943
FXUS64 KBRO 210022 AAA
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
722 PM CDT Thu Jun 20 2024

...New UPDATE, AVIATION, MARINE...

.UPDATE...
Issued at 722 PM CDT Thu Jun 20 2024

As of 7 pm...observed minus predicted tide levels remained right
around 3 feet at all three observing platforms along Laguna Madre
Bay and just inshore of South Padre Island. With continued
pounding surf and Buoy 42020 still carrying 12 foot seas and 11
second swell period...as well as distant Buoy 42002 still at 10-11
feet and 8-10 second period...see no reason why the departure will
change much into Friday`s high tide cycle. So...expect water
values above mean higher high water...a reasonable approximation
for above ground at the shoreline interface...to be between 2.5
and 2.75 feet again Friday morning through noon which is enough to
maintain severe beach erosion and cause potential damage to docks
and property exposed along baysides. For this reason...extended
the Coastal Flood Warning through 1 PM Friday and replaced with an
advisory for lower, more minor flood values during the afternoon
when low tide combines with slowly receding tide water values.

The High Surf Warning...issued for 12 foot and otherwise dangerous
surf waves...was replaced with a High Surf Advisory for surf
waves sliding to between 6 and 9 feet overnight but also
continuing through most of Friday.

&&

.SHORT TERM...
(Tonight through Friday night)
Issued at 240 PM CDT Thu Jun 20 2024

Key Messages:

- Heavy Rain Potential continues tonight and Friday
- Overall Rain Chances Lower
- Coastal Flood Warning replaced by Flood Advisory tonight

In a nutshell tropical moisture remains elevated over the region
with scattered to numerous showers and isolated thunderstorms
continuing to track steadily and quickly westward. Pockets of heavy
with rainfall rates of 1-2 in/hr are noted with these shwrs/tstm but
with the quick pace flooding is not being observed. Tonight
convection should wane but not end with a continued chance of
additional convection Friday as differential  heating and
instability increases.  The National Blend of models (NBM) remains
rather stout on the PoPs over the next 24-36 hours so trended with a
more reserved CONSALL blend which shows 40-60 percent. Maintained
the mention of heavy rain through the period with forecast
precipitable water values in the 1.7-2 inch range. Pressure gradient
relaxes tonight as the remnants of former TS Alberto continue to
move west and dissipated over Mexico. Wind gusts should drop off
rapidly after sunset if not earlier with moderate east winds gusting
around 20 mph Friday due to a a general climatological onshore sea
breeze. Temperatures have recovered somewhat today with elevated dew
point pushing the heat index over 105 degrees for much of the CWA.
Warm and very muggy tonight and again Friday night with lows only 75-
80 degrees. Another typical hot day Friday with highs expected in
the low 90s and heat indices topping out 105-110 degrees.

Coastal flooding is forecast to ease slightly tonight as the tide
cycle approaches low tide around 830 pm.  Swells over the Gulf and
the off the lower Texas coast to remain elevated with a slow
subsidence through Friday. With the overall trend for lowering tides
the next 12-18 hours we will let the coastal flood warning expire at
7 PM and replace with an coastal flood advisory through Friday. With
this said, the combination of persistent elevated swells and with
tide cycle approaching high tide at 715 AM Friday some tidal
overwash exceeding the dune line on narrow beaches is possible early
Friday morning but this should be the exception to the rule.  Also,
Rip current risk to remain high with dangerous swimming conditions
tonight, Friday and Friday night.

&&

.LONG TERM...
(Saturday through next Thursday)
Issued at 240 PM CDT Thu Jun 20 2024

The long term period will feature continued precipitation chances
and near normal to slightly below normal temperatures across Deep
South Texas. Mid/upper level ridging will have shifted back over
the Southern Plains by Saturday, but all eyes will be on the
Southern Gulf of Mexico where another tropical system may develop
over the weekend or early next week. The latest deterministic
guidance indicates that should any system develop near the Bay of
Campeche, it would likely follow a track similar to Tropical
Storm/Depression Alberto and move west northwestward toward
Mexico. The National Hurricane Center currently has a 20% chance
of development through the next 48 hours, and a 50% chance of
development through the next 7 days.

Regardless of any tropical development, persistent southerly to
southeasterly flow will maintain a well established influx of
tropical moisture over Deep South Texas through mid week next
week. In combination with daytime heating during the late morning
and afternoon hours, isolated to scattered showers and
thunderstorms will develop over the weekend each day. Given the
beneficial rainfall we received with Tropical Storm Alberto,
additional rainfall may pose a threat for isolated instances of
flash flooding, especially in flood-prone areas. The latest
guidance indicates rainfall amounts through mid week will range
from around 0.75-2.5 inches, with higher amounts closer to the
coast.

&&

.AVIATION...
(00Z TAFS)
Issued at 722 PM CDT Thu Jun 20 2024

With Alberto out of the picture and deep layer moisture on the
wane...have backed off a bit on overnight precipitation as diurnal
trend should take over, especially at inland terminals. While
there may be a quick-hitting shower until 9 or 10 PM inland,
expect skies to generally clear and winds diminish to 10 knots or
less. Brownsville may hold up a bit and would not surprise to see
winds hang tough a bit longer into the late evening.
Otherwise...generally MVFR scattered conditions with a few broken
periods this evening. On Friday, easterly winds pick up within a
few hours of sunrise but nowhere near as strong today as gradient
finally weakens. Moisture also thins out but owing to just enough
remaining and the slightly lower winds, scattered showers and
perhaps a thunderstorm could develop. For now, kept to showers but
maintained a PROB30 mention for mid afternoon at all sites.

&&

.MARINE...
Issued at 722 PM CDT Thu Jun 20 2024

Updated: Made two minor changes to the hazards. First, due to the
still dangerous seas over 10 feet and long period swell that keeps
them there, extended the Gulf advisory (for 7+ foot seas overall)
through 7 PM Friday. For Laguna Madre, kept the advisory through 7
AM as before but ended it then. Expecting diminishing winds over
Laguna but may take longest over the Bay between SPI and Port
Isabel...so for now held on even though conditions may drop into
caution levels farther north by midnight and even over the Bay
between 3 and 6 AM. Will let next shift evaluate the situation and
possibly trim back further by midnight or so.

&&

.MARINE...
Issued at 240 PM CDT Thu Jun 20 2024

Tonight through Friday night...Winds and seas remain elevated
with 2 PM CDT observation from buoy 42020 showing east winds 23
gusting 29 knots and seas at 14 ft with an 11 second period. The
stout onshore flow and elevated seas begin to lower this evening
and more so Friday as the remnants of former tropical storm
Alberto continue to move west over inland Mexico. The pressure
gradient over the entire Gulf of Mexico should remain moderately
strong as high pressure builds over the Southern Gulf States and
combines with another broad low pressure area emerging over the
Yucatan Peninsula Friday night. Although easterly winds should
drop below Small Craft Advisory (SCA) conditons late tonight or
Friday morning the elevated seas are likely to take all day to
drop below SCA levels (7 feet) if they do. The current SCA is
valid through 7 AM Friday and may be extended mainly for the Gulf
waters. Exercise caution is likely for the Laguna Madre Friday and
may drop below 15 knots Friday night.

Saturday through Thursday...Light to moderate winds and moderate
seas are expected through the next several days. However, winds
and seas will be highly dependent on the potential development of
a tropical system in the southern Gulf of Mexico. The NHC has a
50% chance for tropical cyclone formation in the next 7 days.
Small Craft Exercise Caution to Small Craft Advisory conditions
cannot be ruled out over the weekend, and any development in the
Gulf of Mexico could drastically change the forecast. Favorable
marine conditions will return by Tuesday or Wednesday of next
week.

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             80  92  78  89 /  60  60  50  80
HARLINGEN               76  92  75  90 /  50  60  50  80
MCALLEN                 78  92  76  90 /  60  60  40  80
RIO GRANDE CITY         77  90  75  87 /  70  60  30  70
SOUTH PADRE ISLAND      83  87  81  86 /  60  40  50  80
BAYVIEW/PORT ISABEL     80  89  78  88 /  60  40  50  80

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...Coastal Flood Warning until 1 PM CDT Friday for TXZ351-354-355-
     451-454-455.

     Coastal Flood Advisory from 1 PM to 7 PM CDT Friday for TXZ351-
     354-355-451-454-455.

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

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

GM...Small Craft Advisory until 7 AM CDT Friday for GMZ130-132-135.

     Small Craft Advisory until 7 PM CDT Friday for GMZ150-155-170-
     175.

&&

$$

SHORT TERM...52-Goldsmith
LONG TERM....66-Tomaselli
AVIATION...52-Goldsmith