636
FXUS64 KBRO 282330
AFDBRO

Area Forecast Discussion
National Weather Service Brownsville TX
630 PM CDT Sat Jun 28 2025

...New AVIATION...

.KEY MESSAGES...
Updated at 615 PM CDT Sat Jun 28 2025

 - The National Hurricane Center (NHC) is monitoring an area of
   low pressure over the Yucatan Peninsula, giving it a medium
   (50%) chance of tropical development over the next 48 hours.

- Increased tropical moisture will increase rain chances through
  the first part of the week with unsettled weather continuing
  through Thursday.

&&

.DISCUSSION...
(Tonight through next Saturday)
Issued at 1156 AM CDT Sat Jun 28 2025

The main story through the forecast period will be increasing
rain chances due to an influx of tropical moisture streaming in
from an area of low pressure in the Bay of Campeche in which the
National Hurricane Center is monitoring. Currently there is a
medium (50%) chance of development over the next next 2 days with
this system moving onshore into Mexico on Monday. The moisture
from this area of low pressure will move into Deep South Texas
increasing rain and thunderstorm chances Sunday and Monday
(60-80%), with highest chances across Willacy, Cameron, and
Hidalgo counties. Brief heavy downpours will be possible that
could lead to nuisance flooding, especially on roadways.

While rain chances will begin to decrease Monday night, lingering
tropical moisture remains in place and unsettled weather will continue
through the rest of the week, remaining highest along and east of
US-281. Tuesday chances are around 45% but by Thursday rain
chances drop off to around 25%, and less than a 15% chance for the
Fourth of July. This activity will be our typical diurnal, sea-
breeze type activity that will die off in the evening. Brief heavy
rain, cloud to ground lightning and gusty winds will be possible
in the strongest thunderstorms that develop.

Temperatures will cool a bit early week as we see more cloud cover
and rain chances thanks to excess tropical moisture, with highs
in the low to mid-90s but will rebound by late week back into the
mid to upper 90s. Overnight lows will remain in the mid to upper
70s. A Minor Heat risk is forecasted for much of Deep South Texas
through Wednesday, retuning to Moderate by Thursday and Friday.

At areas beaches, swell will increase Sunday into Monday due to the
potential tropical development in the Bay of Campeche. This will
lead to a moderate to high risk of rip currents for the first part
of the week.

&&

.AVIATION...
(00Z TAFS)
Issued at 615 PM CDT Sat Jun 28 2025

VFR conditions continue throughout tonight and east-southeasterly
winds (gusting to around 20-25 knots) continue this evening,
settling down beyond sunset. There is a chance for a brief shower
or two this evening, but confidence is not high enough to include
in the 00Z TAF package and minimal chances are expected overnight.
PROB30`s have been introduced beginning in the early morning and
morning hours at KBRO and KHRL, respectively, as well as for all
sites by 18 Z Sunday as passing showers and thunderstorms extend
across the Rio Grande Valley from a Tropical Depression in the Bay
of Campeche. MVFR conditions, heavy rain, frequent lightning and
stronger gusts are possible in the strongest thunderstorms.
Otherwise, southeasterly winds continue of similar magnitude as
today by the afternoon hours on Sunday.

&&

.MARINE...
Issued at 1156 AM CDT Sat Jun 28 2025

Generally favorable marine conditions are expected through period.
However, the National Hurricane Center indicates a medium (50%)
chance of tropical development in the Bay of Campeche. This could
lead to slightly elevated seas with Small Craft Caution likely on
Monday, mainly on the southern waters. Tropical moisture will stream
northward from the area of low pressure increasing rain and
thunderstorms chances, primarily Sunday and Monday, but lingering
chances remain through the week. This activity could locally enhance
winds and seas.

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             78  90  77  89 /  30  70  40  70
HARLINGEN               75  91  74  89 /  20  60  30  70
MCALLEN                 78  94  76  90 /  10  60  20  70
RIO GRANDE CITY         76  92  75  87 /   0  50  10  70
SOUTH PADRE ISLAND      79  87  78  86 /  40  70  40  70
BAYVIEW/PORT ISABEL     77  90  76  89 /  30  70  40  70

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...None.
&&

$$

DISCUSSION...55-MM
AVIATION...65-Irish