-- Discussion containing changed information from previous version are highlighted. --
312
FXUS64 KBRO 071720 AAB
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
1220 PM CDT Tue May 7 2024

...New AVIATION...

.SHORT TERM...
(Today through Wednesday)
Issued at 308 AM CDT Tue May 7 2024

Key Messages:

- Unseasonable heat is expected during the short term period across
Deep South Texas.

- Those spending a prolonged period outside will need to take
necessary heat precautions to avoid heat-related illnesses.

- Moderate risk of rip currents through Wednesday.

The overall weather pattern will promote above normal temperatures,
triple-digit heat indices, and rain-free conditions through the
short term period across Deep South Texas. At the surface, high
pressure centered over the eastern Gulf of Mexico will maintain well
established low-level southerly to southeasterly flow and allow for
high dew points to remain in place. Quasi-zonal flow aloft may allow
for a few embedded impulses to pass overhead, but drier air in the
mid levels and a cap in place will preclude any precipitation
chances.

Widespread low clouds will be slow to lift/scatter this morning, but
should begin to clear out from west to east by late this morning or
early afternoon. The latest suite of high res guidance does maintain
partial cloud cover across most of the region, with low clouds
likely remaining along the immediate coast and some high clouds
filtering in from the west/southwest. This may help with the
unseasonable heat this afternoon as high temperatures warm into the
mid 90s along/east of US-281 and upper 90s to around 101 degrees
west of US-281. In combination with the humidity, heat index values
will approach the triple-digits across most of Deep South Texas,
ranging from 101-113 degrees.

A caveat to the temperature forecast is the amount of cloud cover we
actually see this afternoon. GOES-16 Upper-Level Water Vapor IR
satellite imagery reveals the high clouds currently reside across
Mexico, but are gradually moving toward Deep South Texas. Higher
cloud cover than currently forecast may help temper the heat this
afternoon, which could result in a high temperature 1-3 degrees
cooler than currently forecast... and lower heat index values. Due
to this uncertainty, I have opted to hold off on the issuance of a
Heat Advisory for this afternoon. Otherwise, another mild and cloudy
night is expected tonight as widespread low clouds develop once
again. Low temperatures will fall into the 70s region wide.

Wednesday will be around 2-6 degrees warmer than Tuesday, with high
temperatures ranging from the mid 80s along the Lower Texas beaches
to around 101-106 degrees across the Upper RGV and Brush Country.
The main reason for this noticeable increase in temperatures is the
increase of 850mb temperatures due to warm air advection. Now, while
the air temperature will be highest across the western half of the
region, lower dew points will be in place due to the presence of a
dryline. This will result in heat index values measuring near or 1-3
degrees above the air temperature. Conversely, the presence of
higher dew points east of the dryline will result in heat index
values around 10-12 degrees above the air temperature. For areas
east of the dryline, heat index values will range from 109-113
degrees during the afternoon hours. A Heat Advisory will likely be
needed for portions of the region Wednesday afternoon.

&&

.LONG TERM...
(Wednesday Night through Monday)
Issued at 308 AM CDT Tue May 7 2024

The aforementioned dryline will move farthest to the east within
the BRO CWFA on Thursday, producing a ridiculous burst of daytime
heat. Well above normal high temperatures will occur, and a HEAT
ADVISORY is likely to be needed for the five easternmost counties
(Hidalgo, Brooks, Cameron, Willacy, and Kenedy).

Fortunately, the unseasonably warm temperatures experienced in the
Short Term and a fraction of the Long Term will come to end on
Friday, and persist through the remainder of the forecast period,
due to the Friday passage of a cold front. More seasonal daytime
highs and overnight lows are anticipated courtesy of the frontal
passage. An added bonus will be the possibility of isolated to
scattered showers and thunderstorms Friday through Monday,
produced initially by the cold front, but then subsequently by the
passage of a series of 500 mb disturbances. The most recent U.S.
Drought Monitor map of Texas places Abnormally Dry conditions
within Cameron, Hidalgo, and Starr counties, so the convection may
help to ease this condition ever so slightly where it occurs.

&&

.AVIATION...
-- Changed Discussion --
(18Z TAFS)
Issued at 1215 PM CDT Tue May 7 2024

MVFR ceilings should lift to VFR this afternoon across all
aerodromes. This evening, however, ceilings will lower again
thanks to the abundant moisture in the low levels of the
atmosphere and MVFR ceilings are expected. As we head into late
tonight/early Wednesday morning, hazy conditions may develop along
with IFR conditions.
-- End Changed Discussion --

&&

.MARINE...
(Today through Wednesday)
Issued at 308 AM CDT Tue May 7 2024

Light to moderate southeast winds and moderate seas will prevail
through the forecast period. Brief periods of Small Craft Exercise
Caution conditions will be possible each afternoon, especially
across the Laguna Madre and northern Gulf waters as wind speeds
increase.

(Wednesday Night through Monday)
Small Craft Exercise Caution and brief possible Small Craft
Advisory conditions will exist along the Lower Texas Coast
Wednesday night through Friday due to an enhanced pressure
gradient and the subsequent Friday passage of a cold front.
Outside of this time period, generally moderate winds and seas
are forecast.

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             92  77  94  78 /   0   0   0   0
HARLINGEN               96  76  98  76 /   0   0   0   0
MCALLEN                 98  77 101  78 /   0   0   0   0
RIO GRANDE CITY        100  76 105  76 /   0   0   0   0
SOUTH PADRE ISLAND      83  77  85  78 /   0   0   0   0
BAYVIEW/PORT ISABEL     89  76  93  76 /   0   0   0   0

&&

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

$$

SHORT TERM...22
LONG TERM....66
AVIATION...68-McGinnis