Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 221204 AAA
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
704 AM CDT Sun Apr 22 2018

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

&&

.AVIATION...The conv along the southward moving cold front has
died off. So expect the main impact from the fropa for the RGV
airports will be the anticipated wind shift and the morning low
ceilings and vsbys. Patchy areas of dense fog have broken out
ahead of the cold front this morning. But these should be pretty
short lived as drier air will be filtering into the region from
the north improving the aviation conditions this morning. Expect
VFR conditions to return to the region later this morning as
northerly surface winds overspread the area. These VFR conditions
will persist into the afternoon and evening for all three RGV
airports.

&&

.PREV DISCUSSION... /issued 425 AM CDT Sun Apr 22 2018/

SHORT TERM (Now through Monday): The cold front associated with the
closed 500 mb low now centered over the OK/AR border region is
moving south and will enter through northern counties of Deep South
TX over the next hour. KBRO and KCRP radar imagery shows a narrow
line of showers firing up along this front. These showers may hold
together long enough to moving across mainly the eastern sections of
the RGV early this morning. The cold front will then move south of
the Rio Grande River later this morning allowing a little cooler and
drier air to filter into the region reducing the cld cover and any
lingering pops.

The northerly low level wind flow will be pretty short lived as the
surface ridging behind the cold front moves over the southeast
allowing for a pretty quick return of easterly low level winds on
Mon.

Since the CAA will be pretty minimal with this fropa expect enough
daytime heating to occur today and Mon to limit the overall cooldown
of the high temps. So will lean towards the warmer side of temp
guidance for maxes Sun/Mon. Enough drier air will move into the
region tonight to allow for slight cooler overnight lows. Will go
close to the short term model blend for mins tonight.

Some patchy morning fog will break out across the RGV ahead of the
cold front as the surface winds become light and variable. Some
localized areas of dense fog will be possible but will likely be
short lived. So do not expect any dense fog advisory this morning.

LONG TERM (Monday Night through Saturday): The latest GFS/ECMWF are
in fairly good agreement with a 500mb low/trough over the middle
Tennessee region Monday night. Dry west to northwest flow aloft and
surface high pressure across Texas will provide subsidence across
deep south Texas Monday night and Tuesday. The next 500mb shortwave
trough moves over the northern Plains Tuesday and moves into the
Middle Mississippi River valley Wednesday. There are some
differences between the GFS and ECMWF on timing of this mid level
feature. As a result, there are differences on the timing of the
passage of the weak cold front moving into the CWA Wednesday night
into Thursday. Moisture will increase and pool across the area
Wednesday night into Thursday with the approaching front. A slight
chance of showers and thunderstorms are forecast across deep south
Texas Wednesday night through Thursday night.

Models continue to diverge with the mid to upper level pattern and
with the amount of moisture across the region Friday and Saturday.
The latest ECMWF remains wetter than the GFS, as the ECMWF is
advertising another weak cold front moving into deep south Texas.
The ECMWF is also indicating some robust convection moving across
the area with the front on Friday, while the GFS shows limited rain
chances. Will continue to mention a slight chance of showers and
thunderstorms for Friday and lingering showers for Saturday.

MARINE (Now through Monday): The PGF in the wake of the cold front
moving across the lower TX marine areas will increase briefly.
However it will not be strong enough today to require any SCA`s at
this time. SCEC wording will likely cover any of the larger swells
or gustier winds that occur after the front. The PGF will then
weaken as the low level flow becomes more E-NE tonight and Mon. This
will maintain some decent swells. However the flow will be too weak
to generate SCA conditions into Mon.

Monday Night through Thursday Night: Surface high pressure will
prevail across the western Gulf of Mexico Monday night through
Wednesday. A weak cold front is expected to move into the lower
Texas coastal waters Wednesday night into Thursday with winds
shifting to the northeast. A weak pressure gradient will support
light winds and low seas through the period.

&&

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

$$

This product is also available on the web at:
HTTP://WEATHER.GOV/RGV

Short Term/Aviation...60
Long Term...63
Graphicast/Upper Air...56



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