205
FXUS64 KBRO 131043 AAA
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
543 AM CDT Thu Jun 13 2024

...New AVIATION...

.SHORT TERM...
(Today through Friday)
Issued at 246 AM CDT Thu Jun 13 2024

The greatest extent for isolated showers and thunderstorms is
anticipated for today, as precipitable water values around 2
inches combines with 500 mb high pressure that will remain
centered over southern New Mexico. Indeed, HRRR guidance suggests
pockets of isolated convection moving north-northeast to south-
southwest across Deep South Texas and the Rio Grande Valley,
especially during the late afternoon hours.

On Friday, the center of the mid-level high will move into Oklahoma,
while precipitable water values fall to around 1.5 inches. The
result will be an even lesser chance for showers and thunderstorms,
with the greatest likelihood of them progged to be generally along
and east of the Interstate 69E corridor.

Temperature-wise, even with 500 mb high pressure becoming more of a
factor during the period, above normal temperatures are forecast,
and not well above normal. This will result in a HEAT ADVISORY not
likely for today and Friday, so will instead manage the heat indices
with a SPECIAL WEATHER STATEMENT on both of those days.

&&

.LONG TERM...
(Friday night through Wednesday)
Issued at 246 AM CDT Thu Jun 13 2024

Most of the same train of thought continues to carry over with this
forecast package for the long term forecast. The two big stories to
really talk about happen to be very connected with one another. The
first of which is the potential for rainfall as an inverted trough
moves westward over the Gulf of Mexico during the early part of the
work week, and the second is the potential development of a tropical
cyclone during the early work week in the Bay of Campeche.

Starting with the rain chances for Deep South Texas and the Rio
Grande Valley, there are some isolated showers and thunderstorms
that try to get going on Saturday with the diurnal sea breeze.
However that rain chances are expected to be more limited to the
Lower Rio Grande Valley on that day. Rain chances start to pick up
more on Sunday, as the middle and upper levels of the atmosphere
become more moist allowing for a more favorable environment for the
development of showers and thunderstorms. However rain chances are
still only isolated on Sunday. Starting on Monday, the rain chances
will increase further and further each day through Wednesday based
on the latest model guidance. With rain chances getting up to around
60 percent by Wednesday and all of Deep South Texas and the Rio
Grande Valley having some form of rainfall potential, there is a
very good chance of getting much needed rainfall.

However, there is an interesting twist to the potential for rainfall
that is tied to the potential development of a tropical cyclone down
in the Bay of Campeche. While the environment is certainly
favorable for a Tropical Depression or a weak Tropical Storm to
develop. The synoptic flow patterns would steer the center of this
system to making landfall somewhere around Tampico and Veracruz. At
this current time, the National Hurricane Center has increased the
chances of formation to 40 percent, and further increases likely to
occur based on the current model guidance. Something to watch for in
further forecast shifts is that if this system becomes stronger, the
potential for rain for Deep South Texas and the Rio Grande Valley
will actually start to decrease as more of the tropical moisture is
pulled closer to the storm and the heavier rainbands will remain to
the south of the region. However, since this tropical cyclone has
yet to develop, current thought process is to go with a more
widespread rainfall scenario.

The much needed rainfall is not the only impacts that will be felt
over the course of the long term forecast period. Because of the
enhanced pressure gradient a stronger easterly to southeasterly flow
will develop that will generate bigger swell that will in turn lead
to a higher risk of rip currents along the beaches and even some
coastal flooding concerns as well during the early part of the work
week.

As for the temperatures for the long term forecast period, the highs
will start off in the range of upper 90s for most of Deep South
Texas and the Rio Grande Valley, with a few areas in the triple
digits, but will decrease over the period to being mostly in the 90s
thanks to all the cloud coverage that is expected to move in. Heat
indices are expected to be in the range of 105-110 thus staying out
of Heat Advisory criteria, but could still warrant a Special Weather
Statement. The low temperatures on the other hand, will be mostly in
the 70s, but a few places could toe into the low 80s at times.

&&

.AVIATION...
(12Z TAFS)
Issued at 540 AM CDT Thu Jun 13 2024

VFR will continue to be the rule at the aerodromes through the
next 24 hours. Light to moderate winds with limited cloud cover
is also anticipated, with little to no chance of rain.

&&

.MARINE...
Issued at 246 AM CDT Thu Jun 13 2024

Today through Friday...Surface high pressure centered generally
over Louisiana will continue to be the dominant weather influence
over the western Gulf of Mexico through the period. Light to
moderate winds and low to moderate seas are anticipated along the
Lower Texas Coast, with neither Small Craft Should Exercise
Caution nor Small Craft Advisory likely to be needed.

Friday Night through Wednesday...Mostly favorable conditions for the
weekend as light to moderate easterly winds with low seas are
expected with some showers and thunderstorms possible. However, as
an inverted trough moves across the Gulf of Mexico, there is the
potential for the development of a tropical cyclone during the early
part of the work week. The enhanced swells that will be generated by
this system will likely result in adverse and hazardous conditions
that will require Small Craft Advisories through Wednesday.

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             96  79  95  79 /  20  10  30  10
HARLINGEN               97  75  96  75 /  30   0  20  10
MCALLEN                 99  79  99  78 /  20   0  10   0
RIO GRANDE CITY         99  78  99  76 /  10   0   0   0
SOUTH PADRE ISLAND      88  82  88  82 /  30  10  30  10
BAYVIEW/PORT ISABEL     93  79  92  79 /  20  10  30  10

&&

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

&&

$$