618
FXUS64 KBRO 170535 AAB
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
1235 AM CDT Tue Sep 17 2024

...New AVIATION...

.SHORT TERM...
(Tonight through Tuesday night)
Issued at 236 PM CDT Mon Sep 16 2024

Key Message:

-Rain chances will continue to pose a threat for localized areas of
minor flooding through the forecast period.

High pressure begins to build into Deep South Texas over the next
few days, however as this ridge builds we will continue to have some
weak impulses along with some leftover boundaries from activity
yesterday into this morning. This will be the focus of isolated to
scattered activity today, though we are not expecting as widespread
coverage today as we saw yesterday. This mornings KBRO sounding
indicated a PWAT of 2.50 inches which is near record for the day.
With precipitation chances generally between 40 and 60% across the
CWA this afternoon, we will continue to be at risk for heavy
rainfall with high rainfall rates which may lead to minor flooding
with any convection that develops. Areas of the Lower Valley who
received rainfall of 2 to 5 inches yesterday will be especially
susceptible to flooding and ponding of water on roads and low lying
areas. Drivers are urged to use precautions in any showers or
thunderstorms and water will rise rapidly on roadways with runoff
and the ground already being saturated.

Rain chances will taper off overnight, though some showers could
redevelop along the coast late tonight/early Tuesday morning. Rain
chances will once again increase late Tuesday morning into the
afternoon(30-40%). This activity will be more isolated in nature and
by the afternoon will be more driven by the sea breeze. Forecasted
PWATs will still be above normal, so the threat for brief heavy
rainfall with isolated minor flooding will continue in areas that
have received multiple rounds of rainfall in the previous days.

Temperatures overnight tonight and tomorrow will fall into the mid
70s to low 80s. Tomorrow high temperatures will be a bit warmer with
highs in the low 90s. Heat indices will will rise to between 105-110
degrees for much of the region.

&&

.LONG TERM...
(Wednesday through next Monday)
Issued at 236 PM CDT Mon Sep 16 2024

Global deterministic forecast models and ensembles continue to
depict a 591 dam heat dome/ridge building over northeastern Mexico
into Deep South Texas through the extended. This has been a trend
over the past week of models favoring ridging building over the
region. The synoptic and large-scale setup will favor slightly
warmer/hotter than normal temperatures during the long-term period
with mainly dry/rain-free conditions in place.

Atmospheric moisture content will be lower compared to previous
days/weeks with precipitable water (PWAT) values between 1.5-2.0
inches. However, it should be adequate enough to support a rogue or
isolated chance for a shower or thunderstorm nearly each day.
Subsidence, however, with the aforementioned mid-level ridging in
place, will help to keep things mostly suppressed during the period.
That said, expect for mainly dry or rain-free conditions to prevail
through the long-term period with an isolated chance for a shower or
storm nearly each day.

Temperature anomalies will run slightly warmer/hotter than mid-late
September standards through the extended. High temperatures are
expected to be in the mid to upper 90s for much of the region and
for much of the period. Moderate HeatRisk can be expected for the
most part through the extended. There could be areas of major
HeatRisk developing, especially in the Wednesday-Friday timeframe.
Heat indices are expected to range between 105-115F into
Saturday. That said, Special Weather Statements (SPS) to Heat
Advisories may be needed during the extended.

The weather pattern is progged to break down over the weekend, which
will allow for temperatures (the warmth) to relax some.

&&

.AVIATION...
(06Z TAFS)
Issued at 1228 AM CDT Tue Sep 17 2024

VFR conditions are expected to persist through the TAF cycle at
all TAF sites. Light southeasterly winds should continue as well.
Some low-level clouds are expected to be in the region, thus skies
are expected to range from mostly sunny to partly cloudy. Isolated
showers and thunderstorms are possible during the afternoon hours,
but confidence was not high enough to include in the TAF package.

&&

.MARINE...
Issued at 236 PM CDT Mon Sep 16 2024

Now through Tuesday Night...Generally favorable marine conditions
will prevail with light winds and seas around 1 foot. Chances of
showers and thunderstorms will continue at times through the
forecast period that could lead to locally enhanced winds and
seas.

Wednesday through Monday....Outside of any convection, favorable
marine conditions (light to moderate winds and light seas) are
expected to prevail Wednesday through next Monday.

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             90  78  94  80 /  50  10  30  10
HARLINGEN               91  76  95  77 /  50   0  30   0
MCALLEN                 95  78  99  80 /  50   0  20   0
RIO GRANDE CITY         92  76  96  78 /  40  10  10   0
SOUTH PADRE ISLAND      87  82  90  82 /  30  20  20  20
BAYVIEW/PORT ISABEL     89  78  92  78 /  40  10  20  10

&&

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

$$

SHORT TERM...68-McGinnis
LONG TERM....23-Evbuoma
AVIATION...64-Katz