Area Forecast Discussion
Issued by NWS Brownsville, TX
FXUS64 KBRO 250040 AAA
Area Forecast Discussion...UPDATED
National Weather Service BROWNSVILLE TX
640 PM CST Tue Jan 24 2017
.DISCUSSION...Updated for latest aviation discussion below.
.AVIATION...Mostly VFR conditions will prevail this evening with
possible brief MVFR near BRO. Observations indicate some low level
cumulus clouds are moving northward as low level moisture
increases tonight ahead of a cold front, but widespread clouds are
not anticipated until after midnight. Wednesday morning,
increasing clouds are expected as moisture pools ahead of the cold
front. MVFR ceilings are more likely before the dry cold front
can scatter out the clouds. Winds will increase out of the north
mid-morning tomorrow after the front moves through the area,
leading to VFR conditions the rest of the day.
.PREV DISCUSSION... /issued 247 PM CST Tue Jan 24 2017/
SHORT TERM (Tonight through Wednesday Night): Winds continue to
reach wind advisory criteria across the coastal sections of the CWA
this afternoon. Will continue wind advisory for
Cameron...Willacy...Kenedy and Hidalgo counties through 5 pm. Winds
should diminish early this evening as the strong winds aloft
decouple from the surface with the loss of diurnal heating. The
pressure gradient will diminish across the lower Texas coast tonight
as a cold front moves across south central TX. Winds will continue
to diminish tonight into early Wednesday before the front moves
through the northern portions of the CWA Wed morning. Patchy fog
will develop late tonight into early Wed morning as clear skies and
relatively light winds allow fog to develop. Drier and slightly
cooler air will filter into deep south TX in the wake of the cold
front Wednesday. This will provide slightly cooler high temperatures
Wed afternoon and cooler low temperatures Wed night as a result.
LONG TERM (Thursday through Tuesday): The forecast period begins
with zonal flow aloft and surface high pressure across Texas.
This will result in near normal temperatures and dry conditions
across Deep South Texas and the Rio Grande Valley Thursday and
Friday. High temperatures Thursday and Friday will be generally in
the low 70s with low temperatures Thursday night mainly in the
upper 40s to lower 50s. The combination of a weak coastal trough,
an mid level short wave trough approaching from the west and
sufficient moisture in place, will support increasing rain
chances Friday night. The best rain chances appear to be on
Saturday as deeper moisture moves across the area. Rain chances
begin to diminish on Sunday as drier air filters into the region.
A closed low eventually dives down over Northwest Mexico and
tracks slowly east. However, the latest GFS/ECMWF differ on the
placement and the timing of this 500mb low. This approaching mid
level feature should trigger rain chances again Tuesday and
MARINE (Tonight through Wednesday night): Seas were near 6 feet
with south winds near 21 knots at buoy020 this afternoon. Moderate
to strong south winds will prevail across the coastal waters tonight
as the pressure gradient remains strong across the lower Texas
coast. Will extend SCA for the Laguna Madre and nearshore waters
through 6 pm and the far offshore waters through 9 pm. Winds will
gradually diminish offshore late tonight into early Wed morning as
the pressure gradient weakens ahead of a cold front moving through
the coastal waters Wed morning. Winds will shift to the north Wed
morning and increase Wed afternoon in the wake of the front.
Moderate to strong northeast winds will prevail across the western
Gulf of Mexico Wed night. Small craft advisories will likely be
needed for the offshore waters Wed afternoon through Wed night.
Thursday through Sunday...Marine conditions quickly improve on
Thursday as surface high pressure moves east weakening the pressure
gradient. Moderate northeast winds gradually shift to the east on
Friday with seas slowly subsiding. Another northeast to north
surge arrives Saturday with adverse marine conditions developing.
FIRE WEATHER (Tonight through Wednesday night): Borderline red flag
warning conditions have developed across the central portions of the
CWA with southerly winds 20 to 25 mph and relative humidity levels
near 35 percent. Winds will diminish and RH values will recover
tonight into early Wednesday as the pressure gradient weakens ahead
of a cold front moving through the northern ranchlands Wed morning
and moisture pools along and ahead of the front. Once the front
moves through the rest of the CWA Wed morning...winds will shift to
the north and increase while RH values crash...mainly across the
western and central portions of the CWA. Will go ahead and issue a
fire weather watch for Wed afternoon except across the coastal
TX...Fire Weather Watch Wednesday afternoon for TXZ248>250-252-253.
GM...Small Craft Advisory until midnight CST tonight for GMZ170-175.
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