Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 092132

Area Forecast Discussion
National Weather Service Brownsville TX
332 PM CST Sat Dec 9 2017

.SHORT TERM (Tonight through Sunday Night): After several days well
below average and gloomy conditions, today was like a breath of
fresh air.  Mostly sunny skies and much warmer temperatures, not a
bad start to the weekend at all. Winds are a tad gusty, so there is
still some chill to the air. Tonight will be another cool night as
lows drop into the upper 30s and lower 40s across the region. Like
this morning, there may be some patchy frost here or there in the
cooler, more sheltered locations.

The overall upper level pattern doesn`t change through the short
term (thanks to the Rex block that develops across the western
U.S.).  This will continue to allow dry northwesterly flow to
prevail.  Dry northwesterly flow aloft as well as surface high
pressure settling into the area will keep skies clear/sunny and
temperatures around or slightly below average.

.LONG TERM (Monday through Saturday): The 500 mb Rex Block will
persist to the west of TX Mon and Tues with broad and deep 500 mb
troffing dominating the eastern states. A series of fast moving
short waves will dive out of western Canada Wed and Thurs which
will break down the Rex blocking pattern. These short waves will
push into the southwestern and south central Plains states Thurs
which will push a cold front through the RGV late in the day with
some mild CAA moving in behind the front. Meanwhile to our
southwest a closed 500 mb Baja low will form up which will
maintain some decent moisture advection over the area which could
interact areas of 500 mb vorticity advecting over the region to
generate some isold/sct conv late in the forecast period.

The GFs and ECMWF are in pretty good agreement on warming temps
and near zero pops up through Thurs with the ECMWF showing some
stronger CAA after the front on Fri and Sat versus the GFS. The
GFS is a bit wetter on pops for Fri and Sat also versus the ECMWF
which maintains only some slgt chc pops here. Will lean towards
the warmer side of guidance through Day 7 and will go close to a
model blend for pops mainly for Fri and Sat as the GFS is showing
some wilder run to run swings in the pops late in the period.
Prefer the better stability of the ECMWF pops.

Overall confidence in the longer range forecast wording is above
average through Thurs and then drops to about average for Fri and
Sat due to the wider model differences.


.MARINE (Now through Sunday night): Marine conditions have improved
this afternoon. Wave heights have fallen into the 4 or 5 ft range
and winds are around 15kts or so. With the improvement went ahead
and dropped SCAs for the coastal water beyond 20nm at noon. Although
seas and winds remain moderate, gradual improvement will continue as
high pressure begins to settle into the region on Sunday.

Monday through Thursday Night: The PGF will remain fairly weak
throughout the longer range period with only some weak wind shifts
from the north to northeast affecting the region throughout next
week. None of these wind shifts will result in significant
increases in both the winds and seas throughout the upcoming CWF
period. No SCA conditions expected through Thurs.


BAYVIEW/PORT ISABEL  43  66  45  70 /   0   0   0   0
BROWNSVILLE          43  69  45  71 /   0   0   0   0
HARLINGEN            40  69  42  72 /   0   0   0   0
MCALLEN              43  69  43  73 /   0   0   0   0
RIO GRANDE CITY      40  69  40  73 /   0   0   0   0
SOUTH PADRE ISLAND   51  65  52  68 /   0   0   0   0




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