365
FXUS64 KBRO 121148 AAA
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
648 AM CDT Wed Mar 12 2025

...New AVIATION...

.SHORT TERM...
(Today through Thursday)
Issued at 251 AM CDT Wed Mar 12 2025

An upper level trough moving across the Central Plains today will
drive a weak cold font south into northwestern portions of the CWA
this afternoon. The cold front is expected to wash out as it moves
into the CWA, having minimal impact on high temperatures though it
will bring a drop in dewpoints across Zapata and portions of Starr
and Jim Hogg counties. High temperatures are expected to range from
the low 90s across the eastern counties to the upper 90s out west
today.

Winds are expected to become light and variable overnight, which
combined with clear skies will allow for efficient radiative
cooling.  As such, overnight low temperatures are expected to fall
to the upper 50s to mid 60s. Gusty southeasterly winds are expected
to return Thursday afternoon, with high temperatures returning to
the low to mid 90s.

Afternoon minimum RH values are expected to range from the mid teens
out west, to the 20s across central portions of the CWA, to around
35-40% along the coast today.  In spite of the low RH values, fire
weather concerns remain somewhat limited today, due to 20 ft winds
remaining below 15 mph across most of the CWA. A similar story is
expected Thursday, with even lower RH values (10-20%), but 20 ft
winds remaining below 15 mph.

&&

.LONG TERM...
(Thursday night through Tuesday)
Issued at 251 AM CDT Wed Mar 12 2025

A 500mb trough deepens across most of the central CONUS before
pushing east, followed by a ridge and the next trough by mid next
week. This will generally maintain very dry westerly flow across
Deep South Texas through the long term period. At the surface,
expect southerly winds turning southwesterly on Friday as a
dryline works eastward, setting up a heat spike. A dry front
follows on Saturday, with high pressure building into early next
week.

Have bumped up high temperatures on Friday due to moderate
downsloping, mixing in NBM25 and ECMWF guidance, which still may
not be warm enough. Triple digit heat will overtake most of the
RGV and potentially set multiple record highs. Above normal
temperatures generally persist through the remainder of the long
term, though not nearly as warm as Friday afternoon.

Of more concern this weekend into early next week are fire
weather conditions. ERC values across Deep South Texas rapidly
approach the 90th percentile by Friday, then launch near or above
the 97th percentile and record high values this weekend into early
next week. Historically, there is a noticeable increase in
wildfire activity when the ERC values reach these heights.
Unfortunately, RH values drop into the teens and single digits
each afternoon Friday through Sunday, with only gradual
improvements Monday into Tuesday. Fuels remain cured and dry to
critically dry.

The only limiting factor through this stretch is 20 foot wind
speeds falling short or just short of Red Flag criteria. In these
conditions, Fire Danger Statements and Red Flag Warnings may still be
needed, regardless of 20 foot wind speed criteria, for the
protection of life and property this weekend into early next week.
Fire Weather Watches may be issued as early as tomorrow. Stay
tuned and do whatever necessary to avoid open flames or sparks.
Additional dry frontal boundaries are on the horizon just beyond
the long term, potentially continuing fire weather concerns into
late March.

&&

.AVIATION...
(12Z TAFS)
Issued at 635 AM CDT Wed Mar 12 2025

VFR conditions are expected to continue through the day today,
with IFR to LIFR developing early Thursday morning. Skies are
expected to remain mostly clear through much of the TAF period,
though some low stratus could develop shortly before sunrise
Thursday morning. Fog development is looking increasingly likely
early Thursday morning, as clear skies and light and variable
winds will support efficient radiative cooling overnight. BRO and
HRL look to have the best probability of visibility reaching LIFR
levels, while visibility at MFE may only reach IFR levels.


&&

.MARINE...
Issued at 251 AM CDT Wed Mar 12 2025

Today through Thursday...Adverse marine conditions are expected to
briefly develop this afternoon as winds along the Lower Texas Coast
as winds increase to 15-20 kts. Small Craft Should Exercise Cation
headlines will likely be needed this afternoon. Winds are expected
to decrease overnight, with favorable conditions continuing through
the remainder of the short term. Seas are expected to remain light
to moderate through the period.

Thursday Night through Tuesday...Southerly winds prevail through
Friday across coastal waters, before a weak frontal boundary
brings northerly winds over the weekend. Early next week, as low
pressure deepens into the Plains, expect moderate to strong
southerly winds building seas. SCEC conditions are likely
offshore Friday into Saturday and again Tuesday.

&&

.FIRE WEATHER...
Issued at 251 AM CDT Wed Mar 12 2025

Friday through Tuesday...Energy Release Component values across
Deep South Texas rapidly approach the 90th percentile by Friday,
then launch near or above the 97th percentile and record high
values this weekend into early next week. Relative humidity values
drop into the teens and single digits each afternoon Friday
through Sunday, with only gradual improvements Monday into
Tuesday. Fuels remain cured and dry to critically dry. The only
limiting factor through this stretch is 20 foot wind speeds
falling short or just short of Red Flag criteria through Monday.
In these conditions, Fire Danger Statements and Red Flag Warnings
may still be needed, regardless of 20 foot wind speed criteria,
for the protection of life and property this weekend into early
next week. Fire Weather Watches may be issued as early as
tomorrow. Stay tuned and do whatever necessary to avoid open
flames or sparks. Additional dry frontal boundaries are on the
horizon just beyond the long term, potentially continuing fire
weather concerns into late March.

&&

.CLIMATE...
Issued at 251 AM CDT Wed Mar 12 2025

High temperatures on Friday may approach or topple record highs
for multiple locations in the Rio Grande Valley due to
southwesterly downsloping winds. The daily record high in
Brownsville for March 14 is 93 degrees. The daily record high in
Harlingen for March 14 is 96 degrees. The daily record high in
McAllen for March 14 is 104 degrees. The current high temperature
forecasts for all three are 96, 99, and 102 respectively. This is
on the lower end of some model guidance and model trends, which
would bring triple digit heat into Cameron County and topple the
McAllen record as well.

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             83  65  88  67 /   0   0   0   0
HARLINGEN               89  62  91  65 /   0   0   0   0
MCALLEN                 95  64  95  68 /   0   0   0   0
RIO GRANDE CITY         97  59  95  64 /   0   0   0   0
SOUTH PADRE ISLAND      74  63  75  65 /   0   0   0   0
BAYVIEW/PORT ISABEL     83  63  84  65 /   0   0   0   0

&&

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

$$

SHORT TERM...60
LONG TERM....56
AVIATION...60-BE