682
FXUS64 KBRO 171743
AFDBRO

Area Forecast Discussion
National Weather Service Brownsville TX
1243 PM CDT Fri Oct 17 2025

...New DISCUSSION, AVIATION, MARINE, CLIMATE...

.KEY MESSAGES...
Updated at 1238 PM CDT Fri Oct 17 2025

* "Endless Summer" heat dominates through next Friday and beyond,
  with minor to moderate daytime heat risk impacting those with
  limited access to air conditioning.

* Moderate rip currents will continue through the weekend and into
  early next week, masking danger from warm surf and inviting
  waves.

&&

.DISCUSSION...
Issued at 1238 PM CDT Fri Oct 17 2025

The story of "Hot-tober" continues across the Rio Grande Valley/Deep
South Texas ranchlands for at least the next week, as 500 mb
westerly flow aloft with broad "flat" ridging over the southern Gulf
through Saturday builds/develops northwest into Texas and northern
Mexico by Sunday, behind a quick-moving short wave that scoots
across north Texas/Oklahoma on Saturday. Once the 500 mb ridge, or
"heat dome", becomes established later Sunday it holds forth across
south Texas and northeast Mexico through next weekend.

In terms of sensible weather, the daytime heat is the story through
the period. Consensus continues for a limited impact windshift from
the southeast to the north, then northeast on Sunday, with no
discernible impact for areas away from the coast in terms of
temperature or humidity. Otherwise, the prevailing southeast to
south flow tonight through Saturday night, and again Monday through
next Friday, will be more notable in overnight/early morning
temperatures, which will rise from the relatively comfortable 60s-70
for many days this week to the more muggy upper 60s (ranchlands) to
the low-mid 70s in urban and coastal areas of the RGV.  Daytime
temperatures will continue to average 5 to 10 degrees above second-
to-last week of October averages (mid to upper 80s) while overnight
temperatures about 3 to 7 degrees above (60 to 66 is average).

Finally...the weakening easterly swell into Saturday could reduce
rip currents a smidge, but the expected wind shift and a period of
longer northeast to easterly long-fetch later Sunday and especially
Monday will bring solid moderate rips back into play, and we could
edge toward high, especially if combined seas end up a foot or two
higher than forecast (see Marine discussion below).  Moderate rips
and surf should continue through the week, as  gradually improve
later Tuesday and Wednesday with a 1022-1026 surface high pressure
center(s) across the southwest U.S. maintain a sufficient fetch
and at least a 6-7 second swell period to support them.

As for "King" tide situations - the increased fetch and swell may
shrink the beach a little during high tides next week (mostly in
the afternoon next week), but the astronomical values are on the
lower side so not expecting any significant run-up at this point.

&&

.AVIATION...
(18Z TAFS)
Issued at 1238 PM CDT Fri Oct 17 2025

VFR is the rule with mainly clear skies outside of few-scattered
afternoon and late morning fair weather cumulus.  Winds will be
light to briefly moderate from the east-southeast this afternoon
(sea breeze help), then should be just enough (3-6 knots) from the
southeast overnight to preclude any fog as dewpoints rise a bit.
Will need to keep an eye on Harlingen/Valley just in case, but won`t
mention now.

Other than thermals and slightly gusty east/southeast sea breeze
enhanced conditions later this afternoon, great takeoff/landing
weather for the period.

&&

.MARINE...
Issued at 1238 PM CDT Fri Oct 17 2025

Through early Monday: Modest south to southeast flow develops
tonight and continues through pre-dawn Sunday, with waves in check
(2 to 3 feet) and swell period (east-southeast direction) at 4-5
seconds. That changes a bit Sunday behind the wind shift, with winds
swinging around to north/northeast by afternoon and picking up a bit
(10-15 knots) which, given the longer fetch, should quickly push
period back to 7 seconds.  Edited the data to jump on this change
for late afternoon.  Northeast, then east, winds and a continued 7
second east-northeast swell period will continue into Monday.
Current blended wave model data holds combined seas at 3 feet, but
there`s plenty of opportunity to see average heights rise to 4 feet,
perhaps nearing 5 feet, Sunday evening into Monday morning. Will
continue to track trends and explain this in the synopsis.

Early Monday through Wednesday Night: Light to moderate east-
southeast to southeast flow returns later Monday and continues
through early Wednesday, with some potential for a slight shift from
the east-northeast later Wednesday.  One thing to watch will be the
strength of the easterly fetch Wednesday and beyond. ECMWF increases
the eastern Gulf gradient between southeast U.S. classic October
surface ridge and a stronger Caribbean "gyre" (low) which would
build back swell and combined seas and send them toward the western
Gulf. Still time to evaluate; for now, no Small Craft headlines
anticipated during this forecast period.

&&

.CLIMATE...
Issued at 1238 PM CDT Fri Oct 17 2025

It`s been a fairly "Hot-tober" in 2025. While not at or near the
very top, rankings through the 16th are in range...and with the
forecast through at least next Friday keeping daily day/night
averages in the 4 to 7 degree above range (based on 1991-2020 data),
October may rise into the top five for more locations and stay there
through the end of the month. Through the 16th:

Brownsville (since 1878): 4th hottest (82.6 degrees)
Harlingen (since 1912):  15th hottest (80.4)
McAllen (since 1941):  6th hottest (83.6)
Rio Grande City (most data since 1928): 22nd hottest (80.3)
Raymondville (since 1913): 11th hottest (80.6)
Port Mansfield (since 1958):  10th hottest (79.4)

For the calendar year so far (289 days...leap years removed), rankings
are similar.  Given the expected above to potentially much above-average
temperatures through the remainder of the year, another top-five or
top ten warmest year is becoming more likely:

Brownsville:  6th warmest (78.9 degrees)
Harlingen:  26th warmest (77.2)...missing 2024 as a comparison
McAllen: 7th warmest (80.2)
Rio Grande City:  8th warmest (79.1)
Raymondville: 8th warmest (77.7)
Port Mansfield:  15th warmest (75.7)

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             72  93  75  93 /   0   0   0  10
HARLINGEN               68  94  71  94 /   0   0   0  10
MCALLEN                 72  98  75  98 /   0   0   0  10
RIO GRANDE CITY         69  98  71  98 /   0   0   0  10
SOUTH PADRE ISLAND      78  87  79  87 /   0   0   0  10
BAYVIEW/PORT ISABEL     72  89  74  89 /   0   0   0  10

&&

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

$$

SHORT TERM...52-Goldsmith
LONG TERM....52-Goldsmith
AVIATION...52-Goldsmith
CLIMATE...52/Goldsmith