975
FXUS64 KBRO 151128 AAA
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
628 AM CDT Wed May 15 2024

...New AVIATION...

.SHORT TERM...
(Today through Thursday)
Issued at 347 AM CDT Wed May 15 2024

This portion of the forecast may be more interesting than the official
forecast would indicate.

First, GFS model guidance suggests that a Mesoscale Convective
Complex (MCC) will develop over the State of Coahuila in neighboring
Mexico this evening due to a 500 mb shortwave. This MCC will then
track east over the southern portion of the CRP CWFA and the
northern half (Zapata, Jim Hogg, Brooks, and Kenedy counties) of the
BRO CWFA tonight. HRRR model guidance has a similar scenario, with
blobs of convection approaching the Rio Grande River around sunset
this evening. Additionally, the Storm Prediction Center places a
sliver of Zapata and Starr counties in a Marginal Risk of severe
weather, with the remainder of Deep South Texas and the Rio Grande
Valley in a general risk of thunderstorms. For now, the official
forecast has little to no convection, and good consistency, for the
CRP and BRO CWFAs tonight. However, given everything mentioned
above, successive shifts will need to be vigilant, and may need to
eventually add convection to the forecast should the GFS and/or
HRRR model scenarios come to fruition.

Finally, well above normal daytime high temperatures are expected on
Thursday. When combined with relative humidity percentages, heat
index values will near, or even briefly touch, established Heat
Advisory criteria for portions of Deep South Texas and the Rio
Grande Valley for a smidgen of the afternoon hours of Thursday. For
now, though, no Heat Advisory will appear in the official forecast
for Thursday, and a thorough comparison of forecast versus observed
daytime highs and dewpoint temperatures for today will need to be
done tonight to determine if model guidance is running too hot and
moist, too cool and dry, or just about right.

&&

.LONG TERM...
(Thursday night through Tuesday)
Issued at 347 AM CDT Wed May 15 2024

Hot conditions look to persist through the long-term period as a
strong 591-594 dam sub-tropical heat dome sits overhead. With this
feature in place, 850 mb temperatures are expected to range between
22-28C Friday through Wednesday. This will translate to high
temperatures at the surface in the upper 90s to mid/upper 100s each
day through the forecast period. Nights will be warm and humid with
lows bottoming out in the mid 70s to lower 80s. Dry conditions will
persist with the sub-tropical high in place over the region.

&&

.AVIATION...
(12Z TAFS)
Issued at 623 AM CDT Wed May 15 2024

LIFR is prevailing at HRL right now due to fog, while BRO and MFE
are experiencing MVFR/VFR. MVFR to VFR will prevail at the aerodromes
after sunrise, with moderate to breezy winds and mostly cloudy skies.

&&

.MARINE...
Issued at 347 AM CDT Wed May 15 2024

Today through Thursday: Buoy 42020 reported southeast winds
around 12 knots gusting to around 14 knots with seas slightly
under 3.5 feet with a period of 7 seconds at 250 CDT/750 UTC.
Generally light to moderate winds and low to moderate seas will
prevail along the Lower Texas Coast through the period with high
pressure in control. However, the strength of the wind on Thursday
may be just enough to require Small Craft Should Exercise
Caution, mainly for the Laguna Madre and maybe the Gulf of Mexico
waters from 0 to 20 nautical miles offshore.

Thursday night through Wednesday....Light to moderate winds will
result in low to moderate seas through the long-term period.

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             91  80  94  80 /   0   0   0   0
HARLINGEN               93  77  97  78 /   0   0   0  10
MCALLEN                 96  80 100  80 /   0   0   0  10
RIO GRANDE CITY         97  79 100  78 /   0  10   0  10
SOUTH PADRE ISLAND      84  80  85  81 /   0  10   0   0
BAYVIEW/PORT ISABEL     88  79  92  78 /   0  10   0   0

&&

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

&&

$$