Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 251120 AAA

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
620 AM CDT Mon Sep 25 2017

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


.AVIATION...Brownsville radar indicates a few showers moving
northwest across the lower Texas coastal waters early this
morning. Otherwise, a few passing clouds and light southeast
winds prevail across the Rio Grande Valley this morning. Isolated
to scattered showers and thunderstorms are expected across deep
south Texas today. Southeast winds will become moderate later this
morning into the afternoon with some gusts approaching 20 knots.
Winds will diminish to around 10 knots or less by late this
evening. VFR conditions expected for the next 24 hours.


.PREV DISCUSSION... /issued 430 AM CDT Mon Sep 25 2017/

SHORT TERM (Now through Tuesday): Deep South Texas will remain
between a large scale mid/upper level trough over the western half
of the U.S. and a mid/upper level low over the northern Gulf of
Mexico with weak mid-level ridging overhead through the period.
Moist southeast flow in the low levels and southwest flow aloft will
allow deep tropical moisture to increase across the region through
the period. BRO sounding from Sunday evening showed a precipitable
water value of 1.73 inches which is close to the recent GOES-16
value of 1.80 inches. Brownsville radar currently shows a few
streamer showers moving northwest across the lower Texas coastal
waters this morning.

The western 500mb trough will build eastward today into Tuesday with
deep layer moisture increasing through the period. Isolated to
scattered showers and thunderstorms expected today into Tuesday. The
main issue in the short term will be the amount of cloud cover which
may impact rain chances and high temperatures for today and Tuesday.
The best rain chances will be across Zapata, Starr and Jim Hogg
counties due to higher QPF and the close proximity to the 500mb
trough. Made only minor adjustments to the inherited temperatures,
cloudiness and pops. Will lean towards of a blend of the
MET/MAV/ECMWF for pops.

LONG TERM (Tuesday Night through Sunday): Isolated to scattered
showers and thunderstorms will dominate through the entire long
term forecast period. The anticipated weather will be the result
of persistent 500 mb troughiness over the Desert Southwest,
precipitable water values generally between 2 and 2.25 inches
within Deep South Texas and the Rio Grande Valley, and a weak cold
front that will drop through most of the Lone Star State. With the
increased rain chances and expected significant cloud cover,
daytime high and overnight low temperatures will finally range at
near to slightly above normal levels.

MARINE (Now through Tuesday): Surface high pressure across the
southeastern United States will remain in control through the
period. Mariners can expected favorable marine conditions as light
to moderate southeast winds and low seas continue. Isolated to
scattered showers and thunderstorms will prevail through Tuesday.

Tuesday Night through Sunday: Generally moderate winds and seas
are expected along the Lower Texas Coast through the period with
surface high pressure in control. Small Craft Exercise Caution and
Small Craft Advisory are not anticipated to be needed.




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