FXUS64 KBRO 192341 AAA

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
641 PM CDT Mon Aug 19 2019

.DISCUSSION...Updated for latest aviation discussion below.


.AVIATION...VFR expected to predominate at the RGV terminals over
the next 24 hours. Can't rule out brief periods of higher MVFR
ceilings at any of the airports overnight, per obs from last night
and RAP/BUFKIT forecast soundings. Ceilings, if any, should be
very brief. Breezy SE winds will subside after sunset, with
somewhat lower daytime winds speeds expected on Tuesday vs. today.
A wind-shift to ESE with the sea-breeze boundary is expected mid-
afternoon. An isolated, brief streamer shower passing over BRO
early in the morning can't be ruled out, but should cause little-
to-no impact.


.PREV DISCUSSION... /issued 253 PM CDT Mon Aug 19 2019/

SHORT TERM (Now through Tuesday night): Heat index values are
currently near 115 degrees in Brownsville while heat index values
range from 105 to to 110 degrees across the eastern portions of the
CWA this afternoon. Will continue current heat advisory in effect as
temperatures will remain hot the rest of the afternoon into the
early evening and dewpoint temperatures remain in the lower to mid
70s across Cameron and Hidalgo counties. The only relief to the heat
today was the brief showers that developed along the seabreeze front
across the coastal counties. Unfortunately...Brownsville did not see
any relief to the heat as the record high temperature of 100 degrees
was tied today...previously set in 1915.

GOES-16 total precipitable water value satellite images are at least
encouraging as they indicate PW values near 2 inches across the
northwest Gulf of Mexico and the coastal sections of Texas this
afternoon. With the isolated showers that developed across the
coastal counties today...at least the potential exists for
additional seabreeze convection Tues afternoon. At the very
least...the increase in cloud cover Tuesday will provide some
respite to the heat but it will still remain hot. Currently not
expecting heat advisory conditions for tomorrow and record high
temperatures but it will still be hot as the 500mb subtropical ridge
across south-central United States continues to provide strong
subsidence across western portions of south Texas.

LONG TERM (Wednesday through Monday): An inverted trough will
approach deep South Texas while pushing the prevailing 500 mb ridge
further north into the Southern Plains and Four Corners region on
Wednesday. This mid level feature will allow deeper moisture to
increase across the region mid to late week. The best rain chances
are expected to remain across the eastern portions of the CWA and
over the Gulf waters Wednesday through Friday. The increase in cloud
cover and rain chances should keep high temperatures a bit lower
through mid to late week.

The rest of the forecast period is dependent on the development of a
closed 500mb low across the northwest Gulf of Mexico by late in the
week. The ECMWF continues to indicate that this feature will move
along the northwestern Gulf of Mexico on Friday with most of the
moisture remaining offshore with subsidence across the CWA. While,
the GFS shows a weaker and wetter system moving west across the
northwestern Gulf. No significant changes were made to the previous
pop and temperature grids. Will keep the mention of a slight chance
to chance of showers and thunderstorms across the CWA through the
weekend into early next week.

MARINE (Now through Tuesday night): Seas were near 4.3 feet with
south to southeast winds near 9.7 knots at buoy020 early this
afternoon. Light to moderate southeast winds winds will prevail
across the coastal waters tonight with weak surface high pressure
across the Gulf of Mexico. The pressure gradient will weaken across
the lower Texas coast Tuesday. Light southeast winds will prevail
across the western Gulf of Mexico Tuesday with slightly higher winds
across the Laguna Madre Tues afternoon. Winds will increase slightly
across the offshore waters Tues night as the winds decouple across
the bay waters.

Wednesday through Saturday...Light to moderate southeast winds
and low to moderate seas will prevail Wednesday through Friday
night. Showers and thunderstorms will be possible at times across
the coastal waters through the period.

FIRE WEATHER...Relative humidity values have fallen below 35
percent across the western portions of the CWA this afternoon as
winds have increased to 15 to 20 mph with gusts to 25 mph. With
critically dry fuels across most of deep south Texas...have issued a
fire danger statement for the CWA except across the coastal counties
for this afternoon. RH values are expected to be slightly lower
across the western portions of the CWA Tues afternoon and 20 foot
winds are expected to be similar to today so a fire danger statement
will likely be needed again tomorrow.




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