838
FXUS64 KBRO 212335 AAA
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
635 PM CDT Tue May 21 2024

...New AVIATION...

.SHORT TERM...
(Tonight through Wednesday night)
Issued at 243 PM CDT Tue May 21 2024

The main trend of the short term forecast period will be hot and
hot. A Heat Advisory is already in effect for Deep South Texas and
the Rio Grande Valley except along the coast and on the barrier
island. As the mid-level ridge continues to dominate the weather for
the region the temperatures are going to continue to be hot. The
expected high temperatures are in the range of upper 90s along the
coast, the island, and the Lower Rio Grande Valley, while the rest
of the region is in the triple digits. To add on to that, the
southeasterly winds will continue to bring in low-level moisture
that will keep the air humid. This will result in elevated heat
indices of around 111 to 113 for most of the area. A Heat Advisory
is likely to be issued for tomorrow as the heat indices are in the
range of 111 to 113.

While the previously mentioned low-level moisture will help develop
some low-level clouds, the chances of rain are very low. Due to the
mid-level ridge in place, the middle and upper levels of the
atmosphere are very stable and there is also plenty of dry air as
well. This will keep any showers and thunderstorms away from the
region.

As for the night time temperatures, do not expect too much relief
there as the sensible low temperatures will be in the upper 70s to
low 80s, but it will feel like being the in the low to mid 80s for
both nights.

The haze is expected to continue to persist with the ongoing
agricultural fires in southeast Mexico and the southeasterly flow
allowing to spread over the region. If you happen to be going to the
beach, there is a moderate risk of Rip Currents through tomorrow.

&&

.LONG TERM...
(Thursday through next Tuesday)
Issued at 243 PM CDT Tue May 21 2024

As it was with the short term forecast period, the long term
forecast period can be mostly summarized as being hot and hot. High
temperatures are expected to mostly in the in the triple digits with
a few areas along the coast, the barrier island, and Lower Rio
Grande Valley in the upper 90s.  However the heat indices are
expected to climb even further around Friday and through the early
work week to be in the range of 117 to 120. This will mean that
Excessive Heat Warnings and Watches will need to be issued by later
shifts. Night time low temperatures are expected to be in the range
of upper 70s to low 80s for each night.

With the mid-level ridge still very much in place for the duration
of the long term forecast period, rain chances remain very low.
While the southeasterly flow will allow for moisture to move into
Deep South Texas and the Rio Grande Valley, the dry and stable
middle and upper levels of the atmosphere will work to prevent the
development of showers and thunderstorms. There is perhaps an
opportunity for showers and thunderstorms to develop towards the
end of the long term forecast period with the passage of a mid-level
shortwave trough. However, that is a long time out and the forecast
models may change their tune on this mid-level shortwave trough.

&&

.AVIATION...
(00Z TAFS)
Issued at 617 PM CDT Tue May 21 2024

MVFR at KBRO due to the ceiling, with VFR in low clouds at KHRL
and KMFE. Low clouds will thicken late this evening and overnight
across the Lower RGV, resulting in MVFR conditions for all three
TAF sites. Light, patchy fog will also be possible, but southeast
winds will generally remain moderate, precluding significant
visibility impact. Southeast winds will strengthen to breezy by
mid-Wednesday morning, and ceilings will scatter out to VFR
conditions for the remainder of the day.

&&

.MARINE...
Issued at 243 PM CDT Tue May 21 2024

Tonight through Wednesday Night...A locally enhanced pressure
gradient due to a thermal low over Mexico and high pressure over the
Gulf, is expected to persist through Wednesday night that will
result in moderate to fresh southeasterly winds with slight to
moderate seas. Small Craft Exercise Caution is possible during the
afternoon.

Thursday through Next Tuesday...The interaction between a thermal
low over Mexico and high pressure over the Gulf of Mexico will
generate a locally enhanced pressure gradient that will produce
moderate to fresh southeasterly winds with slight to moderate seas.
Small Craft Exercise Caution is likely to be needed each day during
the afternoons, but a Small Craft Advisory can not be ruled out
either for those days as well.

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             98  81  96  81 /   0   0   0   0
HARLINGEN               99  77  99  78 /   0   0   0   0
MCALLEN                101  80 100  80 /   0   0   0   0
RIO GRANDE CITY        103  79 103  78 /   0   0   0   0
SOUTH PADRE ISLAND      87  81  87  82 /   0   0   0   0
BAYVIEW/PORT ISABEL     95  79  95  80 /   0   0   0   0

&&

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

$$

SHORT TERM...54-BHM
LONG TERM....60-BE
AVIATION...54-BHM