Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 252344 AAA

Area Forecast Discussion...UPDATED
National Weather Service BROWNSVILLE TX
544 PM CST Fri Nov 25 2016

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

.AVIATION...Satellite images and surface observations indicated
mostly mid to high level clouds across portions of the CWA early
this evening. Ceilings were near 6000ft at KHBV to near 9000ft at
KPIL and KT65. Expect VFR conditions to prevail the rest of the
evening before low clouds/fog develop across the Rio Grande valley
and northern ranchlands late tonight into early Sat morning as a
weak cold front moves into the area and stalls. MVFR
ceilings/visibilities will develop after 09Z Sat as a result.

.PREV DISCUSSION... /issued 246 PM CST Fri Nov 25 2016/
SHORT TERM (Tonight through Saturday Night): Cold front is
crawling through the Hill Country a currently, and is going to
have a very tough time reaching this far south anymore. Morning
sounding showed a moist atmosphere up t about 8000 feet, with
bone-dry atmosphere above that. Even with this capping, some low-
topped showers are still forming up along a weak seabreeze
boundary moving inland, and along an outflow boundary just making
landfall at SPI. Will continue with slight chance showers for the
region through the rest of the afternoon, albeit very isolated in
nature, and not producing appreciable rainfall amounts.

For the remainder of the short term, zonal flow aloft will
continue to anchor dry air aloft, while onshore flow at the
surface continues to push moisture inland. This will continue a
very small chance for a shower or two, mainly during the daytime
hours once heating begins. Lower level moisture will contribute
to continued daytime CU field, which will keep daytime highs
tomorrow right around normal in the upper 70s.

LONG TERM (Sunday through Friday):
Gulf high pressure will combine with plains low pressure to set
up moderate to breezy southeast winds Sunday, with high
temperatures rebounding into the 80s. The trend will continue
through Monday as a cold front approaches from the north. Winds
will be breezy to windy from the south on Monday with high
temperatures in the mid to upper 80s, which will be well above
normal and may be close to records for this time of year. Winds
will back late in the day with the approach of an initial cold
front, with convective activity more likely north of the CWA. A
few showers will move through the CWA Monday night with the front,
but should be mainly offshore. Low temperatures will decrease into
the 50s and 60s while high temperatures on Tuesday will top out
near 80.

A follow-on short wave trough moving around the main low to the
north will swing toward deep South Texas Mon night and Tuesday with
stronger high pressure moving south over the Rockies. This will
bring reinforcing high pressure to the CWA Tue night with somewhat
of secondary and stronger front Wednesday am. Shower and isolated
thunder chances will be a little better with the Wednesday morning
boundary. Low temps Tuesday night will decrease a few more degrees,
into the lower 50s with some lower 60s, while Wednesday high temps
will be mainly in the 70s. Skies will clear Wednesday afternoon
with breezy north winds, and fair weather will take charge.

Low temperatures will dip into the 40s for the Ranchlands and Brush
Country Wednesday night under mostly clear skies, with lower 50s
near the coast. Thursday high temperatures will again be in the 70s
as high pressure spreads over the area and shifts east. Winds will
swing around to the southeast by Thursday, and return moisture will
pump back over the area on Friday, with the models indicating some
light shower possibility with the old front coming back this way.

The 12z GFS and 00z ECMWF are in better agreement today with the
dual front scenario and timing, though there is some temperature
spread, with the ECMWF going for slightly warmer day time temps.
Monday especially would be quite toasty with the ECMWF solution. A
blend was used for most elements at this point.

Now through Saturday night: High pressure to the northeast will
direct surface flow onshore during the next 36 hours, with winds
generally from the east at 10 to 15 knots. With a fairly long
fetch across the Gulf expected this weekend, seas will rise to 3
to 5 feet for the Gulf Waters, and bringing a moderate chop on the
Laguna Madre. Atmospheric moisture near the surface will tap into
surface instability tonight and tomorrow night to produce widely
scattered shower activity, with brief gusty winds and occasional
brief downpours.

Sunday through Wednesday: On Sunday southeast to south winds will
increase to strong through the day in response to pressure falls
associated with a plains storm system, and will likely reach small
craft advisory criteria by afternoon, staying strong through late
Monday before relaxing ahead of an approaching cold front. Winds
will shift to moderate northeast with the initial cold front early
Tuesday, but will become strong from the north early Wednesday as
reinforcing high pressure arrives in the area. Wave heights will
build to between 8 and 10 feet offshore late Sunday into Monday and
will have a chance to settle down Monday night and Tuesday before
building again Wednesday with reinforcing high pressure.



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