395
FXUS64 KBRO 160213 AAB
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
913 PM CDT Wed May 15 2024

...New UPDATE...

.UPDATE...
Issued at 908 PM CDT Wed May 15 2024

POPs were lowered this evening due to inactivity over the Sierra
Madre. Brownsville OOZ sounding indicated a large cap over the
region and with no significant disturbance within the southwest
flow aloft, deep convection is not anticipated to develop tonight.
Isolated streamer showers are possible after midnight over the
Gulf of Mexico with a few possibly nearing the lower and middle
RGV.

&&

.SHORT TERM...
(Tonight through Thursday night)
Issued at 254 PM CDT Wed May 15 2024

Key Messages:

- There is a low chance (20-30%) of showers and thunderstorms late
  this evening across the Northern Ranchlands.

- The combination of above normal temperatures and humidity will
  result in triple-digit heat index values across Deep South
  Texas.

- A Heat Advisory may be needed for portions of the region
  Thursday afternoon.

Radar and satellite imagery depict rain-free conditions and partly
cloudy skies across Deep South Texas. Low level southerly to
southeasterly flow will increase in speed in response to an
approaching upper level trough from the Desert Southwest. This
will result in stratus clouds spreading across the region by this
evening, in addition to increasing precipitable water values.
Isolated to scattered strong to severe thunderstorms are expected
to develop along a dryline across the Texas Hill Country late this
afternoon, and as far south as Mexico along the Sierra Madre
mountains. Despite the presence of steep lapse rates, modest
instability, high moisture content, and high shear values, weak
forcing will limit the eastward extent of any strong to severe
thunderstorms across the region late this evening and tonight.
However, there has been run-to-run consistency that an isolated
strong to severe thunderstorm or two will make it toward the
Northern Ranchlands and Upper RGV after 9-10PM this evening. Any
activity should be on a downward trend as it tracks east as
instability wanes overnight. Otherwise, warm air advection showers
may develop along the I-69 corridor tonight. The combination of
increasing low level southerly flow and overcast skies will keep
temperature in the 70s and low 80s tonight.

Thursday will be another very warm day, with temperatures around
5-8 degrees above normal for mid May. In combination with the
return of higher humidity, heat index values will approach the
triple digits region wide. The exception will be along the Lower
Texas beaches, where heat index values will remain in the 90s.
Portions of Deep South Texas, mainly areas along/east of US-281,
will likely realize "feels like" temperatures in the 111-115
range tomorrow afternoon. A Heat Advisory will likely be needed
for Cameron, Willacy, Hidalgo, and Kenedy counties, but look
marginal for Brooks County. Will hold off on issuing any heat
headlines at this time, but an advisory may be needed for the
eastern half of the CWA. Regardless of any heat headlines, the NWS
HeatRisk tool highlights a major risk of heat-related impacts for
those that are not properly hydrated or do not have effective
cooling in place. Isolated showers may develop Thursday
afternoon, mainly over the far northeastern zones, and increased
cloud cover may temper the heat by a degree or two. Otherwise,
another mild, humid, and cloudy night is expected Thursday night
with lows in the upper 70s and low 80s.

&&

.LONG TERM...
(Friday through next Wednesday)
Issued at 254 PM CDT Wed May 15 2024

Key Messages:

- There is a low chance (20-30%) of showers and thunderstorms on
  Friday across Deep South Texas.

- The combination of above normal temperatures and humidity will
  result in triple-digit heat index values across the region
  through next week.

Overall, the long term forecast remains on track with mostly
rain-free conditions expected through next week across Deep South
Texas. The exception will be on Friday as a mid/upper level trough
approaches the Texas Hill Country/South Texas on Friday. Ahead of
this system, precipitable water values are forecast to be around
2-2.1 inches, well above the 90th percentile of 1.82 inches.
Although the better forcing for ascent will be just north of the
region, widely scattered showers and thunderstorms cannot be
ruled out as instability increases through the day.

Heading into the weekend and early next week, mid and upper level
ridging will build in from the west/southwest. This will allow for
a continued steady warming trend across Deep South Texas, with
high temperatures warming into the upper 90s along the immediate
coast to around 105-106 degrees across the Rio Grande Plains.
Triple digit heat indices are expected each afternoon in
combination with the humidity. Additional heat headlines may be
needed by mid week next week. Despite any formal headlines, the
NWS HeatRisk tool highlights a major risk of heat-related impacts
for those that are not properly hydrated or do not have effective
cooling in place.

&&

.AVIATION...
(00Z TAFS)
Issued at 609 PM CDT Wed May 15 2024

Currently, MVFR ceilings are beginning to work inland and are
expected to have spread across all TAF sites within a few hours
following sunset and persist through tonight. Winds will
gradually veer to more southeast in the early morning hours
Thursday and continue as ceilings gradually lift to VFR by
Thursday afternoon.

&&

.MARINE...
Issued at 254 PM CDT Wed May 15 2024

Tonight through Thursday night...Light to moderate winds and
low to moderate seas will prevail through the period. A tightening
pressure gradient will result in Small Craft Should Exercise
Caution conditions along the Laguna Madre and nearshore Gulf
waters Thursday afternoon.

Friday through Wednesday...Light to moderate winds and low to
moderate seas will prevail through next week.

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             80  94  80  95 /  20  10   0  20
HARLINGEN               78  97  77  97 /  10  10  10  20
MCALLEN                 80 100  80  99 /  10   0  10  20
RIO GRANDE CITY         78 100  78  98 /  10   0  10  20
SOUTH PADRE ISLAND      80  86  81  86 /  20   0   0  10
BAYVIEW/PORT ISABEL     80  92  78  93 /  10  10   0  20

&&

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

$$

UPDATE...65-Irish/59-Bogorad
SHORT TERM...22-Garcia
LONG TERM....22-Garcia
AVIATION...65-Irish