FXUS64 KBRO 211145 AAA
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
645 AM CDT Wed May 21 2025

...New AVIATION...

.SHORT TERM...
(Today through Thursday)
Issued at 350 AM CDT Wed May 21 2025

A weak frontal boundary stalled across northern ranchlands early 
this morning will move northward as a warm front later this morning. 
Latest surface observations indicate some patchy fog has developed 
across portions of the area, but the fog is expected to dissipate by 
the mid morning.

The combination of the weak frontal boundary to the north, a mid-
level short wave approaching from the west, and abundant moisture 
(PWATs around 2 inches) will support a low to medium (20 to 40 
percent) chance of showers and thunderstorms this afternoon into 
tonight. However, there is a low (20 percent or less) chance of rain 
this morning with the increased moisture content and the frontal 
boundary across the region. The latest CAMs/guidance suggest that 
some convection will develop over the Sierra Madre this afternoon 
and move northeast to east towards the Rio Grande River. The 
thunderstorms that do develop this afternoon into tonight could have 
the potential to become severe, with the main threats being damaging 
wind gusts and hail. SPC has most of Deep South Texas in a Marginal 
Risk of severe weather for today into tonight. WPC has painted the 
western portions of the CWA, including Zapata, Starr, Jim Hogg and 
portions of Brooks and Hidalgo counties, in a marginal risk (level 1 
of 4) of excessive rainfall for today and tonight. Rain chances end 
from west to east late tonight into Thursday morning as the upper 
level disturbance swings eastward.

Otherwise, increase cloud cover should keep temperatures slightly 
lower today (near normal) with highs in the low to mid 90s, except 
for the 80s at the beaches. Cloudy and mild tonight with lows in the 
mid to upper 70s. Highs on Thursday will be a degree or two higher 
than today. There is a Moderate Heat Risk (Level 2 of 4) for all of 
Deep South Texas today and Thursday. 

There is a Moderate Risk of rip currents at local beaches today 
decreasing to a Low Risk tonight and Thursday.

&&

.LONG TERM...
(Thursday night through Tuesday)
Issued at 350 AM CDT Wed May 21 2025

Upper-level ridging looks to set up over the Central US Friday and 
continue through the weekend. This pattern will support generally 
rain free conditions and a gradual warming trend through the 
weekend. An upper-level trough looks to work it’s way across the 
Central Plains early next week, which could drive a cold front 
south, approaching the area late Monday or Tuesday. With the front 
pushing south, rain chances and cloud cover look to increase early 
next week, which could support slightly cooler temperatures early 
next week.

High temperatures look to return to the upper 90s to low 100s over 
the weekend, before falling to the upper 80s to low 90s early next 
week. Heat indices look to remain just below Heat Advisory criteria 
this weekend.

&&

.AVIATION...
(12Z TAFS)
Issued at 636 AM CDT Wed May 21 2025

A mix of IFR/MVFR ceilings with light northeast to east winds 
prevail across Deep South Texas early this morning. Will mention a
TEMPO until 14Z for IFR ceilings and patchy fog. Ceilings are 
expected to gradually lift to VFR levels later this morning into 
the afternoon. There is a medium chance for some convection to 
move into portions of the area later this afternoon into this 
evening, especially at MFE. Confidence remains low for convection 
impacting HRL/BRO at this time. 

&&

.MARINE...
Issued at 350 AM CDT Wed May 21 2025

Today through Thursday...Buoy020 reported southeast winds around 6 
knots with gust of 8 knots and seas near 3.9 feet early this morning.
Favorable conditions will prevail along the lower Texas coast 
through the period with light to moderate east to southeast winds 
and low to moderate seas. Some patchy fog may develop early this 
morning over the Gulf waters and Laguna Madre, but will dissipate 
later this morning. There is a low chance (20 percent) of showers 
and thunderstorms today and tonight. 

Thursday night through next Tuesday...Generally favorable marine 
conditions are expected at the start of the period. Pressure 
gradients along the Lower Texas Coast are expected to increase 
over the weekend, supporting stronger winds and seas across the 
coastal waters. Small Craft Should Exercise Caution headlines may 
be needed Saturday and Sunday. Light to moderate onshore winds and
slight to moderate sea look to return by Monday, with generally 
favorable conditions continuing through the remainder of the 
period.

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             91  78  92  78 /  20  20  10   0 
HARLINGEN               92  75  92  75 /  30  20  10   0 
MCALLEN                 95  77  96  78 /  30  30  10  10 
RIO GRANDE CITY         95  74  96  76 /  40  40  20  10 
SOUTH PADRE ISLAND      84  79  85  79 /  20  10  10   0 
BAYVIEW/PORT ISABEL     87  76  89  77 /  20  20  10   0 

&&

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

$$

SHORT TERM...63-KC
LONG TERM....60-BE
AVIATION...63-KC