785
FXUS64 KBRO 060537 AAA
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
1237 AM CDT Fri Jun 6 2025

...New AVIATION...

.SHORT TERM...
(Tonight through Saturday night)
Issued at 1035 PM CDT Thu Jun 5 2025

A quasistationary 593 Dm ridge remains in place across northern
Mexico into the western Gulf waters through Saturday night. This is
about 2 standard deviations above normal for all the major ensemble
guidance. Therefore, confidence is high (70 to 80 percent) in
moderate to even pockets of major heat risk concerns heading into
the weekend. Subsidence inversion means largely rain-free conditions
except for isolated streamer showers over the Gulf waters and
immediate coast. Persistent surface low pressure across west Texas
and 1016mb surface high over the eastern Gulf waters mean continued
southeasterly winds. Forecast soundings show mixing up to 925mb, and
with a 25-30 kt southeasterly low-level jet (LLJ), expect gusty
conditions Friday afternoon with 25-30 mph gusts at times. Even
higher gusts are possible with 30-35 mph on Saturday. Isolated 35-40
mph gusts are not out of the question Saturday into Saturday night
for areas west of I-69C/US-281 as the 925-850mb LLJ becomes more
south-southeasterly oriented and strengthens to 30-35 kt and mixing
deepens. Oppressive heat will also build and become more widespread
heading into Saturday, although heat indices (which is a function of
ambient air temperature and dew point temperature) should remain
generally between 100-110 degrees on both Friday and Saturday. This
is because while areas west of I-69C see temperatures top out in 96-
103 range, dew point temperatures would be somewhat more tolerable
in the 63-69 range. Areas east of I-69C/US-281 and especially along
the I-69E corridor see air temperature in the 90-97 range (except 85-
89 on SPI) but dew points in the 68-75 range.

We will likely need a Special Weather Statement (SPS) for heat index
values topping out in the 105 to 110 range this (Friday) afternoon
and on Saturday afternoon. Depending on model trends and how much we
cool off Friday night, a Heat Advisory might even be needed for
parts of the area on Saturday for heat index values exceeding 111.
Regardless of whether it is a SPS or Heat Advisory, widespread
moderate (level 2 of 4) heat risk is likely, with pockets of major
(level 3 of 4) heat risk. Please take the heat seriously especially
for those with outdoor plans, including proper hydration and access
to cooling measures.

On a side note, Saharan dust originating from Africa could make for
vibrant sunrises and sunsets through the weekend, although better
probabilities are across the eastern Gulf. No deterioration in air
quality is expected.

&&

.LONG TERM...
(Sunday through next Friday)
Issued at 1035 PM CDT Thu Jun 5 2025

It will still be uncomfortably to oppressively hot heading into
Sunday. 590+ Dm ridge remains in control over our area but should be
shunted southwestward into Mexico as we head into the start of the
new work week. This is consistent with the upper level trough over
the central and eastern U.S. becoming more amplified. Major heat
risk (level 3 of 4) becomes widespread by Sunday into Monday due to
the cumulative effect of the prolonged heat and lack of nocturnal
cooling. The latter is especially true for areas along and east of I-
69E across the densely populated urban corridors of Cameron and
Hidalgo counties, where the oppressive dew points in the mid to
upper 70s mean that overnight lows will struggle to fall below 80
degrees. Further west across the mid and upper Valley, lower dew
points in the upper 50s to mid 60s will mitigate the higher air
temperatures, which are expected top out in the 102 to 107 range.
Expect maximum heat index values of 105 to 111 Sunday into Monday.
While not quite reaching Heat Advisory criteria, once again, the
cumulative effects of the prolonged heat and lack of nocturnal
cooling mean more widespread major heat risk impacts.

Forecast uncertainty increases as we head into Tuesday and
Wednesday. Models diverge in how quickly the upper level ridge
breaks down and if the embedded shortwave energy can lead to any
organized convection. Shower and thunderstorm chances begin to
increase late Tuesday into Wednesday as a cold front tries to push
southward but may end up stalling north of our CWA. Given the
uncertainty for the mid to latter half of the week, have largely
stuck with the blended guidance. But it is fair to say that
confidence is medium to medium high (50-70 percent) that the weather
pattern is going to get more unsettled by mid week, although it
remains to be seen (10-30 percent confidence) whether we will get
garden variety showers or more organized convection.

&&

.AVIATION...
(06Z TAFS)
Issued at 1234 AM CDT Fri Jun 6 2025

MVFR to VFR will be the rule at the aerodromes through the next 24
hours. Light winds overnight will become breezy on Friday before
diminishing around sunset. Partly cloudy and rain-free skies are
also anticipated.

&&

.MARINE...
Issued at 1035 PM CDT Thu Jun 5 2025

Generally favorable marine conditions will prevail with light to
moderate southeasterly winds and low to moderate seas. Small Craft
Exercise Caution conditions are likely over the weekend into early
next week along the Laguna Madre and nearshore Gulf waters. Mainly
dry and warm conditions are expected over the weekend except for
isolated showers over the Gulf waters. Weather pattern becomes more
unsettled heading into middle of next week with 30-50 percent chance
for showers and thunderstorms as a frontal boundary approaches but
stalls north of our region.

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             80  94  81  94 /   0   0   0   0
HARLINGEN               78  96  78  97 /   0   0   0   0
MCALLEN                 80 100  81 101 /   0   0   0   0
RIO GRANDE CITY         79 101  78 102 /   0   0   0   0
SOUTH PADRE ISLAND      81  88  82  88 /   0   0   0   0
BAYVIEW/PORT ISABEL     80  92  80  92 /   0   0   0   0

&&

.BRO WATCHES/WARNINGS/ADVISORIES...None.

&&

$$