Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 211758
AFDBRO

Area Forecast Discussion
National Weather Service Brownsville TX
1258 PM CDT Sat Apr 21 2018

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

&&

.AVIATION...Latest surface obs and local satellite data indicate
broken to overcast skies with MVFR to low end VFR ceilings. This
will continue through the afternoon with occasional nearby light
isolated shower activity. Winds will also trend breezy this
afternoon. Any showers will come to an end by this evening while
the breezy conditions decline into the night as a cold front
approaches the area from the north. Expect overcast conditions
through the night with IFR ceilings during the overnight. Winds
may become light enough ahead of the front for patchy fog as well.
The front is expected to move through around sunrise. Winds will
increase out of the north behind the front with gradually
improving ceilings.

&&

.PREV DISCUSSION... /issued 654 AM CDT Sat Apr 21 2018/

DISCUSSION...Updated for latest aviation discussion below.

AVIATION...KBRO and KCRP radar indicate a small area of conv
firing east of LRD and is moving east towards the Coastal Bend
region early this morning. So far none of this conv has been
attempting to expand southwards towards the RGV. So for now, Will
leave out any mention of conv in the current RGV TAF sets. IR
satl imagery shows some areas of ragged low level cld decks moving
from south to north across the RGV resulting in a mixture of
MVFR/VFR ceilings. Expect the low level cld decks over the RGV to
persist through the morning hours allowing the MVFR ceilings to
persist. The increasing diurnal heating in combination with the
strengthening SE low level flow will likely mix out some of the
lower ceilings that form up this morning. This will likely improve
the aviation conditions a bit later today allowing for VFR
conditions to prevail. Expect another round of MVFR ceilings later
tonight through Sun morning as the nocturnal ceilings reform.

PREV DISCUSSION... /issued 421 AM CDT Sat Apr 21 2018/

SHORT TERM (Now through Sunday): The 500 mb closed low over the
Desert SW will move steadily east today and Sun. As the closed low
approaches, an elongated lobe of deeper layer moisture will sweep
across central and southern TX today. Daytime heating in combination
with areas of vorticity rotating around the south side of the 500 mb
low could help fire off some isold conv later this afternoon.
However, the best of the overall moisture values will remain limited
to those locations mainly to the north of the RGV. So for now will
only mention some slgt chc pops for this afternoon.

The 500 mb closed low will continue moving eastwards on Sun which
will in turn bring a fairly mild cold front through the RGV Sun
morning. Deep layer moisture remains even lower on sun ahead of the
cold front passage. So will mention only silent 10 % pops for Sun.

Ahead of the frontal passage, the WAA will maintain high temps in
the 80s to lower 90s today. Despite the northerly low level winds on
Sun increasing the CAA, the atms will be pretty dry on Sun which
will allow the temps to moderate somewhat due to the daytime
heating. So expect no major differences in temps between Sat and
Sun.

LONG TERM (Sunday Night through Friday): A 500mb low/trough over
the ArkLaMiss area Sunday night will slowly move eastward over the
middle Tennessee region by Tuesday. Slightly cooler and drier air
will filter into the area on Sunday night as surface high pressure
builds across the region. Some moisture is expected to increase
across northeast Mexico Sunday night and Monday but convection
should remain well to the southwest of the area. Dry northwest flow
aloft and surface high pressure across Texas will provide subsidence
across the CWA Monday through Tuesday.

The next 500mb shortwave trough moves over the Northern Plains
Tuesday and into the Midwest Wednesday. The latest ECMWF and GFS
continue to differ on the placement and strengthen of this next
upper level system. This will push another weak cold front into
south Texas Wednesday afternoon. The front is expected to stall
across the region Wednesday night into Thursday. Moisture is
forecast to gradually increase across deep south Texas Wednesday
night into Thursday. The ECWMF remains more robust with pops than
the GFS, especially for Wednesday. However, due to limited moisture
above 850mb and differences in the models, will maintain a dry
forecast through Thursday for now. A stronger 500mb shortwave trough
is expected to develop and move over the central U.S. by late week.
This through should push another cold front into the CWA on Friday
providing a slight chance of showers and thunderstorms across the
area Thursday night into Friday.

MARINE (Now through Sunday): Surface obs and Buoy data from along
the lower TX coastline shows SCEC conditions in place early this
morning with several ob sites reporting gusts of around 20 kts.
These moderate SE winds will persist throughout today as the decent
PGF continues ahead of the surface low developing over the TX/OK
Panhandle region. The PGF will then weaken somewhat as the cold
front approaches the region from the north. After the fropa tomorrow
morning fairly strong N-NE low level winds will spread across the
region. However, the post frontal low level flow does not appear
strong enough on Sun to require an SCA at this time.

Sunday Night through Wednesday Night: Light to moderate northeast
winds and low to moderate seas are expected Sunday night and Monday
as high pressure builds into the region. Surface high pressure will
settle across the western Gulf through Midweek. Light winds and low
seas will prevail Monday night through Wednesday night as the weak
pressure gradient remains weak along the lower Texas coast.

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...None.
&&

$$

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HTTP://WEATHER.GOV/RGV

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