900
FXUS64 KBRO 021959
AFDBRO

Area Forecast Discussion
National Weather Service Brownsville TX
259 PM CDT Thu May 2 2024

...New SHORT TERM, LONG TERM, MARINE...

.SHORT TERM...
(Tonight through Friday night)
Issued at 251 PM CDT Thu May 2 2024

Will key off the SPC Day 2 outlook to start, focusing on Friday
night to Saturday morning. SPC places the County Warning Area in a
general thunderstorm risk area, with the extreme Upper Valley in a
marginal tstorm risk. The depicted SPC local area is essentially
part of a southward extension of what is forecast to be more active
convection over the southern High Plains on Friday. The southern
extension of the Texas dryline will likely lie just to the west of
the CWA Friday, extending south into Mexico along the Sierra Madre
Oriental range. That appears to be where a tstorm threat will first
become evident Friday afternoon. Confidence is still on the low
side, 10 to 20%, and the window (timeframe) is limited.

Otherwise, there may be patchy, light fog here and there overnight,
mainly across the Northern Ranchlands and near/over marine areas.
Rip current risk will likely continue to be moderate. Additionally,
slightly above average (by a few degrees) temperatures will occur,
tempered by ample cloud cover. Southeast winds will remain moderate
to breezy.

&&

.LONG TERM...
(Saturday through next Thursday)
Issued at 251 PM CDT Thu May 2 2024

Key Messages:

* Temperatures off to the races as early-season heat expected to
  build into the area next week

* Widespread triple digit heating expected Tuesday through Thursday

* Heat indices are expected to range between 105F-115F degrees
  across all of Deep South Texas and the Rio Grande Valley Monday
  through Thursday

* Little to no relief at night with overnight lows in the upper
  70s to near 80F Monday night through Thursday night; elevated
  cooling degree days (CDDs)

* Heat Advisories possibly needed Wednesday and Thursday with heat
  indices ranging between 110F-115F

* HeatRisk scores range from Moderate to Extreme over the region
  Tuesday through Thursday of next week (heat will likely affect
  anyone without effective cooling and/or adequate hydration)

The main weather headline during the long-term forecast period will
be the HEAT. Global forecast models and ensembles (GEFS, CMC, ECE)
continue to advertise unseasonably warm to hot conditions developing
over Deep South Texas and the Rio Grande Valley next week. According
to recent model runs, a 591 dam sub-tropical heat dome centered over
central/southern Mexico is expected to strengthen and expand
northeastward into Deep South Texas/Rio Grande Valley and the
northern Gulf of Mexico next week. Current forecast indicates 500 mb
heights ranging between 588-591 dam. Monday and Tuesday, 850 mb
temperatures are expected to range between 22C-26C. By Wednesday and
Thursday (the hottest period of this stretch), 850 mb temperatures
are expected to range between 26C-30C. According to the NAEFS, these
temperatures are +2 to +3 STDEVs above normal.

This will translate to surface temperatures during the afternoon
hours ranging from the mid 90s to about 110F degrees Tuesday through
Thursday. When you factor in the elevated humidity levels (dewpoints
in the low to mid 70s), widespread 100+ degree heat indices are
expected. Monday and Tuesday, heat indices are expected to range
between 105F-110F degrees. Wednesday and Thursday, again the peak
of this early season heat episode, heat indices are expected to
range between 105F-115F degrees. Heat Advisories may be needed
Wednesday and Thursday. Our new HeatRisk Tool is scoring a
continuation of mainly moderate heat risk Saturday through Monday.
By Tuesday and Wednesday of next week, the HeatRisk increases to
anywhere from moderate to extreme. This would suggest the
likelihood of heat affecting anyone without effective cooling and
/or adequate hydration, and little to overnight relief.

People are urged to continue to monitor the latest forecast from the
National Weather Service in Brownsville/Rio Grande valley
(weather.gov/bro/). Leading up to this heat event, people should
take a proactive approach and heed the necessary precautions to
prepare for the heat. During the heat event next week, people
should follow all precaution and guidelines (i.e. hydrate at all
times, stay away from strenuous activities, wear light loose
fitting cloths, check on the pets and elderly and move them to air
conditioned facilities).

&&

.AVIATION...
(18Z TAFS)
Issued at 1227 PM CDT Thu May 2 2024

MVFR conditions prevail currently at the TAF sites due to lower
ceilings. Abundant low clouds are moving up from the southeast on
moderate winds. A few higher clouds may also be present based on
satellite imagery. In general, high pressure over the Gulf will
support a seasonal wind regime. Though there could be some
afternoon breaks here and there, guidance locks in MVFR ceilings
at the TAF sites from this evening through Friday morning.
Moderate to breezy southeast winds today will be just slightly
weaker on Friday.

&&

.MARINE...
Issued at 251 PM CDT Thu May 2 2024

Tonight through Friday night...Moderate to fresh southeast winds and
moderate to sometimes marginally high seas will prevail along the
lower Texas Coast through the short term. High pressure will be in
control over the Gulf, interacting with lower pressure deep inland
and upstream to provide a gradient conducive to persistent southeast
winds.

Saturday through Thursday....Moderate winds and seas are
expected to persist Saturday through Thursday. There could be times
of Small Craft Exercise Caution (SCEC) conditions taking place
through the long-term period.

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             78  90  76  89 /  10  10   0   0
HARLINGEN               75  92  74  91 /   0  10   0   0
MCALLEN                 78  94  77  93 /   0  20  10   0
RIO GRANDE CITY         76  94  75  94 /   0  20  10  10
SOUTH PADRE ISLAND      77  82  77  81 /  10  10   0   0
BAYVIEW/PORT ISABEL     76  87  75  87 /  10  10   0   0

&&

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

$$

SHORT TERM...54-BHM
LONG TERM....23-Evbuoma
AVIATION...54-BHM