FXUS64 KBRO 232326 AAA
Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
626 PM CDT Wed May 23 2018
.DISCUSSION...Updated for latest aviation discussion below.
.AVIATION...A few passing low to mid level clouds and light to
moderate southeast winds prevail across deep south Texas this
evening. Will continue to mention VCSH at MFE due to some lingering
showers across the upper Valley. Otherwise, expect VFR conditions
for the next 24 hours due to the relatively dry and stable
airmass in place over the region. However, some brief MVFR
ceilings may develop late tonight into Thursday morning. But will
not mention these potential MVFR ceilings in this TAF cycle.
.PREV DISCUSSION... /issued 256 PM CDT Wed May 23 2018/
SHORT TERM (Tonight through Thursday Night): Daytime heating is
maintaining isold coastal conv this afternoon. Expect these to
diminish later this evening with the loss of the afternoon heating.
However, will maintain some 20 % pops for the early evening hours
mainly across the eastern areas and out over the Marine locations.
As an eastern Pacific 500 mb trough axis digs into the West Coast,
expect the 500 mb ridging over Mexico to steadily build east over
the short term which will in turn steadily stabilize that atms over
the RGV. This will maintain the above normal temps through
Thurs/Thurs Night as the atms moisture levels decrease. Diurnal
heating tomorrow may still fire off some isold conv during the late
morning and afternoon hours. But am not confident enough to include
this in the current forecast wording.
For temps will go close to a persistence forecast as the atms slowly
dries out through the period. The NAM/GFS and ECMWF MOS temps also
stick pretty close to persistence through tomorrow night.
LONG TERM (Friday through Wednesday): The long term begins with
the CWFA squeezed between ridging across much of Mexico and
troughing across the Gulf. This will allow for generally dry
northwesterly flow to persist across the region, which should
limit rainfall chances through the long term period.
Eyes are still on the developing (sub)tropical low across the
western Caribbean Sea. Globals are still showing modest
development eventually by this weekend. With the strong troughing
across the north Gulf, confidence is there that this weakness is
more than enough to keep it on a poleward track toward the central
and eastern U.S. Gulf Coast. The only impact will be subsidence
(clear and hot) conditions through the weekend...and HOT it will
be with a large number of us seeing temperatures warm to near or
above 100 degrees. Overnight lows will remain around average in
MARINE (Tonight through Thursday Night): Surface ridging over the Gulf
of Mexico will maintain a pretty light PGF over the lower TX Bay and
Gulf waters through tomorrow night. Accordingly, fairly light
easterly winds and low seas will continue throughout the short term
with no SCA conditions expected through Thurs Night.
(Friday through Wednesday): Globals have reduced pressure gradient
just a bit over the last 24 hours or so. At this time only light
to perhaps moderate winds are expected this weekend and into
early next week allowing for mostly tranquil marine conditions.
The possibility of a (sub?)TC developing in the Gulf does add
some uncertainty (wave height) by early next week as swells may
begin to increase depending on how strength of the system and how
long it may spend over gulf waters. Based on this, wave height
forecast confidence will be a bit below average until we know more
about the (sub)tropical low evolution.
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