326
FXUS64 KBRO 041128 AAA
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
628 AM CDT Fri Apr 4 2025

...New AVIATION...

.SHORT TERM...
(Today through Saturday)
Issued at 340 AM CDT Fri Apr 4 2025

Key Messages:

* Unseasonably warm and windy conditions are expected to continue
  through today; still warm but not windy on Saturday.

* There is a moderate Heat Risk for much of the region today; peak
  heat indices are expected to range between 100-108F degrees.

* Strong south-southeast winds 25-35 mph gusting up to 50 mph has
  resulted in a Wind Advisory for the eastern counties today.

* Multiple marine hazards are in effect through this weekend due to
  the strong winds.

Multiple hazards remain in effect for parts of Deep South Texas and
the Rio Grande Valley due to a continuation of strong south-
southeast winds. These breezy to windy conditions are a byproduct of
an enhanced pressure gradient over the region (with some local
geographic enhancements) due to an anomalously strong 550 mb trough
over the Rockies bumping up against an anomalously strong 592 mb
ridge off the Southeastern U.S. Coast. In fact, a baroclinic zone
and elongated frontal boundary has been established from the
southern Plains to Mid-Atlantic Region, which has been driving an
active weather pattern including rounds of severe thunderstorms and
flooding rains across parts of the central and southern U.S.

With this enhanced pressure gradient in place coupled with the local
geographical enhancements, the "Wind Valley Machine" will continue
through today as we`re expecting strong south-southeast winds 25-35
mph to gusts up to 50 mph today and possibly into this evening. Our
eastern counties are favored to see these winds today. As such, a
Wind Advisory has been hoisted from 9am-9pm today for Inland and
Coastal Kenedy, Willacy, and Cameron Counties, and southern Hidalgo
County.

VAD wind profiles this morning shows winds at about 3,000 feet AGL
of 34 m/s or 76 mph. With BUFKIT soundings showing the capping
inversion (seen on our KBRO 00z sounding) weakening this morning and
mixing heights increasing as high 900 mb, it`s possible that we can
see some of these winds mix down to the sfc later today. Finally,
models are also showing a more robust wind field compared to last
night (spatially and magnitude-wise) with sampled 850 mb low level
jet (LLJ) winds ranging between 45-50 kts. The NAEFS are suggesting
500mb, 850mb, and near sfc v-vector winds on the order of +1 to +2
STDEVs above normal. That said, wouldn`t be surprised to see some
isolated gusts of greater than 50 mph today.

Ahead of an approaching cold front, today will also feature another
unseasonably warm day. Increasing sfc based differential heating due
to clearing skies coupled with strong southerly winds yielding
increased moisture and warm air advection (WAA), daytime highs will
easily climb into the 90s across much of Deep South Texas and the
Rio Grande Valley with a couple of 100s possible far west across
Zapata and western Starr Counties. These values (anomalies) are on
the order of 5-10 degrees warmer than normal for early April
standards. With dewpoint (Td) temperatures in the 70s, heat indices
are expected to range between 100-108F degrees later this afternoon
along the Rio Grande Valley (Cameron, Hidalgo, Starr, and Willacy
Counties) and parts of the Northern Ranchlands (ie Brooks and Kenedy
Counties). Due to the combined effects of high humidity values and
very warm temperatures, a moderate (Level 2) Heat Risk is
anticipated for much of Deep South Texas and the Rio Grande Valley
with a pocket of major (Level 3) Heat Risk for parts of Mid-Valley
into the Lower Valley today.

Tonight will feature warm and muggy conditions. Low level clouds
will be on the increase again due to copious amounts of low level
moisture from recent rains trapped underneath another possibly
capping inversion and marine layer influences. Winds may linger and
so it could still be quite breezy especially early on. Overnight
lows are expected to hold in the 70s across the region.

Saturday will be our last day of unseasonable warmth before a cold
fropa brings a welcome airmass change of drier and unseasonably
cooler conditions into the region Sunday into early next week. A pre-
frontal trough will shift winds from the south to out of the north
on Saturday before the colder air arrives with the cold front late
Saturday. High temperatures will have the chance to climb into the
upper 80s northwest to lower 90s most other places under partly
cloudy skies. 80s are expected along the beach due to onshore
flow/influences.

&&

.LONG TERM...
(Saturday Night through Thursday)
Issued at 340 AM CDT Fri Apr 4 2025

The most significant event during this portion of the total
forecast will be temperatures. The passage of a cold front through
the BRO CWFA is anticipated for the daylight hours of Saturday.
Unseasonably cool low temperatures are forecast for the morning
hours of Sunday through Wednesday, with values ranging in the
upper 40s to mid 50s throughout this period. In addition to
providing a refreshing break to the early Spring swelter, these
temperatures may help in briefly nullifying the horde of
mosquitoes terrorizing Deep South Texas and the Rio Grande Valley
in the wake of the recent historic rains and flooding. According
to the Central Massachusetts Mosquito Control Project, "mosquitoes
function best at 80 degrees F(ahrenheit), become lethargic at 60
degrees F(ahrenheit), and cannot function below 50 degrees
F(ahrenheit)." Although daytime highs on Sunday through Wednesday
will gradually and increasingly warm over the course of these four
days, chilly lows on these mornings will mean a more enjoyable
time outdoors before midday due to a lessened threat from
mosquitoes.

&&

.AVIATION.../12z TAFS THROUGH 12Z SATURDAY/....
Issued at 620 AM CDT Fri Apr 4 2025

Key Aviation Messages:

* Low level wind shear (LLWS) expected to continue at the
  terminals from 12z-15z with peak 2,000 ft winds between 45-50
  kts.

* MVFR CIGS expected from 12z-15z this morning and again from 23z-06z
  later this evening/tonight.

* Strong south-southeast sfc winds 15-25 kts gusting as high as 40
  kts today.

Strong south-southeast winds due to an enhanced pressure gradient
due to an anomalously strong 550 mb trough/low pressure system over
the Rockies and an anomalously strong 591 mb ridge/sfc high off the
Southeastern U.S. Coast will be one of the weather concerns for the
terminals through the 24 hour 12z TAF cycle. MVFR CIGS will be
another weather concern during portions of the 12z TAF cycle due
to a strong capping inversion just above the sfc.

As of 6:24 AM CDT, GOES-16 Infrared and Nighttime Microphysics
Satellite imagery revealed a stratus and stratocumulus deck of
low level (MVFR) clouds with ceilings ranging between 1,500-2,500
feet AGL and unrestricted visibilities over the TAF sites with
higher level clouds riding overhead. Our 00z KBRO sounding from
this evening revealed a strong capping inversion between 930-860
mb, supporting the low stratus that we currently have in place.
Over the next few hours, expect for these low clouds to begin to
burn off eventually giving way to VFR conditions returning across
the terminals by mid to late morning. VFR conditions with sunny
skies and a few clouds will persist through the day today. Later
this evening/tonight, expect for MVFR CIGS to make a return due to
the marine layer moving onshore, mixing heights decreasing, and
possibly another capping inversion developing.

Given the synoptic setup coupled with local geographical
enhancements, breezy to windy conditions will persist through the
entire 12Z TAF cycle. This morning through at least this
afternoon, south-southeast winds will strengthen as mixing heights
increase to about 900 mb. This will result in windy conditions
with south-southeast winds 20-25 kts gusting as high as 40 kts or
so through the day today. These winds could persist/continue into
the evening hours later today.

Low level wind shear (LLWS) will be in play for all of the terminals
through 15z or so this morning. BUFKIT soundings and the VAD wind
profile reveals a decoupling of winds between the sfc and 2,000
feet AGL with south-southeast winds at 2,000 feet AGL reaching as
high as 45-50 kts. Observations also show sampled LLJ winds
between 06z-15z ranging between 40-50 kts over the region.

&&

.MARINE...
(Today through Saturday)
Issued at 340 AM CDT Fri Apr 4 2025

Today through Saturday...Hazardous marine conditions are expected
to continue through Saturday due to the effects of strong
southerly winds. A Small Craft Advisory remains in effect through
Saturday due to high seas. Additionally, a High Surf Advisory and
a High Risk for Rip Currents is in effect till Saturday evening.

(Saturday Night through Thursday)
Small Craft Advisory conditions are anticipated along the Lower
Texas Coast Saturday night through Sunday night due to the
Saturday daytime passage of a cold front. A gradual improvement in
winds and seas will then occur from Monday through Thursday with
persistent high pressure in control over the western Gulf of
America.

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             90  76  90  56 /   0   0  10  20
HARLINGEN               92  74  91  55 /   0   0  10  20
MCALLEN                 96  77  92  58 /   0   0   0  10
RIO GRANDE CITY         98  73  89  52 /   0   0   0  10
SOUTH PADRE ISLAND      81  75  81  57 /   0   0  10  20
BAYVIEW/PORT ISABEL     89  74  88  55 /   0   0  10  20

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...Wind Advisory until 9 PM CDT this evening for TXZ251-253>255-351-
     354-355.

     High Rip Current Risk through Saturday evening for TXZ451-454-
     455.

     High Surf Advisory until 7 PM CDT Saturday for TXZ451-454-455.

GM...Small Craft Advisory until 7 AM CDT Sunday for GMZ130-132-135-
     150-155-170-175.

&&

$$

SHORT TERM...23-Evbuoma
LONG TERM....66-Tomaselli
AVIATION...23-Evbuoma