Area Forecast Discussion
Issued by NWS Brownsville, TX

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889
FXUS64 KBRO 220845
AFDBRO

Area Forecast Discussion
National Weather Service BROWNSVILLE TX
345 AM CDT THU SEP 22 2016

.SHORT TERM (Today through Friday): Another long, hot, mainly dry
summer comes to a close for Deep South Texas and the Rio Grande
Valley today, as the autumnal (fall) equinox begins officially at
921 AM CDT/1421 UTC this morning. Unfortunately, the ongoing spate
of days and nights with well above normal temperatures will persist
through the short term period of the forecast with no significant
weather systems poised to break the trend. Meanwhile, the most
recent KBRO upper air sounding from Wednesday evening showed a
much more moist atmosphere with nearly 2 inches of precipitable
water in the atmospheric column. This moisture, daytime heating,
and the transition of a weak surface area of low pressure from the
western Gulf of Mexico to the Middle Texas Coast will generate
isolated showers for the BRO CWFA today, with continued isolated
shower activity for the Lower Texas coastal waters tonight.
Remaining deep tropical moisture and an onshore flow will allow
the isolated convection to persist on Friday.

.LONG TERM (Friday Night through Wednesday): 500mb trough across
the western United States Friday will move eastward Saturday.
Surface low pressure will develop on the lee side of the Rockies
Saturday and moisture will pool along and ahead of a weak cold
front draped across the central United States. Showers and
thunderstorms will increase in coverage to the north and west of
the CWA Sunday and move into deep south TX Sun night as the front
moves through central TX into south TX. Will increase rain
chances for the Rio Grande valley and the northern ranchlands Sun
night into Monday as the frontal boundary moves across the lower
TX coast Monday. The rest of the forecast period appears to
provide at least a slight chance of rain even though the GFS and
the ECMWF have introduced different model solutions for Tuesday
and Wednesday compared to yesterday. The GFS progs drier air
filtering into the western portions of the CWA while a weak area
of low pressure develops across the western Gulf of Mexico and
moves towards the lower TX coast Wednesday. The ECMWF is now
advertising elevated convection across portions of southwest TX
with an upper level low developing across northern Mexico/west TX
Monday and meandering across the southwest U.S. through the rest
of the forecast period. Will mention a slight chance to chance of
showers and isolated thunderstorms through the middle of next week
hoping that the global models have a better handle of the synoptic
pattern.
&&

.MARINE:
Now through Friday...Buoy 42020 reported East winds around 6
knots gusting to around 10 knots with seas slightly under 2.5 feet
with a period of 5 seconds at 03 CDT/08 UTC. Weak surface low
pressure will transition from the western Gulf of Mexico today,
with surface high pressure resuming control of the weather pattern
tonight through Friday. Overall, light to moderate winds and low
to moderate seas will prevail for the Lower Texas coastal waters
during the entire forecast period with Small Craft Exercise
Caution and Small Craft Advisory still not anticipated to be
needed.

Friday night through Monday...Moderate southeast winds will
prevail across the coastal waters Fri night and Saturday with low
pressure across the Texas panhandle and high pressure across the
northeast Gulf of Mexico. The pressure gradient will increase
slightly Sat night and moderate to strong southeast winds will
develop Sat night and continue into Sunday. A weak cold front is
expected to move through the lower TX coast Monday. Small craft
advisories may be needed for the offshore waters Sun night and
portions of the coastal waters Monday as the front moves offshore.
&&

.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL  95  79  93  79 /  20   0  20  10
BROWNSVILLE          96  77  96  78 /  20   0  20  10
HARLINGEN            98  76  96  77 /  20   0  20  10
MCALLEN             100  78 100  77 /  20   0  20  10
RIO GRANDE CITY     101  77 101  77 /  20   0  20  10
SOUTH PADRE ISLAND   90  81  89  81 /  20  20  20  10
&&

.BRO Watches/Warnings/Advisories...
TX...None.
GM...None.
&&

$$

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