Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 210622 AAB

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
122 AM CDT Thu Sep 21 2017

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


.AVIATION...Low level moisture will continue to increase across
the region overnight with onshore flow bringing the small chances
for streamer. Meanwhile, occasional low MVFR cigs will pass across
Deep South Texas through the early morning hours. Otherwise, VFR
conditions will be noted through the afternoon, with scattered to
widely scattered SHRA possible. Winds will be gusty from the
southeast once again today.


.PREV DISCUSSION... /issued 641 PM CDT Wed Sep 20 2017/

DISCUSSION...Updated for latest aviation discussion below.

AVIATION...Daytime CU field breaking up currently. Dense field of
CirroCU moving in from the southwest will continue to overspread
the region through the night. This should continue to limit llvl
CU production through sunrise. Daytime CU returns tomorrow, and is
expected to be more numerous. Midlevel shortwave may help to spark
widely scattered showers during the late morning and early
afternoon along the seabreeze. Seabreeze convection will also
depend on strength of llvl winds, as speeds will be right near the
15kt threshold for productive seabreeze formation.

PREV DISCUSSION... /issued 308 PM CDT Wed Sep 20 2017/

SHORT TERM (Tonight through Thursday night): The broad mid-level
high pressure area over Texas remains intact while a weak upper
level (300mb)shortwave, evident in water vapor loops over Coahuila
Mexico, moves across South central Texas Thursday. This may allow
for a few more showers or a thunderstorm to develop with possible
enhancement along the seabreeze. Moisture values remain high,
pwats 2"+, and GFS/ECMWF shows slightly deeper moisture as the
shortwave passes nearby. GFS guidance continues to be on the low
side of consensus with ECMWF on the high end. will continue to
show a blend of the model output. Any of thunderstorms that do
develop could produce heavy rainfall. Temperatures will continue
to be above normal with warm muggy nights in the mid to upper 70
and daytime highs in the 90`s to lower 100s.

LONG TERM (Friday through Wednesday): By the end of the week, the
pattern will include a deep 500mb trough digging into the
Southwest U.S. with broad ridging east of the Great Plains and
over the Midwest. Models continue to indicate a mid-level low
developing over the central Gulf this weekend, but we will remain
in general ridging with strong subsidence and dry air aloft. As
we move into next week the trough is expected to move a little bit
closer into West Texas with deeper tropical moisture moving
northward into our area, so precipitation chances may increase
Tuesday through Thursday if any impulses can move overhead.
Decided to make only little changes to the forecast and have kept
20-30% PoPs each day due to model discrepancies towards the latter
half of the forecast next week. Temperatures will remain above
normal through this weekend with near-normal temperatures next

MARINE (Tonight through Thursday night): Light to moderate winds
and low sea regime is expected to persist through Thursday night
with weak high pressure interacting with lower pressure over NW

Friday through Wednesday: Light to moderate southeast winds will
likely continue for much of the long term period with low seas of
2 to 4 feet as high surface high pressure remains over the
northern Gulf.




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