Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 220555 AAB

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
1255 AM CDT Wed Mar 22 2017

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


.AVIATION...Mostly clear skies and light southeast winds prevail
across Deep South Texas early this morning. VFR conditions
expected to continue for the next 24 hours with surface high
pressure in place. However, guidance continues to suggest very
brief excursions down to MVFR ceilings around dawn, but will hold
off on the mention of a TEMPO due to uncertainty. South-southeast
winds will become moderate and gusty later this morning into the
afternoon due to the local gradient. Southeast winds will
gradually diminish after sunset this evening.


.PREV DISCUSSION... /issued 632 PM CDT Tue Mar 21 2017/

DISCUSSION...Only change this evening was to add patchy fog from
08-14Z later tonight into early tomorrow morning for the Northern
Ranchlands. This is congruent with neighboring office and trends
of recent nights in addition to being suggested by MOS guidance.
Updated text products already sent.

DISCUSSION...Updated for latest aviation discussion below.

AVIATION...Still anticipating primarily VFR for the next 24
hours, with upstream mid-level ridging and Gulf high pressure
still dominant. Some of the guidance hinting at very brief
excursions down to MVFR CIG`s in the hours around dawn Wednesday,
with the base of an isothermal layer still showing up around
015-025 on the prog soundings. Will just insert a SCT deck for now
due to uncertainty. Lighter southeast winds overnight will become
moderate and gusty once again by late morning with SCT-BKN low CU
along the coast, but generally above 3 kft.

PREV DISCUSSION... /issued 257 PM CDT Tue Mar 21 2017/

SHORT TERM (Tonight through Wednesday Night): The short term
will be rather quiet, though temps. will run several degrees or
more above normal. Mid level ridging will lie upstream, with high
pressure over the Gulf, supporting a typical moderate south
southeast wind across the area. The forecast sounding at BRO
suggests that low level moisture will recover slightly, but dew
points are still forecast to remain in the mid 60s. Low cloudiness
will develop along the coast to mid valley tonight, but will mix
out through mid morning as winds pick up from light to moderate
and gusty, a bit stronger than today due to a slightly enhanced
pressure gradient.

LONG TERM (Thursday through Tuesday): Midlevel Low currently
moving ashore on the West Coast will close off and sweep across
the central and southern Plains Friday morning. The very southern
edge of the trough will pass just north of the region, pushing
over the H5 ridge. Weak front will drift into south Texas, but
will generally stall to the north. There may be enough instability
aloft and forcing near the sfc to spark a few showers right around
noontime for the northern ranchlands, but even these would be
highly isolated, and would be moving quickly to the northeast. H5
ridge returns briefly Saturday before the next weaker trough
sweeping across Texas Sunday afternoon. While this feature passes,
surface low pressure moves across the Texas Panhandle into
Oklahoma. This will tighten the gradient locally, producing
stronger southerly winds Sunday and continuing again Monday. With
minimal cloud cover or cooler airmasses approaching, temperatures
will again continue to gradually reach further into the upper 80s
and 90s into early next week.

Now through Wednesday night: Gulf high pressure will dominate
through Wednesday, with moderate southeast winds and moderate
seas. Lower pressure developing in the plains Wednesday night will
result in a tighter pressure gradient, with southeast winds
ramping up to fresh by Thursday. Hence, small craft should
exercise caution conditions will be possible Wednesday night.

Thursday through Sunday: Most of the extended forecast will remain
breezy as a couple areas of low pressure sweep through Texas. The
first one will move through Thursday and stall to the north
Friday. This will keep winds elevated both days, with higher winds
expected Thursday night. Higher winds will push wave heights to 6
to 8 feet. Small Craft Advisories are likely for both days. A
lull between systems arrives on Saturday, with southerly flow
dropping to around 10 knots through the day, allowing seas to
relax to 4 to 5 feet. Further decreases will end by Sunday morning
as the next surface low wraps up to the north, bringing winds back
up to around 20 knots, with seas reach 6 to 8 feet again.




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