILLE          93  78  94  79 /  30  10  20   0
HARLINGEN            93  77  94  78 /  30   0  20   0
MCALLEN              95  78  97  78 /  20   0  20   0
RIO GRANDE CITY     100  77 102  78 /  20   0  20   0
SOUTH PADRE ISLAND   87  82  87  81 /  20  10  20   0

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...None.
&&

$$

This product is also available on the web at:
https://weather.gov/rgv

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