Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 231144 AAA

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
644 AM CDT Sat Sep 23 2017

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


.AVIATION...IR Satl imagery early this morning shows only some sct
clds over the RGV with thicker cld cover evident to our west over
northeastern Mexico. KBRO radar indicates only some isold marine
conv firing to our east moving northwest. Daytime heating in
combination with the afternoon sea breeze may result in some more
sct conv along with lower ceilings. This may result in some MVFR
ceilings this afternoon and early this evening. However expect
overall VFR conditions to prevail for the RGV TAF sites.


.PREV DISCUSSION... /issued 417 AM CDT Sat Sep 23 2017/

SHORT TERM (Now through Sunday): The 500 mb ridging currently over
the central and northeastern U.S. will be eroded by a deep closed
moving in from the western states and a weaker closed low drifting
west over the southeastern states. AS the 500 mb ridging gradually
breaks over the time heating will help drive isold/sct
conv throughout the weekend. The 00z BRO sounding indicates that
overall moisture and instability is a little limited with an MUCAPE
of 1860 j/kg and a pwat of 1.94 inches. The GFS MOS pops are the
wettest versus the NAM/ECMWF numbers. Will lean towards the wetter
GFS pops as the RGV has seen pretty decent conv over the last couple
of days. The latest KBRO radar imagery also indicates some conv over
the Gulf waters trying to edge into the inland areas early this

Will go close to persistence for temps around the RGV as short term
guidance is in reasonable agreement for highs/lows.

LONG TERM (Sunday Night through Friday): Deep South Texas will
continue to be on the western side of a mid-level ridge over the
central Gulf and a mid-level trough over the western CONUS. Surface
high pressure across the southeast United States extending into the
northern Gulf of Mexico will prevail Sunday night and Monday. A cold
front is expected to move into northern Texas on Tuesday and
gradually move south through the week. Deep tropical moisture is
expected to pool ahead and along the frontal boundary. The latest
GFS/ECMWF suggests the cold front will move into deep south Texas by
late week. Precipitable water values near or above two inches will
support isolated to scattered showers and thunderstorms through most
of the period. Rain chances diminish by Friday night as drier air
filters into the region in the wake of the front. Temperatures will
to remain above normal through Thursday night due to abundant cloud
cover and high dewpoints. Near to slightly below normal temperatures
are expected Friday and Friday night in the wake of the front.

MARINE (Now through Sunday): Broad surface ridging sprawled over
the eastern states will maintain light to moderate winds and seas
across the lower TX coastline. Expect E-SE winds across the region
with Gulf seas ranging generally in the 2 to 3 foot range. A light
to moderate chop is expected on the Laguna Madre. No SCA conditions
expected through Sunday.

Sunday Night through Wednesday Night: Surface high pressure
across the northeast Gulf of Mexico will maintain light to
moderate southeast flow and low to moderate seas across the lower
Texas coastal waters through midweek. A cold front will approach
deep south Texas and the adjacent coastal waters by late in the
week which will result in higher winds and seas. Small craft
exercise cautions conditions likely in the wake of the front.
Isolated to scattered showers and thunderstorms will also be
possible at times through the period.




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