Severe Thunderstorm Warning 36, NWS Brownsville, TX

Area Forecast Discussion
National Weather Service Brownsville TX
641 AM CDT Wed May 27 2026

...New AVIATION...

.KEY MESSAGES...
Updated at 640 AM CDT Wed May 27 2026

 - A Marginal to Slight Risk (levels 1 and 2 of 4) of isolated to
   scattered flash flooding from excessive and heavy rainfall is
   outlined for portions of Deep South Texas today.

 - Strong to isolated severe thunderstorms will continue into this
   morning and/or re-develop this afternoon. Primary threats are
   gusty winds, small hail, lightning, and locally heavy rain.

 - A moderate risk of rip currents continues through Thursday
   evening.

 - Minor to moderate heat risks (level 1 and 2 of 4) persist,
   peaking this weekend as dry conditions and clearer skies
   temporarily return.

&&

.DISCUSSION...
Issued at 1039 PM CDT Tue May 26 2026

And once again, we are now staring down the barrel of another
potential dark and stormy night here in deep south Texas. A deep and
negatively-tilted mid/upper level trough persists overnight across
northern and eastern TX, downstream of a strong trough/cut-off low
aloft digging southward over the western US. The combination of
Pacific (via southwesterly 700 mb flow) and Gulf (via lower level
southeasterly flow) moisture transport into the area of increased
forcing for ascension aloft has resulted in numerous severe
thunderstorms across western, central and southern Texas today
and this evening, with the southernmost portion of activity
currently producing a squall line extending south-southwestward
from just east of San Antonio on down to Webb and Duval counties,
just north of the Northern Ranchlands, generally moving due east.
Meanwhile, overcast skies loom over our region along with dry
conditions. The latest SPC Mesoanaylsis indicates 7.0-7.5 C/km
mid-level lapse rates and 35-45+ kt bulk shear across most of the
region as well as SBCAPE and MUCAPE values of 3,000-4,000 J/kg
(highest along/west of US-281) in addition to 500 mb analysis
showing the best upper level flow divergence across the Northern
Ranchlands, all of which is setting the stage for strong to severe
thunderstorms anticipated over the coming hours.

The HRRR continues to be more or less the best in accurately
initializing the latest regional conditions/radar and this evening's
00Z run indicates the area of developing convection over the Sierra
Madre/northwest of Zapata County to intensify and lengthen
southward, bringing the possibility of strong to scattered severe
thunderstorms, potentially along another squall line, eastward into
Zapata, Starr, Jim Hogg, Brooks and Kenedy counties late tonight,
where there is a Severe Thunderstorm Watch effective until 6 AM
Wednesday morning. The primary threats across this area continue
to be damaging winds of 58-75 mph and large to very large (1-2
inch) hail. Although Hidalgo, Cameron and Willacy counties are not
part of this watch due to less instability, conditions are still
supportive for strong to isolated severe thunderstorms, still
capable of producing strong to isolated damaging winds and small
to isolated large hail. Additionally, as PWATs could surge to as
high 2.0-2.30 in. overnight, these storms are likely to be
efficient rainfall producers with the capability of easily
producing 1-3+ inches where thunderstorms move slowly or train.
Therefore, WPC maintains a Slight Risk of scattered flash flooding
from excessive and heavy rainfall over the northern portions of
Zapata, Jim Hogg and Brooks counties as well as a Marginal Risk
for isolated flash flooding to as far south as southeastern Starr,
northwestern Hidalgo and northwestern Kenedy counties.

Whatever is left of the convective activity by Wednesday morning
should continue to move eastward and be mostly over the Gulf,
possibly by mid-morning, followed by a low to medium (30-60%)
chance of showers and thunderstorms in the afternoon and early
evening hours. However, due to run-to-run model inconsistency in
timing and convective mode(s), it is less certain for the prospects
of severe thunderstorms either continuing in the morning and/or
redeveloping in the afternoon. Yet, these aspects should gain more
confidence overnight tonight as the convection unfolds. Still,
high moisture content leads to a Marginal Risk of isolated flash
flooding mainly along/east of US-281, as far west as the far
eastern portions of Jim Hogg County and northern/eastern half of
Hidalgo County.

Ridging resumes behind the departing trough Wednesday night with a
dry stretch ensuing into the weekend, when troughing over Mexico and
the Desert Southwest begin to bring some more daily chances of
unsettled weather, possibly beginning Saturday night. Chances
remain low to medium (20-40%) at this time, though could become
more widespread and persistent by early next week.

High temperatures in the low/mid 90s, possibly upper 80s further
north, continue through most of the next 7 days along with maximum
afternoon heat indices ranging within a few degrees from 100-105 F.
Mainly minor heat risks can be expected across most of the region
each day though more urban areas of the RGV could experience
moderate. As moisture and heat build again from southeasterly winds
and increased sunshine late this week and into this weekend, a
moderate risk could become more widespread across the RGV Friday
into Saturday and across the rest of the region on Sunday before
reducing to mostly minor early next week as cloud cover increases.
Heat indices up to 110 F are possible within the moderate heat
risks.

A moderate risk of rip currents continues through Thursday evening.

&&

.AVIATION...
(12Z TAFS)
Issued at 640 AM CDT Wed May 27 2026

MVFR ceilings and southerly to southeasterly winds around 10 to
15 knots are being observed across the TAF sites this morning.
Meanwhile, a complex of showers and strong thunderstorms continue
to translate across portions of the Northern Ranchlands and mid
Texas coast. High res guidance indicates this activity should
spread further south towards the TAF sites by mid morning, and
exit the region by early to mid afternoon. Main threats with any
thunderstorms will be gusty winds, small hail, reduced ceilings
and/or visibility, lightning, and locally heavy rain. Brief wind
shifts can also be expected within any strong thunderstorms.
Conditions should improve later this afternoon, although
intermittent periods of MVFR ceilings cannot be ruled out.

&&

.MARINE...
Issued at 1039 PM CDT Tue May 26 2026

Small Craft Exercise Caution headlines, resulting from moderate to
fresh winds and moderate (3-5 ft) seas are likely to continue
through tonight before easing to mainly gentle to moderate easterly
to southeasterly winds and slight to moderate (2-4 ft) seas for the
remainder of the next 7 days. Chances of rain gradually increase
throughout tonight to as much a medium (40-60%) chance Wednesday
morning and gradually diminish to around 15% or less from Thursday
into this weekend. Low to medium chances of rain return either late
this weekend or early next week.

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             90  77  92  77 /  40  20  20   0
HARLINGEN               90  74  91  74 /  50  20  10   0
MCALLEN                 92  77  93  76 /  40  10  20   0
RIO GRANDE CITY         92  74  93  75 /  40  20  10   0
SOUTH PADRE ISLAND      85  80  85  80 /  40  20  10   0
BAYVIEW/PORT ISABEL     88  77  89  77 /  40  20  10   0

&&

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

SHORT TERM...65
LONG TERM....65
AVIATION...22-Garcia

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Special Weather Statement
National Weather Service Brownsville TX
645 AM CDT Wed May 27 2026

TXZ249-250-271230-
Brooks TX-Jim Hogg TX-
645 AM CDT Wed May 27 2026

...STRONG THUNDERSTORMS WILL IMPACT CENTRAL JIM HOGG AND BROOKS
COUNTIES THROUGH 730 AM CDT...

At 645 AM CDT, Doppler radar was tracking a cluster of strong
thunderstorms 14 miles northeast of San Rafael Ranch Airport, or 15
miles northeast of Agua Nueva, moving northeast at 30 mph.

HAZARD...Wind gusts up to 40 mph and pea size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor hail damage to vegetation is
         possible.

Locations impacted include...
Falfurrias, Hebbronville, Gruy Stadium, La Colonia Park, Airport Road
Addition, South Fork Estates, Falfurrias Junior High School, Las
Lomitas, Pleasant Park, and El Coyote Ranch Airport.

This includes US Highway 281 between mile markers 708 and 728.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

A Severe Thunderstorm Watch remains in effect until 800 AM CDT for
Deep South Texas.

&&

LAT...LON 2734 9855 2734 9852 2727 9852 2726 9799
      2678 9822 2678 9837 2727 9896 2727 9880
      2735 9879 2736 9863 2734 9862 2734 9859
      2736 9859 2736 9855
TIME...MOT...LOC 1145Z 204DEG 41KT 2700 9838

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPH

23-ATE

Special Weather Statement
National Weather Service Brownsville TX
648 AM CDT Wed May 27 2026

TXZ248-271230-
Zapata TX-
648 AM CDT Wed May 27 2026

...A STRONG THUNDERSTORM WILL IMPACT NORTHERN ZAPATA COUNTY THROUGH
730 AM CDT...

At 647 AM CDT, Doppler radar was tracking a strong thunderstorm 10
miles southeast of El Cenizo, or 10 miles north of San Ygnacio,
moving northeast at 35 mph.

HAZARD...Wind gusts up to 40 mph and pea size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor hail damage to vegetation is
         possible.

Locations impacted include...
San Ygnacio.

This includes US Highway 83 between mile markers 738 and 762.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

A Severe Thunderstorm Watch remains in effect until 800 AM CDT for
Deep South Texas.

&&

LAT...LON 2709 9943 2711 9944 2713 9943 2715 9944
      2718 9943 2727 9945 2732 9937 2727 9933
      2727 9898 2692 9932 2694 9939 2696 9939
      2698 9938 2702 9942 2701 9943 2702 9945
      2706 9945
TIME...MOT...LOC 1147Z 222DEG 33KT 2720 9944

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPH

23-ATE

Special Weather Statement
National Weather Service Brownsville TX
744 AM CDT Wed May 27 2026

TXZ251-353-271315-
Northern Hidalgo TX-Inland Kenedy TX-
744 AM CDT Wed May 27 2026

...A STRONG THUNDERSTORM WILL IMPACT SOUTHWESTERN KENEDY AND
NORTHEASTERN HIDALGO COUNTIES THROUGH 815 AM CDT...

At 743 AM CDT, Doppler radar was tracking a strong thunderstorm near
San Manuel, moving north at 35 mph.

HAZARD...Wind gusts up to 40 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
San Manuel, Linn, and Hargill Reservoir.

This includes US Highway 281 between mile markers 748 and 760.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

A Severe Thunderstorm Watch remains in effect until 800 AM CDT for
Deep South Texas.

&&

LAT...LON 2670 9783 2660 9790 2661 9796 2655 9797
      2653 9796 2654 9798 2649 9799 2649 9800
      2646 9800 2653 9818 2677 9809
TIME...MOT...LOC 1243Z 202DEG 30KT 2658 9806

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPH

55-MM