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743
FXUS64 KBRO 220433 AAA
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
1133 PM CDT Sat Sep 21 2024

...New AVIATION...

.SHORT TERM...
(Tonight through Sunday night)
Issued at 217 PM CDT Sat Sep 21 2024

A strong mid-level ridge will continue to be over Texas and
Northern Mexico through tonight. However, the ridge will then be
flattened and slowly drift off towards the east. Meanwhile on the
surface, the onshore flow is expected to continue so that plenty
of low-level moisture, which will keep the heat indices around
105. However, the actual high temperatures for tomorrow are
expected to be in the 90s. WPC`s experimental heat risk shows
mostly minor heat risk for tomorrow, with a few pockets of
moderate risk. As for the low temperatures, the lows are expected
to be generally in the 70s.

Weak sea breeze activity along with differential heating could
allow for some showers and thunderstorms to develop in the
afternoons. However, more drier air is expected to move into the
region. PWAT values are expected to decrease from 1.8 inches to
about 1.35 inches over the course of the short term forecast
period. While, the drier air should hinder the development of
showers and thunderstorms, the most likely areas for showers and
thunderstorms to develop will be near the coast.

The rip current risk is expected to remain low through the short
term forecast period and no other coastal hazards are currently
expected either.

&&

.LONG TERM...
(Monday through next Saturday)
Issued at 217 PM CDT Sat Sep 21 2024

A shallow, undulating H5 wave pattern will stretch across the
southern CONUS at the beginning of the long term. Deep South Texas
and the Gulf of Mexico will see mainly seasonal but nonetheless
somewhat unsettled weather. Convection over the Gulf will be a
staple, but daytime sea breezes will feed off ample available
moisture and will spread over the CWA with isolated to scattered
showers and tstorms Monday through Thursday. Brief heavy rainfall
will be possible, with a threat of mainly isolated nuisance type
flooding. We forecast modest overall rain amounts below flash
flood guidance through Thursday.

A mid-level low may drop south from the Southern Plains into
North Texas Tuesday into Wednesday, triggering stronger weather
there initially. By Thursday, the system will start to pull drier
air toward the COunty Warning Area from upstream which will tend
to cut off or counteract early to midweek convection. The models
tend to back away from quite as much overland precipitation by
next Friday and Saturday.

Through the long term, temperatures will trend slightly above
normal with a good mix of clouds and sun and light to moderate
winds. By Wednesday (the best day for rain) east to southeast
winds will start to back to north and northeast as they will be
influenced by low pressure to the north instead of Gulf high
pressure. Some drying will occur on Thursday, followed be fewer
clouds next Friday and Saturday as the drying continues.

The picture could be complicated a bit by a disturbance
developing in the Caribbean and moving north into the Gulf around
mid-week (see the marine discussion below). There is still a lot
of uncertainty associated with the system, but the NHC is
forecasting a medium (60%) chance of tropical cyclone formation
in the next 7 days. Long range models show one solution where the
mid-level low and the potential tropical system eventually merge
and interact over the lower Mississippi Valley next weekend.

&&

.AVIATION...
-- Changed Discussion --
(06Z TAFS)
Issued at 1129 PM CDT Sat Sep 21 2024

VFR is anticipated at the aerodromes through the next 24 hours.
Light to moderate winds and clear to partly cloudy skies will
occur with precipitation not expected.
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&&

.MARINE...
Issued at 217 PM CDT Sat Sep 21 2024

Tonight through Sunday Night...Mostly favorable conditions are
expected to persist through the Sunday night. Light to moderate
onshore flow with seas mostly between 1 to 2 feet with a few 3
foot waves possible. Isolated showers and thunderstorms are
possible and could result in locally elevated winds and seas.

Monday through Thursday night...we expect light to moderate winds
and low to moderate seas through Wednesday. East to southeast
winds will back to north and northeast on Wednesday and will
subsequently become moderate to fresh over the Gulf on Thursday.
Small craft should exercise caution to marginal small craft
advisory conditions will be possible on Thursday and Thursday
night, mainly from higher seas, and could extend through
Saturday. Isolated to scattered showers and thunderstorms will
develop from time to time through the entire marine forecast.

High pressure will dominate over the Gulf into the early part of
the week. A broad area of low pressure is likely to form by the
early to middle part of next week over the Northwest Caribbean
Sea and the adjacent portions of Central America. Gradual
development of the system will be possible, and a tropical
depression could form as the system moves slowly to the north or
northwest over the northwestern Caribbean Sea and across the Gulf
of Mexico through the end of next week. There is a medium chance
(60%) of tropical cyclone formation in the next seven days.
Regardless of development, winds and seas will start increasing
across the Southeast Gulf early next week.

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             78  91  76  91 /   0  10  10  40
HARLINGEN               75  93  74  92 /   0   0   0  40
MCALLEN                 78  96  76  96 /   0  10   0  30
RIO GRANDE CITY         77  94  74  94 /   0  10   0  20
SOUTH PADRE ISLAND      82  88  81  87 /   0   0  10  40
BAYVIEW/PORT ISABEL     77  90  76  89 /   0   0  10  40

&&

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

$$