Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 311132 AAA

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
632 AM CDT Tue Mar 31 2020

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

.AVIATION...Satellite images and surface observations indicate a
mix of low to high level clouds across the CWA early this morning.
Ceilings were near 1100ft at KBRO to near 8000ft at KTXW.
Visibilities were near 5SM with fog at KHBV. Expect VFR to MVFR
conditions across the Rio Grande Valley this morning before a weak
cold front moves through the area later this morning. Expect VFR
conditions to prevail across the RGV this afternoon into this
evening as surface high pressure builds into deep south Texas in
the wake of the front.

.PREV DISCUSSION... /issued 312 AM CDT Tue Mar 31 2020/
SHORT TERM (Today through Wednesday): A weak cold front will move
through the Rio Grande Valley later this morning. May see some
patchy fog develop across the southern and eastern portions of the
CWA early this morning before the front pushes through the area.
The main impact from the front will be drier air moving into deep
south Texas today and with clearing skies and low relative
humidity this afternoon...temperatures will reach the lower to mid
90s across most of the CWA as a result. Temperatures will be
slightly cooler tonight with the drier air across the region.
Highs Wednesday will actually be cooler than today as an onshore
flow returns Wed morning and low to mid level moisture begins to
increase across northeast Mexico and deep south Texas Wednesday.

LONG TERM (Wednesday Night through Monday): A warm and more humid
night will be expected Wednesday night as dew points will be on the
rise with persistent southeasterly winds as surface high pressure
slides to the east. Afternoon high temperatures in the 90s will
return across the western half of the CWA on Thursday as moderate
southeasterly winds prevail. A couple of isolated rain showers,
primarily near the coast, couldn`t be ruled out on Thursday with
the low-level moisture return. Thursday night into Friday morning
will trend very humid and warm with overnight lows in the low to
mid 70s.

Rain chances will increase through the latter half of the day on
Friday into Saturday as a cold front approaches from the north,
which interacts with the pooling moisture across the region. The
best rain chances will occur from Friday night through Saturday
with the arrival of the front across Deep South Texas. With a
primarily zonal flow aloft with the parent shortwave energy
pulling northward, the front will likely stall across or just
south of the Rio Grande Valley. In addition to showers, enough
sufficient instability is in place for at least a slight chance
for thunderstorms. A strengthening mid-level ridge across the
western Gulf of Mexico on Sunday does lead to a bit of some
drier aloft but the frontal boundary remains close enough for
lingering chances for showers, perhaps a thunderstorm. The mid-
level ridge slides slightly to the east from Sunday night into
Monday, which allows for a more southwesterly flow to establish
aloft. This could promote the approach of possible convection
coming off the higher terrain in Mexico from Sunday night into
Monday, with the best rain chances focusing to the west.

Overall, mid-range models are in decent agreement through the
long term forecast period. Similar to the previous forecast
package, the 7-Day QPF values look to generally range between
0.25 and 0.75 inches, with the highest amounts favoring over
the western and northern portions of the CWA.

MARINE (Today through Wednesday): Seas were near 3 feet with
south winds near 8 knots at buoy020 early this morning. Light
south winds will shift to the northwest and increase later this
morning as a weak cold front moves through the coastal waters.
Moderate northwest will shift to the north this afternoon with
moderate to strong north winds developing across the far offshore
waters. Will word SCEC for the far offshore waters as a result.
Surface high pressure will build into the northwest Gulf of Mexico
in the wake of the front today into tonight. Light to moderate
northeast winds will prevail across the lower Texas coast tonight.
Winds will diminish and veer to the east Wednesday as the surface
ridge across east Texas moves eastward Wed afternoon.:

Wednesday through Saturday Night: Surface high pressure over the
Gulf of Mexico and the northern Gulf coast will lead to persistent
moderate east to southeasterly winds and mainly moderate seas
through early Saturday. A weak front allows winds to turn out of
the east-northeast from Saturday into Saturday night.
Occasionally, mariners may need to exercise caution, otherwise no
strong indications of sustained SCA conditions are noted. Showers
and thunderstorm chances will increase from Friday into Saturday
with the approach/arrival of the weak cold front.

FIRE WEATHER (Today): A weak cold front will move through the
Rio Grande Valley this morning and drier air will filter into deep
south Texas this afternoon. With temperatures reaching the lower
to mid 90s across most of the CWA today...relative humidity values
will fall below 20 percent across most of deep south Texas except
across the coastal sections. However...20 foot winds will remain
below 15 knots across the area this afternoon except along the
lower Texas coast where RH values will be higher. According to the
Texas A&M Forest Service (TFS)...fuels are not cured across the
area but are transitioning green. The latest TFS forecast fire
danger map indicates moderate to high fire danger across eastern
portions of deep south Texas today so will issue a fire danger
statement for all of the CWA for this afternoon except for the
coastal sections of the coastal counties.



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