204
FXUS64 KBRO 171742
AFDBRO

Area Forecast Discussion
National Weather Service Brownsville TX
1242 PM CDT Tue Jun 17 2025

...New SHORT TERM, LONG TERM, AVIATION, MARINE...

.KEY MESSAGES...
Updated at 1242 PM CDT Tue Jun 17 2025

 - Unsettled weather returns on Thursday and continues through
   early next week.

 - There is still uncertainty on where the higher rainfall amounts
   will set up, so continue to check back for updates to the
   forecast.

 - Take time during this drier period of weather to clean out
   drainage ditches, canals, etc.

&&

.SHORT TERM...
(Tonight through Wednesday night)
Issued at 1242 PM CDT Tue Jun 17 2025

The short term period will feature slightly above normal
temperatures and generally rain-free conditions across Deep South
Texas as mid-level ridging builds overhead. At the lower levels,
persistent low-level southerly to southeasterly flow will maintain
elevated dew points across the region. In combination with warm
afternoon temperatures, will result in afternoon heat index values
ranging from 100-110 degrees. There will be a moderate (level 2 of
4) heat risk for all of Deep South Texas on Wednesday, so continue
to practice heat safety to prevent any heat-related illnesses.

&&

.LONG TERM...
(Thursday through next Tuesday)
Issued at 1242 PM CDT Tue Jun 17 2025

An unsettled weather pattern will prevail for most of the long
term period across Deep South Texas due to an influx of deep,
tropical moisture from the southern Gulf. Expect low to medium
(20-60%) daily precipitation chances beginning on Thursday, and
continuing into early next week. However, the latest ensemble,
deterministic, and probabilistic guidance reveals there are still
discrepancies on the timing, coverage, and northward extent of the
highest precipitable water values, which will result in changes
to the QPF forecast, especially across the Rio Grande Valley. The
main change with this update is lower rainfall amounts for the
low/mid RGV, but expect additional changes to the forecast over
the next several days.

Precipitable water values are expected to rise above 2-2.2 inches
across the low/mid RGV by Thursday afternoon/evening and remain
anomalously high through early next week, aided by deep south to
southeasterly flow. Overall, this should allow for daily scattered
showers and thunderstorms across the Rio Grande Valley and
immediate coast, which is where the better moisture content will
reside. Given the favorable environment, any development will
likely be able to produce locally heavy rainfall of 1-2 inches.
Probabilistic guidance does highlight the potential for locally
heavy rainfall, mainly over portions of Cameron County, with a low
to medium chance (20-40%) of rainfall amounts greater than 1 inch
on Friday, and low chances (~20%) of amounts greater than 1 inch
each day this weekend. While the deterministic NBM did trend
toward lower precipitation amounts Friday through the weekend, the
NBM 75th percentile indicates locally higher amounts upwards of
2.5 inches cannot be ruled out for the low/mid RGV.

Otherwise, increased cloud cover and rain chances should result in
near to slightly below normal temperatures, with highs generally
in the low 90s and lows in the low to mid 70s.

&&

.AVIATION...
(18Z TAFS)
Issued at 1242 PM CDT Tue Jun 17 2025

VFR will prevail through the forecast period at all TAF sites. FEW
to SCT MVFR ceilings may develop along the immediate coast late
tonight into tomorrow morning. Otherwise, southeast winds around
10-15 knots with gusts to 25-30 knots will prevail this afternoon,
with gusts subsiding this evening and returning by mid morning on
Wednesday.

&&

.MARINE...
Issued at 1242 PM CDT Tue Jun 17 2025

Generally favorable marine conditions will prevail through the
weekend with low to moderate seas and light to moderate southeast
winds. A locally enhanced pressure gradient may result in periods
of Small Craft Exercise Caution conditions during the afternoon
hours along the Laguna Madre and nearshore Gulf waters through the
end of the week. Otherwise, there is a medium to high chance (50-
80%) of showers and thunderstorms beginning Thursday and
continuing through the weekend. Locally enhanced winds and seas
are likely within showers and thunderstorms.

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             81  94  80  93 /   0  10  20  60
HARLINGEN               78  96  78  94 /   0   0  10  60
MCALLEN                 79 100  80  98 /   0   0   0  50
RIO GRANDE CITY         77  99  78  96 /   0   0   0  30
SOUTH PADRE ISLAND      81  88  81  88 /   0  10  20  60
BAYVIEW/PORT ISABEL     79  93  80  91 /   0  10  10  60

&&

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

$$

SHORT TERM...22-Garcia
LONG TERM....22-Garcia
AVIATION...22-Garcia