427
FXUS64 KBRO 021120 AAA
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
620 AM CDT Tue Jul 2 2024

...New AVIATION...

.SHORT TERM...
(Today through Wednesday)
Issued at 337 AM CDT Tue Jul 2 2024

500 mb high pressure,
centered over the Gulf Coast states, will remain the dominant
weather feature over the BRO CWFA through the period. This will
produce rain-free conditions across Deep South Texas, the Rio Grande
Valley, and the adjacent coastal waters.

Temperature-wise, with the presence of the aforementioned mid-level
high, daytime highs and overnight lows will be in the slightly above
normal range. Despite relatively robust atmospheric moisture
(precipitable water values more or less around 2 inches), heat
indices will not reach established HEAT ADVISORY criteria. As a
result, will mention heat index values in a SPECIAL WEATHER
STATEMENT today and likely again tomorrow.

&&

.LONG TERM...
(Wednesday night through Monday)
Issued at 337 AM CDT Tue Jul 2 2024

Key Message:
* All eyes on Beryl and its future track and potential impact in
  the southwestern/western Gulf this weekend.

The long term continues to be a tale of two forecasts: The
easy...then the hard. Beginning with the easy (Wednesday night
through Friday night): The dominant and seasonably strong 500 mb
ridge remains anchored from west to east along 30-35N latitude,
stretching from southern California through nearly all of Texas
and east through the southern U.S.through Friday. This will
maintain weak surface ridging across the northern and eastern
Gulf with general south to southeast flow between it and the
typical west Texas through the lee of Sierra Madre trough, keeping
slightly above seasonal average temperatures by day and night with
no rainfall.

The "hard" begins Saturday and continues through Monday. All eyes
will be on Beryl, as well as the evolution of the aforementioned
ridging. Over the past few runs, the global and some of the
hurricane models have been trending for a slightly deeper trough
to develop and dig across the central and even the southern Plains
into the Mississippi Valley, splitting the strong ridge in two,
with the western portion retrograding to California while the
eastern portion slides to the southeast U.S. coast. This morning`s
early models follow their deterministic biases...with the
ECMWF with higher heights and a more southern track into Mexico,
but the GFS now a bit farther north, just off of the Lower Texas
coast by late this weekend. The Canadian GEM has "flopped" back to
a more southern track...owing to a stronger steering ridge.
Hurricane models and the extrapolated consensus of them suggest a
much closer approach toward the mouth of the Rio
Grande/northeastern Tamaulipas on Sunday.

Bottom line? A lot of uncertainty remains, and confidence remains
low in exactly how the latter half of the Fourth of July weekend
plays out. Here`s what we know this morning:

* Beryl will weaken across the western Caribbean and along its
  track through the Yucatan...assuming it still crosses a good
  portion of it and doesn`t clip the northern end of it. Wind
  shear will do the job, and the current forecast brings Beryl
  down to a Tropical Storm when re-emerging over the Bay of
  Campeche.

* The aforementioned digging trough into the central/southern
  Plains is becoming a bigger factor in forecast trends, and Beryl
  is more likely to "feel" it than not. That will cause at least a
  northwest movement by Saturday or Sunday, keeping the Valley in
  play for at least some potential impacts.

What we still don`t know is how the wind shear profile will evolve
over the southwest/western Gulf five days from now. Weaker shear
would allow at least modest restrengthening; stronger shear would
keep the future Beryl more susceptible to weakening. We also don`t
know whether Beryl will expand much more in size during this
period. Through the Caribbean trek and into the Yucatan, the
cyclone will remain rather compact...and compact cyclones are more
susceptible to disruptions from wind shear and dry air.

For now...the sensible weather forecast remains largely the same
for Saturday through Monday, with modest increases in rain chances
and slight downward nudges in temperatures. The Weather Prediction
Center`s deterministic QPF was knocked down to limit rainfall
generally along/east of IH-69C, and total rainfall generally below
1 inch (with locally higher amounts). At minimum, we`ll see
another round of dangerous surf and rip currents for average to
poor swimmers, as well as some tidal run-up.

At maximum? We just can`t say yet...but there is certainly a non-
zero chance of much more rain, stronger winds, notable coastal
flooding, and life-threatening surf. Hopefully, the steering setup
becomes consistent in the next couple of days and we`ll have a
better idea...and confidence...on the track.

Regardless...keep those preparedness plans on the front burner
and be ready to begin actions as soon as the Fourth.

&&

.AVIATION...
(12Z TAFS)
Issued at 619 AM CDT Tue Jul 2 2024

Generally VFR conditions are anticipated at the aerodromes through
the next 24 hours.

&&

.MARINE...
Issued at 337 AM CDT Tue Jul 2 2024

Today through Wednesday...Buoy 42020 reported south winds around
14 knots gusting to around 16 knots with seas slightly under 4.5
feet with a period of 8 seconds at 1:50 CDT/6:50 UTC. High
pressure over the western Gulf of Mexico will produce light to
moderate winds and low to moderate seas along the Lower Texas
Coast through the period. Small Craft Should Exercise Caution and
Small Craft Advisory are not anticipated to be needed.

Wednesday Night through Friday Night...High pressure across most
of the Gulf will keep conditions fairly copacetic...with moderate
southeast winds and slight to moderate seas with no appreciable
rainfall.

Saturday and Saturday Night...Much will depend on the evolution of
Beryl (size, strength, forward motion, etc.). For now, we`ve held
onto seas building to 4 to 6 feet with the arrival of the swell
train. Model forecasts suggest wave period could rise quickly to
12-14 seconds, which could generate wave heights up to 8-9 feet by
Saturday night. Winds could also begin to pick up across the Gulf
waters and reach 20+ knots at night...and the conditions and
future forecast will depend on any Tropical Watch/Warning
disposition at that time. Should the cyclone near the waters, the
associated rain squalls would arrive as well. Small craft
operators as well as shippers should stay updated daily on the
trends with Beryl and plan accordingly.

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             95  80  94  82 /   0   0   0   0
HARLINGEN               96  77  96  77 /  10   0  10   0
MCALLEN                 98  80  98  80 /   0   0   0   0
RIO GRANDE CITY         97  78  98  79 /   0   0   0   0
SOUTH PADRE ISLAND      88  83  89  84 /   0   0   0   0
BAYVIEW/PORT ISABEL     93  79  93  80 /   0   0   0   0

&&

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

&&

$$