461
FXUS64 KBRO 110519 AAA
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
1219 AM CDT Mon May 11 2026

...New AVIATION...

.KEY MESSAGES...
Updated at 1216 AM CDT Mon May 11 2026

Key Messages:

* Keeping an eye on potential severe weather, mainly damaging winds,
for the Rio Grande Plains and Brush Country (Zapata, northern Starr,
Jim Hogg) after midnight and before daybreak Monday

* Conditions should dry out quickly later Monday morning and
continue through much of the work week, with slightly below
average temperatures for mid-May and only a minor heat risk

* After some unsettled winds and surf Monday, favorable marine,
coastal, and beach conditions dominate the rest of the work week

* Heat risk returns to moderate or higher levels by next weekend

&&

.DISCUSSION...
Issued at 1054 PM CDT Sun May 10 2026

Rest of tonight through early Monday:  The greatest potential for
hazardous weather during the seven-day period exists right off the
bat. After early evening isolated strong to severe storms in the
upper Valley Sunday, conditions have quieted, for now. However, an
expected squall line has formed, and as of 1030 PM extended from San
Antonio through just south of Eagle Pass.  A combination of CAMs
models and incoming short-range models suggest that sensible
overnight weather will feature highest rain chances - and severe
weather threat in the form of damaging squall-line type winds -
across the Rio Grande Plains/Brush Country areas of Zapata, Jim
Hogg, and northern Starr...perhaps extending into Brooks and Kenedy,
arriving between 1 and 3 AM. For the rest of the area, including the
populated Rio Grande Valley, increasing overnight stability and
capping favor weakening/dissipating threat as the line...pushed by a
weak front...moves southeast between 3 and 6 AM. Storm Prediction
Center also agreed with this, as their 730 PM update alluded to
weakening of the line into the increasingly stable/capped air.

All this said...surface air ahead of the boundary/line is quite warm
and sticky, and the 00Z sounding was conditionally unstable with
most unstable CAPE over 4K J/kg. So...if for some reason, a more
robust squall line accelerates at pace late tonight (and a little
earlier than expected), the populated RGV could see more pronounced
activity just before daybreak. For now, that probability likely sits
at 10% or less, so will not highlight.

As for rainfall...WPC has these areas outlooked for isolated flash
flooding (marginal - level 1 of 4) but given the expected movement
of any stronger cells, more nuisance flooding would be more the
case.

The recently arrived blended suite of near-term forecast data
matches this thinking, so no changes are planned.

Rest of Monday:  Winds shift to the north/northeast and drier, more
stable air filters in steadily. Rain chances should quickly end from
northwest to southeast, but remnant clouds behind the front in
north/northeast flow will keep temperatures several degrees below
average (mainly 80s).

Monday Night through Thursday:  If you have some time to spare, this
is true "bonus weather" for the region, as we sit underneath the
front side of a modest (for mid May) 500 mb ridge and the back side
of fairly robust eastern U.S. troughing.  Dry air slides across most
of Texas Monday night and remains in place through Thursday, with
lowering humidity, generally light northeast to east winds, and
plenty of sunshine. May sun will bring afternoon highs into the
upper 80s to low 90s, about 2-4 degrees below average...while
mornings will dawn in the upper 60s to around 70 (mid 60s in
preferred cooler spots) - also, 2-4 degrees below.

Thursday Night through Sunday: The eastern trough weakens/pulls
away, and the 500 mb ridge that extended across all of Texas gets
flattened to northern Mexico. Troughing passing through the southern
Plains helps to bring surface troughing to west Texas, with the
resulring increase in south/southeast flow for the region beginning
Friday and dominating through the weekend. That ends the "bonus
weather" quickly, and returns sultry nights and hot/humid days to
the region. Moderate heat risk returns as apparent temperatures
build back into the 103-107 range Saturday and Sunday.

&&

.AVIATION...
(06Z TAFS)
Issued at 1216 AM CDT Mon May 11 2026

While a large majority of the TAF period could be in VFR
conditions, there is a large system of thunderstorms are will be
moving through the region during the overnight hours. Particularly
within the next few hours. This could bring either MVFR to IFR
conditions to the area. There is even a low chance of LIFR
visibilities due to heavy downpours as well. After the line of
storms moves through then a return to MVFR is expected, which by
the later part of the morning should go to VFR for the rest of the
period. Light northerly winds should persist through the period
outside of any thunderstorms.

&&

.MARINE...
Issued at 1054 PM CDT Sun May 10 2026

Rest of Tonight through early Monday:  The key concern will be
impact from whatever remains of the south-central Texas
convection/squall line by early Monday.  Should the line hold
together, we could see a short period of gale-force gusts due to any
wake low/meso high developments, especially north of Port Mansfield.
Otherwise, the concern would be lightning and brief downpours.
Timing could line up with any early morning fishing trips, so
boaters may wish to postpone trips until whatever storms there are
no longer pose a threat.

Later Monday through Thursday: Freshening north/northeast winds will
briefly build seas toward 4 feet Monday afternoon before high
pressure ridge at the surface settles in for the remainder of this
period, allowing winds to diminish back to 5-10 knots (from the east-
northeast)and seas to become mainly slight (2-3 feet) with no
additional rainfall.

Thursday night through Friday night: As the ridge moves into the
eastern Gulf, southeast flow returns and gradually increases, with
perhaps caution level winds arriving later Friday into Friday night.

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             87  74  87  72 /  30   0   0   0
HARLINGEN               86  70  86  68 /  30   0   0   0
MCALLEN                 87  73  88  72 /  30   0   0   0
RIO GRANDE CITY         86  72  87  71 /  20  10   0   0
SOUTH PADRE ISLAND      82  77  81  76 /  30   0   0   0
BAYVIEW/PORT ISABEL     85  74  85  72 /  30   0   0   0

&&

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

$$

SHORT TERM...52
LONG TERM....52
AVIATION...64-Katz