Weslaco, Texas Weather Forecast Discussion

895
FXUS64 KBRO 240558 AAA
AFDBRO
Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
1258 AM CDT Wed Sep 24 2025
...New AVIATION...
.KEY MESSAGES...
Updated at 1253 AM CDT Wed Sep 24 2025
* Hot and humid with isolated chances for showers and thunderstorms
  again on Wednesday; Major (Level 3 of 4) Heat Risk expected with
  heat indices between 105-113F.
* Strong to severe thunderstorms are possible Wednesday night into
  Thursday; heavy rainfall, lightning, and strong winds will be the
  primary threats.
* There is a Marginal (Level 1 of 5) Risk for severe thunderstorms
  across the Northern Ranchlands Wednesday night into Thursday.
* There is a Marginal (Level 1 of 4) Risk for Excessive Rainfall
  across Brooks, Jim Hogg, and Zapata Counties Wednesday night into
  Thursday.
* Low grade (20-30%) chances for showers and thunderstorms will
  continue for much of the forecast period from Friday to
  Wednesday of next week with cooler/near normal temperatures.
&&
.DISCUSSION...
Issued at 1024 PM CDT Tue Sep 23 2025
The main weather headline during the forecast period will focus on
the potential for strong to severe thunderstorms along with locally
heavy rainfall in the Wednesday night through Thursday timeframe as
a cold front advancing southward across the state of Texas
approaches the region. Afterwards, an unsettled or somewhat
unsettled weather pattern remains on the table with day-to-day or
near day-to-day chances for showers and thunderstorms.
We start off the forecast period on Wednesday, that will feature
another warmer than normal, humid day with mainly rain-free
conditons. While most will experience rain-free conditions, there is
an isolated to widely scattered chance (20-30%) for showers and
thunderstorms to develop amid increased diurnal heating, elevated
precipitable water (PWAT) values, and some sea breeze interactions.
Wednesday is also progged to be our warmest day of the forecast
period with readings topping out in the mid 90s near the Lower Texas
Coast to the lower 100s west of IH-69C. Peak heat indices are
expected to range between 105-113F degrees, which will result in
Major (Level 3 of 4) Heat Risk.
Wednesday-Wednesday night, a line of strong to severe thunderstorms
driven by increased positive vorticity advection (PVA) and sfc
convergence in addition to an unstable airmass will be taking place
across central Texas. Hi-res CAM guidances are suggesting this
activity shifting southward in conjunction with the aforementioned
southward advancing cold front. There still remains uncertainties in
how far south the cold front will reach, but forward momentum from
the line of showers and storms to our north could reach into Deep
South Texas in the Wednesday night to Thursday timeframe. PoPs are
expected to increase from low to medium (20-40%) chances Wednesday
night (highest across the Northern Ranchlands) to categorical (55-
70%) chances on Thursday.
Should these storms continue southward into Deep South Texas, Sfc-
Based CAPE (SBCAPE) values between 1,000-2,000 J/kg and Downdraft
CAPE (DCAPE) values between 500-1,500 J/kg will support the threat
for strong to severe thunderstorms capable of producing damaging
winds. The Storm Prediction Center (SPC) has an isolated or Marginal
(Level 1 of 5) Risk for severe thunderstorms for the Northern
Ranchlands on Wednesday night in its SWODY 2, with damaging winds
being the primary threat.
Additionally, the Weather Prediction Center (WPC) has a Marginal
(Level 1 of 4) Risk for Excessive rainfall for our northwestern
sections that includes Brooks, Jim Hogg, and Zapata Counties in its
Day 2 ERO for Wednesday night into Thursday. While heavy rainfall is
expected with any storms, dry antecedent soils and high FFGs will
limit the widespread threat for flooding across these areas.
With the cold front potentially stalling out over the region or just
to the north, another round of showers and thunderstorms could take
place Thursday afternoon/evening, coinciding with peak sfc heating.
Categorical (80-90%) chances for PoPs remain in place through the
day on Thursday.
Rain chances begin to decrease on Friday as the aforementioned cold
front either washes out or shifts south into northeastern Mexico.
Rain-free conditions are expected to persist through Saturday night
with high pressure in control over the region and to our north.
Sunday through Wednesday, there are low grade chances (20-30%) for
isolated to widely scattered showers and thunderstorms areawide.
Temperatures Thursday through Wednesday of next week will average
out closer to normal levels with highs in the lower 90s and lows in
the upper 60s to mid 70s.
&&
.AVIATION...
(06Z TAFS)
Issued at 1253 AM CDT Wed Sep 24 2025
Predominately VFR conditions are expected to persist through the
period. There is a low chance for some isolated showers or
thunderstorms to develop this afternoon. The probability of any
showers or thunderstorms moving over an airfield is too low to
include in the TAFs. However, if a storm does move over an
airfield, conditions could briefly drop to MVFR levels.
Otherwise light southeasterly winds are expected to continue
through the morning, with wind gusts increasing around noon.
&&
.MARINE...
Issued at 1024 PM CDT Tue Sep 23 2025
Outside of the chance for showers and thunderstorms, marine
conditions will be favorable with low to moderate winds and seas
through the forecast period.
&&
.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             94  79  92  77 /  20  20  90  70
HARLINGEN               96  75  92  73 /  20  20  90  50
MCALLEN                101  79  95  76 /  10  20  90  50
RIO GRANDE CITY        101  76  93  73 /  10  30  80  40
SOUTH PADRE ISLAND      89  81  87  79 /  20  30  90  80
BAYVIEW/PORT ISABEL     93  77  90  75 /  20  30  90  70
&&
.BRO WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...None.
&&
$$
SHORT TERM...23
LONG TERM....23
AVIATION...60-BE

NWS BRO Office Area Forecast Discussion