Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 260621 AAB
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
121 AM CDT Mon Jun 26 2017

.DISCUSSION...Updated for latest /06z/aviation discussion below.

&&

.AVIATION...The relatively wet forecast continues today as Rio
Grande Valley remains parked between the remaining hot
southwestern U.S. upper level ridge and a flatter ridge across the
eastern Gulf and Florida. Fairly deep moisture rolling across the
now summer-warm Gulf (sea surface temperatures in the mid 80s) in
low level easterly flow is setting off late night scattered
showers and perhaps a few thunderstorms over the Gulf, and
typically some of these survive moving over the slightly cooler
land, with Brownsville and perhaps Harlingen/Valley seeing some of
the action before daybreak.

For this reason, have added MVFR ceiling restrictions along with
the VCSH to Brownsville before sunrise, but held off at Harlingen
for now (though will have to monitor each for both ceiling and
potential brief visibility restrictions in quick downpours).
McAllen/Miller should remain dry through at least sunrise, as
deepening easterly rather than southeast flow will tend to favor
bands weakening before reaching the mid Valley.

For the daylight hours, previous forecast covered the timing of
convective onset well and followed this approach, introducing
thunder at Brownsville/Harlingen by 9/10 AM and McAllen by noon/1
PM. With even deeper moisture in place and fact that all terminals
received measurable rain (over 1 inch at both Harlingen and
Brownsville), went with TEMPO groups for late morning through mid
afternoon (from east to west) with IFR visibilty in thunder, then
tailed back to PROB30 for late afternoon with leftover boundaries
and worked-over areas making specifics more difficult. Expect an
evening break in all areas, but perhaps not for long toward the
coast where PROB30 was reintroduced with as time height sections
increase moisture and continued easterly flow over the warm waters
may quickly redevelop showers soon after sunset which will move
onshore sooner than early this morning.

Ceilings will flirt between high MVFR and low VFR with the MVFR
conditions during the heavier showers or thunderstorms.
52/BSG

&&

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

$$

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