Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 271122 AAA

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
622 AM CDT Thu Jul 27 2017

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


.AVIATION...Daytime CU field will be limited today as drier air
begins to move into the region today. Shower activity will also
be minimized. Southeast winds will be modest at 10 to 15 knots.
Light winds and clear skies return after sunset.


.PREV DISCUSSION... /issued 402 AM CDT Thu Jul 27 2017/

SHORT TERM (Now through friday): Ample moisture remains in place
across Deep South Texas this morning, with GOES sounder noting PW
value around 2.1 inches still. Main difference between yesterday
and today will be the departure of the inverted trough as it
drifts west underneath the dominant US ridge. As the ridge builds
in, some drier air will return to the region between 5000 and
10000 feet. This will help cap off the atmosphere through most of
the day, keeping convection minimized. Highs will yet again reach
the upper 90s and low 100s for the region. Forecast PW values will
be down to near 1.5 inches by dawn Friday, continuing the dry and
hot forecast. Highs will tick upwards a few degrees Friday, with
100 degree temps reaching to the US77 corridor.

LONG TERM (Friday Night through Wednesday):Long term forecast
remains on track with models consensus in good agreement and
consistency. A very hot and dry weekend is in store then hopefully
a slight temperature reprieve as the chance of rain continues to
ramp up next week.

The mid-level 500mb ridge expands across the western states and
Texas while a strong mid level trough digs along the Eastern
Seaboard. A cold front, associated with the eastern trough, works
its way unusually far south moving into the Northern Gulf of
Mexico late Sunday/Monday with fair agreement among the GFS,
Canadian and ECMWF pushing the weakening front into our coastal
waters Tuesday. Moisture to begin to increase as early as Monday
but with higher moisture content in the vicinity of the frontal
boundary Tuesday looks like the best chance of rain for most
areas. With plenty of uncertainty on this front, since it is the
end of July and fronts are not very common this time of year, will
continue to broad brush pops at 20 percent Monday through
Wednesday. Temperatures peak this weekend with McAllen possibly
seeing one or two records being broken while Harlingen and
Brownsville look to be below record levels, but none the less the
heat will be on. As mentioned, some reprieve in the heat next
week as the chance of rain increases. Heat indices to remain just
below advisory levels (110+) this weekend with dewpoints lower
then usually with the building ridge and increased subsidence. As
surface moisture increases though next week and the isolated
nature of the rain chances could spell out higher HI numbers.

MARINE:(Now through friday): Winds have steadily decreased across
the Gulf waters overnight, allowing seas to begin to relax. Lighter
southeast flow today and tomorrow will remain near 10 knots, keeping
swells 3 feet or less through the period. Drier air return aloft
later today, ending any rainfall threat through the rest of the

Friday night through Monday...Weak surface ridge over the Gulf
waters to settle over the Western Gulf this weekend while a weak
cold front works its way into the Western Gulf next week keeping
the pressure gradient weak. Light to occasional moderate southeast
winds this weekend becoming east later Monday and Tuesday.
Relative rainfree conditions Saturday and Sunday with isolated
to scattered showers and thunderstorms next week are anticipated
with the approach of the front.




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