Wind Advisory 6, NWS Brownsville, TX

142 
WWUS74 KBRO 181838
NPWBRO

URGENT - WEATHER MESSAGE
National Weather Service Brownsville TX
138 PM CDT Mon May 18 2026

TXZ254-255-351-354-355-451-454-455-181945-
/O.CAN.KBRO.WI.Y.0006.000000T0000Z-260518T2100Z/
Inland Willacy-Inland Cameron-Coastal Kenedy-Coastal Willacy-
Coastal Cameron-Kenedy Island-Willacy Island-Cameron Island-
Including the cities of Harlingen, Raymondville, Brownsville, Boca
Chica Beach, Laguna Vista, South Padre Island, Port Mansfield, and
Port Isabel
138 PM CDT Mon May 18 2026

...WIND ADVISORY IS CANCELLED...

The threat has ended.

$$

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
608 AM CDT Mon May 18 2026

...New AVIATION...

.KEY MESSAGES...
Updated at 605 AM CDT Mon May 18 2026

Key Messages:

* Daily or near daily chances for showers and thunderstorms is
  expected through the upcoming workweek and possibly through the
  end of May as a major shift in the weather pattern takes shape.

* Strong to severe thunderstorms along with heavy rainfall and
  localized flooding is possible through the upcoming workweek.

* Hot and humid conditions will take place through Tuesday; maximum
  heat indices between 105-111F degrees will result in widespread
  Moderate (Level 2 of 4) to Major (Level 3 of 4) Heat Risk through
  Tuesday.

* A Small Craft Advisory has been extended till 9 AM CDT Tuesday; a
  High Risk for Rip Currents may need to be expected till Tuesday as
  well.

&&

.UPDATE...
Issued at 1228 AM CDT Mon May 18 2026

Collaborated higher POPs through Tuesday afternoon with our
neighboring office, given showers and thunderstorms actively on
radar across the brush country and upper valley. Leaned into more
of a diurnal cycle from west to east into Monday morning and
Tuesday morning.

&&

.DISCUSSION...
Issued at 1028 PM CDT Sun May 17 2026

Building heat with Moderate (Level 2 of 4) to Major (Level 3 of 4)
Heat Risk through Tuesday (possibly into Wednesday), and an
increasingly unsettled weather pattern punctuating a significant
pattern change from dry to wet are the two main weather headlines
through the forecast period. We'll first begin talking about the
unsettled weather pattern followed by the building heat through
midweek.

Global computer and AI/ML models/ensembles continues to advertise a
significant pattern change from dry to wet beginning this week. A
split-flow 500 mb pattern featuring what will become an increasingly
active and persistent southwest flow aloft sub-tropical jet or
southern branch jet stream is in place. This will serve as a
conduit for multiple impulses/perturbations tracking over the
region over the next several days. Later in the week through next
weekend, there are sings that mid-upper troughing along with
multiple impulses/perturbations will undercut high
pressure/ridging aloft. This large-scale setup will help to yield
incessant day-to-day or near day-to-day chances for showers and
thunderstorms through at least next week and maybe through the
remainder of May.

Closer to the sfc, a frontal boundary will sag southward across
the U.S. before stalling and meandering to our north across the
southern Plains. More than normal favorable jet dynamics will be
in place through next week. Additionally, southerly flow near the
sfc will yield a pool of deep tropical moisture helping to
increase the atmospheric water content over the region through the
week ahead. This is justified with sample maximum precipitable
water (PWAT) values between 1.80-2.50 inches, some 1-3 STDEVs
above normal and above the 90th percentile of sounding climatology
for mid to late May. Furthermore, high instability values will be
present through this week with steep mid level lapse rates
between 6.5-8.0 C/km, SBCAPE values between 2,000-4,000 J/kg,
MLCAPE values between 1,000- 2,000 J/kg, a moderately to very
unstable atmosphere with Showalter values ranging between -2 and
-6.

The combination of a favorable mid-upper level 500 mb steering
pattern, favorable jet stream dynamics, high atmospheric moisture
content, and high instability will support a noticeable change to a
wetter/active weather pattern this week and possibly beyond.
Strong to severe thunderstorms are possible given the atmospheric
and forcing ingredients highlighted above. The Storm Prediction
Center (SPC) has highlighted the northwestern half of our area
under a Marginal Risk (Level 1 of 5) for severe thunderstorms on
Tuesday. This includes all of Zapata and Jim Hogg Counties, and
most of Brooks and Starr Counties in it's latest SWODY3.

Given the high atmospheric moisture content available, heavy
rainfall and instances of flooding is possible through the week,
especially later in the week. This is especially true for slow
moving thunderstorms that repeatedly track over the same areas.
The Weather Prediction Center (WPC) has placed the entire forecast
area or all of Deep South Texas under a Marginal Risk (Level 1 of
4) for Excessive Rainfall in it's Day 4 (Wednesday) and Day 5
(Thursday) ERO.

Most of the convection through next week is anticipated to initiate
off the Sierra Madre before possibly rolling off the front range
and translating east-northeastward into our CWA. So far, for
Monday night, low (20%) chance PoPs are forecasted generally along
the Rio Grande Valley. Tuesday night, rain chances increase with
low-medium (30-40%) PoPs for showers and thunderstorms.
Wednesday-Wednesday night, there is a low-medium (20-40%) chances
for showers and thunderstorms. Thursday will feature medium
(30-60%) chances. By Thursday night, rain chances increase with
widespread categorical or medium-high (50-80%) chances. Friday
through Saturday, there remain medium (30-60%) chances across Deep
South Texas. Finally, Saturday night through next Monday, there
exists medium (30-50%) chances. Overall, there generally is a
30-60% chance for showers and thunderstorms through the forecast
period with Thursday night yielding the greatest chances between
50-80%.

The other news will be the heat! Global forecast models/ensembles
continue to depict a strengthening 588-591 dam sub-tropical heat
ridge developing over the region early next week. This feature will
result in hotter than normal temperatures through Tuesday, and maybe
even extending into Wednesday. Forecast high temperatures for
Monday and Tuesday are expected to be in the mid 90s to lower 100s
with the hottest temps west of IH-69C/US-281. Dewpoints in the
mid 70s will result in max heat indices or apparent temperature
values climbing to between 105-111F degrees on both Monday and
Tuesday. These values will result in Moderate (Level 2 of 4) to
Major (Level 3 of 4) Heat Risk both days. Cloud over will be a
factor in these temperatures being realized.

By Wednesday, the aforementioned heat ridge relaxes which should result
in a slightly cooler day. Shower and thunderstorm chances Tuesday
night into Wednesday as well as cloud cover could also play a
role in the slightly lower temperatures from Monday and Tuesday.
Nonetheless, it will be another warmer than normal day with high
temperatures in the low to mid 90s. With heat indices ranging
between 100-108F degrees, Heat Risk scores will be mainly Moderate
(Level 2 of 4) over the region on Wednesday.

Thursday through next Sunday, high temperatures will range
between the upper 80s to lower 90s. This largely will be due to
the shower and thunderstorm chances during this timeframe. Tonight
through Tuesday night, overnight lows are progged to be in the
upper 70s to lower 80s. Wednesday night through next Sunday night,
overnight lows are expected to be mainly in the 70s.

&&

.AVIATION...
(12Z TAFS)
Issued at 605 AM CDT Mon May 18 2026

VFR and MVFR conditions are expected to improve this morning to
all VFR with breezy to gusty southeasterly winds. MVFR ceilings
likely return this evening through tonight. Isolated thunderstorms
may develop west of MFE tonight and work towards the RGV
aerodromes into Tuesday morning. Confidence is too low to include
in this TAF package.

&&

.MARINE...
Issued at 1028 PM CDT Sun May 17 2026

A Small Craft Advisory has been extended till Tuesday morning due to
continued breezy southeasterly winds and elevated wave heights.
Outside of the threat for showers and thunderstorms, Tuesday through
Wednesday, adverse (Small Craft Exercise Caution) conditions are
possible. Again, outside of the threat for showers and
thunderstorms Wednesday night through next Sunday, marine
conditions are expected to improve with moderate seas and low to
moderate winds.

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             95  81  94  81 /  20  20  20  20
HARLINGEN               96  79  95  79 /  20  20  20  40
MCALLEN                 97  81  97  79 /  20  30  20  30
RIO GRANDE CITY         99  79  98  78 /  20  30  20  40
SOUTH PADRE ISLAND      86  81  86  81 /  20  20  20  20
BAYVIEW/PORT ISABEL     93  80  92  80 /  20  20  20  30

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...High Rip Current Risk through Tuesday evening for TXZ451-454-455.

GM...Small Craft Advisory until 9 AM CDT Tuesday for GMZ130-132-135-
     150-155-170-175.

&&

SHORT TERM...23-Evbuoma
LONG TERM....23-Evbuoma
AVIATION...56-Hallman