Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 022137

Area Forecast Discussion
National Weather Service BROWNSVILLE TX
337 PM CST Fri Dec 2 2016

.SHORT TERM (Tonight through Saturday Night): High dew point, mild
low level air will continue to pump north across the CWA tonight.
Rain chances will be on the increase, and ripples in the
overrunning southwest flow aloft, along with cooler temps aloft,
may be enough to help trigger some stronger isolated thunderstorms
across the Ranchlands and Brush Country. Higher rain chances will
remain focused primarily across the northern counties Saturday
and Saturday night as well, with somewhat better mid level forcing
developing as a cut off low sinks south into Northwest Mexico and
then moves east toward the CWA. Divergence ahead of the low will
fan out over Central Texas and South Texas, keeping rain chances
elevated during the short term, and a marginal risk of severe
weather has been posted by SPC for the entire CWA on Saturday.
Though forecast QPF amounts across the area are modest, in the
hundredths or tenths of an inch, locally heavy downpours, again
only if stronger storms develop, will be possible. Winds will
remain light to mdt out of the southeast, becoming breezy near the
coast Saturday afternoon. Temps will be well above normal, in the
60s and 70s, with low 80s across the area on Saturday. A cold
front is due on Sunday, during the first period of the long term.

.LONG TERM (Sunday through Friday): A strong 500 mb closed low
will swing across northern Mexico and southern Texas Sunday and
Monday providing good divergence aloft and uvv. Good deep layer
moisture will also pool ahead of this closed low which will
interact with the good dynamics provided by the closed low to
boost up the pcpn chcs early in the longer range period. There are
some concerns that the atms could destabilize enough ahead of the
closed low to help fire off some isold stg/marginally svr t-storms
on Sunday. However will not mention them in the ongoing forecast
due to uncertainties as to when and where any stg/svr development
could occur Sun into Sun night. As the 500 mb closed low exits
the region Mon and Mon Night a little cooler airmass will build
into the region lowering temps down close to climo for the area.
The RGV will then come under the influence of a more zonal 500 mb
pattern through Tues and Wed which will allow the temps to warm
somewhat as a southeast low level flow returns. Then another large
and broad 500 mb trough axis digging across the central portion
of the country will drive a strong cold front into the South
Central Plains states on Wed and Thurs setting the stage for a
more significant cool down towards the end of next week.

The ECMWF and GFS models are in a little better agreement today
versus yesterday but fairly large differences still persist mainly
for temps on Sunday and for the timing of the strong fropa later
next week. The ECMWF shows a much cooler solution for the high
temps on Sunday with this model favoring a quicker exit of the 500
mb low and faster CAA building in over the region. Meanwhile the
GFS lifts out the closed low more slowly which holds off the CAA
until much later in the day. The longer range models then show
better agreement for the middle portion of next week for both
temps and pops with the ECMWF showing a stronger fropa and
accordingly a stronger Canadian airmass towards the end of next.

So will opt for a general blend of the two longer range model sets
through day 7. Overall confidence is pretty decent for pops
especially for the weekend. However confidence is much lower for
high temps on Sun and for the post frontal passage temps later
next week.


.MARINE: (Now through Saturday night): Although local winds may veer
away from east during the short term, moderate or better east winds
will still persist over much of the Northeast Gulf basin, driving an
east swell toward the Lower Texas Coast. As a result, SCEC to low
end SCA conditions will be possible for the entire short term

Sunday through Wednesday...The PGF will be strong enough from
Sunday through Monday which will maintain SCA conditions mainly
for the offshore waters. The PGF will then weaken on Tuesday and
Wednesday as the 500 mb closed low and associated coastal surface
troffing start to move away from the region. So expect calmer
marine conditions to prevail then. However the next strong cold
front which will move through the area later next week will likely
set the stage for another round of strong SCA conditions starting
Wed night and continuing into Friday.


BAYVIEW/PORT ISABEL  74  82  71  78 /  30  20  40  50
BROWNSVILLE          73  83  71  80 /  20  20  40  50
HARLINGEN            73  84  69  79 /  30  20  40  60
MCALLEN              72  85  67  80 /  30  10  40  50
RIO GRANDE CITY      71  86  64  76 /  40  10  60  50
SOUTH PADRE ISLAND   75  80  72  77 /  20  20  40  50


GM...Small Craft Advisory until midnight CST tonight for GMZ170-175.



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