Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 191145 AAA

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
545 AM CST Tue Feb 19 2019

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


.AVIATION...Low clouds with light rain and mist continue across
CWA early this morning. Ceilings range 300 ft at BRO and HRL to
near 700 ft across the northern and western portions of deep south
Texas. Visibilities range near 3 SM with light rain/mist at PIL
to near 6 SM with light rain/mist at MFE. Expect LIFR to IFR
conditions across the Rio Grande valley the rest of this morning
as the coastal low across the western Gulf of Mexico continues to
provide overrunning conditions across the lower Texas coast.
Ceilings and visibilities will be low/reduced with light
rain/drizzle/mist across the eastern portions of the CWA through
late this morning. MVFR conditions are expected this afternoon
into the early evening hours before IFR to LIFR conditions return
late in the period.


.PREV DISCUSSION... /issued 354 AM CST Tue Feb 19 2019/

SHORT TERM (Today through Wednesday): A coastal low with a stalled
frontal boundary across the western Gulf of Mexico continues to
provide overrunning conditions across the lower Texas coast this
morning. Drizzle, fog and areas of light rain are expected to
continue this morning as the low moves further north, dragging the
frontal boundary back toward the deep south Texas as a warm front.
Light rain and drizzle will diminish briefly this afternoon in the
wake of the warm front. High temperatures today will be a challenge
with weak warm air advection and some breaks in the cloud cover
possible, especially near the coast. Will lean towards the warmer
GFS guidance as the NAM is too cool and usually does not perform
well in return flow situations. Highs today should reach the mid to
upper 60s to around 70 in the lower Valley. As the surface low lifts
northeast this afternoon, the boundary moves back southeast as a
weak cold front late this evening. Rain chances return this evening
into tonight with the weak cold front. Low temperatures tonight will
range from the lower 50s across the northern ranchlands and upper
50s near the coast. Rain chances linger over the eastern portions of
the CWA on Wednesday with high temperatures in the low 60s near the
coast to the lower 70s across the west.

LONG TERM (Wednesday Night through Monday): A series of 500 mb
troughs over the western and central portion of the country will
maintain a southwesterly 500 mb flow over the RGV and the TX
coastline at midweek. At the surface, coastal troffing will linger
near the lower TX coastline Wed Night into Thurs which will
maintain a persistent chance of light rain/drizzle through Thurs.
by late Thurs/Fri a strong closed 500 mb low will dig into the
Desert SW region on Fri. This will allow the lower TX coastal
troffing to finally weaken and shift northwards away from the
region. This will allow lower pops to prevail into Fri. The
western closed 500 mb low will then shift eastwards into the TX/OK
Panhandle region by early Sat. As this closed low lifts more to
the NE late Sat, it will pull a cold front through the region Sat
evening/night bumping up pops a bit. The old cold front will
likely stall just south and southeast of the RGV over the western
Gulf of Mex. In addition to this, some better moisture values will
pool just south of the RGV. MSL fields from the ECMWF/GFS models
indicate that there could some weak surface troffing once again
near the lower TX coastline this weekend which may maintain some
lingering rain chcs near the lower TX coastline and just offshore
for both Sat/Sun.

Enough CAPE may pool ahead of the next cold front on Sat to
provide enough instability for some isold t-storms. Will include a
mention of this in the morning update.

The 500 mb fields from both the ECMWF and the GFS models are in
pretty good agreement through Day 7/8. Run to run consistency with
both of the longer range models are also in good agreement for
both temps and pops. Will go close to a model consensus throughout
the longer range period.

Overall forecast confidence remains above average this morning due
to the better model agreement.

MARINE (Today through Wednesday): Hazardous marine conditions will
continue this morning as a coastal low moves north along the lower
Texas coast. High pressure builds across the western Gulf tonight
into Wednesday morning, briefly allowing winds to decrease and seas
to subside. A Small Craft Advisory is in effect for the Gulf waters
until noon today and may need to be extended into the afternoon.
Otherwise, Exercise Caution conditions likely tonight and Wednesday
due to elevated winds and seas.

Wednesday Night through Saturday Night: The coastal surface
troffing near the lower TX coastline around midweek will maintain
a fairly strong PGF. This will keep the Gulf winds and seas near
SCEC/SCA levels Wed Night. The PGF will then weaken Thurs and Fri
allowing the surface winds to shift around from the E-SE. As the
next cold front approaches the lower TX coastline on Sat, the PGF
will then re-strengthen possibly pushing the Gulf conditions up
close to SCA levels late in the CWF period.


GM...Small Craft Advisory until noon CST today for GMZ150-155-170-175.



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