Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 102332 AAA

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
632 PM CDT Mon Aug 10 2020

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

.AVIATION...Satellite and radar images as well as surface
observations indicate isolated convection offshore the extreme
northeast Mexican coast early this evening. Otherwise...some mid
level clouds were across the CWA. Expect VFR conditions to prevail
across the Rio Grande Valley tonight into early Tues morning as
the 500mb subtropical ridge across west Texas continues to provide
subsidence across south Texas.

.PREV DISCUSSION... /issued 248 PM CDT Mon Aug 10 2020/
SHORT TERM (Tonight through Tuesday Night): 500 mb high pressure
over Texas will continue to dominate in the short term. Increased
PWATs with the 12z sounding coupled with light SE winds and
moderate mid to low level moisture will keep a chance of sea
breeze showers and thunderstorms, mainly across the coastal
counties, for the remainder of the afternoon. As the ridge
continues to build into Tuesday subsidence should lead to a slight
drying of the atmosphere marginally lowering PoPs for the
remainder of the short term, though isolated sea breeze showers
and thunderstorms can not be ruled out. Temperatures should remain
near normal with heat indices of 104 to 108 across much of the

LONG TERM (Wednesday through Monday): The latter half of the
workweek will feature hotter conditions as afternoon temperatures
tick upward slightly with the influence of a strengthening 500 mb
ridge centered over West Texas and the Desert Southwest. Elected
to trend slightly warmer than the model blend and more in line
with the MOS guidance in regards to the high temperatures. The
heat indices should range between 105 and 110 degrees each
afternoon. The rain chances are expected to be generally low as
moisture will be limited, however, will keep a silent 10 POP for
any brief stray shower activity along a weak sea breeze during
Wednesday and Thursday. A slightly better chance for a sea breeze
shower or thunderstorm may be possible Friday. Warm and muggy
conditions overnight will remain typical for the middle of August.

Rain chances increase this upcoming weekend and into the start of
next week as an inverted mid-level trough is modeled to advance
towards the region before eventually pushing inland across Mexico.
With the increased moisture and cloud cover, the afternoon high
temperatures are expected to back off slightly compared to the
conditions for late this week as highlighted in the previous
paragraph. The overnight conditions will remain warm and sticky.

MARINE (Now through Tuesday night): Favorable conditions should
continue as high pressure continues to build in the area. Light
onshore winds and slights seas will continue. Isolated showers
and thunderstorms will still be possible through the timeframe,
which could increase seas slightly.

Wednesday through Saturday night: Surface high pressure that
extends across the Gulf of Mexico will continue to lead to a
modest pressure gradient and fair marine conditions. Light to
moderate onshore winds and low to moderate seas continue to
prevail. Shower and thunderstorm activity will be expected to
increase this weekend thanks to the approach of a mid-level
inverted trough.

BAYVIEW/PORT ISABEL  80  92  80  93 /  10  20  10  10
BROWNSVILLE          79  95  81  95 /  10  20  10  10
HARLINGEN            78  95  79  97 /  10  20  10  10
MCALLEN              79  98  79  99 /  10  20  10   0
RIO GRANDE CITY      78 101  78 102 /  10  10  10   0
SOUTH PADRE ISLAND   82  88  83  88 /  10  10  10  10



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