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000
FXUS64 KBRO 211721
AFDBRO

Area Forecast Discussion
National Weather Service Brownsville TX
1221 PM CDT Sun Apr 21 2024

...New AVIATION...

.UPDATE...
Issued at 1022 AM CDT Sun Apr 21 2024

A secondary cold front with a decent surge of cold air advection
is currently moving quickly southward across Cameron county as of
15Z. This secondary front will clear the CWA within the next hour
and effectively halt the brief warming (close to 80 degs) that
occurred at KBRO. Meanwhile across the remainder of the CWA, highs
essentially have already occurred with little to no recovery
expected today as CAA and thick cloud cover are maintained for
most of the CWA. Could see some brief warmup across portions of
Brooks and Kenedy counties late.

As for rain chances, still expecting additional showers and
thunderstorms to develop throughout the day and into the evening
hours as kinematic forcing from the front helps to lift the fairly
moist airmass.

&&

.SHORT TERM...
(Today through Monday)
Issued at 411 AM CDT Sun Apr 21 2024

A cold front is currently moving south across Deep South Texas and
is expected to be south of the Rio Grande River around sunrise.
Brownsville radar indicates a large cluster of showers and
thunderstorms well south of the Rio Grande Valley, moving farther
south across Northeast Mexico. Scattered showers and isolated
thunderstorms will linger through the morning and early afternoon
hours across the Rio Grande Valley as warm, humid air rises above
the frontal boundary. Today will be much cooler as breezy north
winds, cloudy skies and lingering rain prevail across the region.

High temperatures will reach the upper 60s across the Northern
Ranchlands and low 70s across the Rio Grande Valley, mainly this
morning. Temperatures are expected to steadily fall through the
afternoon into the 60s with the arrival of the cooler airmass.
Leaned towards a NBM/ConsShort/ConsAll blend or mix for temperatures
for today and tonight, as the NBM temperatures seemed a bit too
warm. Wind gusts around 20-30 MPH will be likely beginning by mid to
late morning. Winds will begin to diminish this evening as
high pressure settles into the region.

Lows tonight will fall into the mid 50s across the Rio Grande Plains
and the Northern Ranchlands and into the low to mid 60s across the
Rio Grande Valley and along the coast. Lingering low rain chances
will possible tonight and Monday.

A High Risk of Rip Currents will be likely along the Lower
Texas Coast today into tonight due to increasing seas. A Moderate
Risk of Rip Currents is expected on Monday.

&&

.LONG TERM...
(Monday night through Saturday)
Issued at 411 AM CDT Sun Apr 21 2024

Key Messages:

* Warmth and humidity increases through the week and into next
  weekend

* Becoming breezy Thursday through next Sunday

* Adverse marine conditions developing Thursday PM through Sunday

Dry and tranquil weather conditions will prevail through the long-
term forecast period with a ~1016 mb surface high pressure system in
place. Global deterministic forecast models and ensemble are
advertising a amplified ridge axis approaching from the west Tuesday
before being overhead on Wednesday. Thursday through next weekend,
an anomalously strong trough is expected to dive into the
Southwestern U.S. This in turn will result in downstream ridging
over the eastern half of the country with a southwest flow aloft
pattern over Deep South Texas. Near the sfc, the local forecast area
will be on the western flank of a high pressure system to the east.

A strengthening pressure gradient with low pressure systems over the
mountains of north-central Mexico will drive a strengthening low
level jet (LLJ) over the area. Ultimately, this will result in
breezy south-southeast winds over Deep South Texas and the Lower Rio
Grande Valley which will aid in stronger moist and warm air
advection (WAA) over the area Thursday through Sunday.

That said, we`ll see temperature and humidity levels rebound this
week into next weekend. Wednesday will start off with daytime highs
ranging between the upper 80s to lower 90s. By Saturday/Sunday of
next weekend, daytime highs will range between the lower 90s to
lower 100s with dewpoints in the lower 70s. Overnight lows are
expected to be in the lower to mid 70s for much of the long-term
period.

&&

.AVIATION...
(18Z TAFS)
Issued at 1139 AM CDT Sun Apr 21 2024

MVFR and IFR ceilings will persist through most of the TAF period
across the three RGV TAF locations. This will be the result from
warm and moist air continuing to ride atop cooler sfc-based air
behind this morning`s cold front. Gusty north to northeast flow
will gradually weaken during this afternoon and evening.
Meanwhile, additional showers with embedded thunderstorms are
expected to develop this afternoon and persist through at least
this evening given this persistent lifting of the warm and moist
airmass. This is line with the last several runs of the HRRR and
several of the main synoptic model runs which depicted scattered
convection across the RGV.

&&

.MARINE...
Issued at 411 AM CDT Sun Apr 21 2024

Now through Monday...A cold front is currently moving through the
Lower Texas Coast waters. The front should be south of the Rio
Grande River around sunrise. In the wake of the front, increasing
winds and building seas will result in Small Craft Advisory
conditions along the Laguna Madre through later this evening and on
the Gulf waters late tonight. Small Craft Advisories may be needed
for offshore Gulf of Mexico waters on Monday. Additional scattered
showers and isolated thunderstorms will be possible through the
period.

Monday Night through Saturday Night....The long-term period will
start off Monday night into Tuesday with favorable marine
conditions with light to moderate winds and seas. By the time we
get into Thursday PM into next weekend, more adverse marine
conditions are expected to develop amid the tightening of the
pressure gradient and strengthening of boundary layer winds. Small
Craft Exercise Caution conditions will be possible Thursday PM
through Friday PM before Small Craft Advisory conditions become
possible over next weekend.

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             79  65  74  66 /  50  30  20  10
HARLINGEN               76  62  74  62 /  40  30  20   0
MCALLEN                 69  62  74  63 /  40  30  20   0
RIO GRANDE CITY         66  59  72  61 /  60  30  20   0
SOUTH PADRE ISLAND      76  68  72  69 /  50  30  20  10
BAYVIEW/PORT ISABEL     77  65  74  66 /  40  30  20  10

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...High Rip Current Risk through Monday morning for TXZ451-454-455.

GM...Small Craft Advisory until 10 PM CDT this evening for GMZ130-132-
     135.

     Small Craft Advisory until 7 AM CDT Monday for GMZ150-155-170-
     175.

&&

$$

SHORT TERM...63-KC
LONG TERM....23-Evbuoma
AVIATION...80-MB