Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 200511
AFDBRO

Area Forecast Discussion
National Weather Service Brownsville TX
1111 PM CST Sun Nov 19 2017

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

&&

.AVIATION...Cloud cover will be increasing the next 24 hours,
with a digging, positive tilt, mid level short wave trough moving
toward the area from upstream tonight, and moving over the area on
Monday. The combination of upper lift and surface high pressure
shifting east, such that surface winds veer to east and southeast
later on Monday, with a weak return of Gulf moisture, should be
enough to trigger isolated showers during the day. The forecast
sounding at BRO for Monday suggests a continuing inversion in the
lower levels, with a steeper lapse rate aloft, thereby not giving
surface based convection much of a chance. Guidance is not yet
hinting at any significant ceiling reductions along the way, except
for late afternoon MVFR ceilings by the NAM, so will continued with
mainly VFR TAFs for the terminals.

&&

.PREV DISCUSSION... /issued 526 PM CST Sun Nov 19 2017/

DISCUSSION...Updated for latest aviation discussion below.

AVIATION...Cloud cover will be increasing the next 24 hours,
with a mid level short wave trough moving toward the area from
upstream tonight, and moving over the area on Monday. The
combination of upper lift and high pressure shifting east, such
that surface winds veer to east and southeast later on Monday,
with a return of Gulf moisture, should be enough to trigger
isolated showers during the day. Guidance is not yet hinting at
any significant ceiling reductions along the way, so have
continued with VFR TAFs for the terminals.

PREV DISCUSSION... /issued 236 PM CST Sun Nov 19 2017/

SHORT TERM (Now through Monday Night): A very nice, albeit cooler
day across deep south Texas. Winds have been a bit brisk as well,
especially across the valley. Winds will begin to relax a bit as
surface pressure gradient relaxes this afternoon and especially
this evening.

Overnight we`ll likely begin to see some clouds develop as an H5
impulse begins to move across the Big Bend region and eventually
over our neck of the woods tomorrow late morning. Globals are still
pinging POPs with this feature. In fact, moisture seems to be
slightly higher with this impulse than with the cold front that
moved through last night. Even with slightly more moisture the
profile still could be defined as lackluster, which will be the
main limiting factor. Still, felt the signal supported
slight/chance POPs for the valley and offshore.

As for temperatures, around or perhaps even slightly below average
is anticipated for the short term. Eventually, northerly flow will
transition to easterly flow, which will transition into southerly
flow by early Tuesday morning. This will help bounce moisture values
up a tad by early morning Tuesday. Overnight lows Mon PM/Tues AM
will be just a bit warmer with the increase in low level moisture.

LONG TERM (Tuesday through Sunday): The major event in the long
term portion of the forecast will be the approach and passage of a
cold front in association with the development and deepening of a
500 mb trough over the Mississippi Valley and Southeast United
States. Isolated showers are anticipated over the immediate three
coastal counties, with more scattered convection over primarily
the Lower Texas coastal waters, Tuesday night through Wednesday
in association with these surface and mid-level features. The
remainder of the forecast will be dry courtesy of surface and 500
mb high pressure. Temperature-wise, the passage of the cold front
should bring temperatures initially to near normal levels before
they rebound towards the end of the period.

MARINE (Now through Monday night): Conditions will remain hazardous
through this afternoon hours today. In fact, had to extend the SCA
for Laguna Madre through mid afternoon as winds were still enough to
justify the headline (PIL reported 20kt with higher gusts last
hour). Eventually, conditions will improve over the Laguna and near
shore Gulf waters of deep south TX. At the very least, SCEC is
expected through the overnight and into the morning hours on Monday.
Conditions should be much better Monday through the end of the
marine short term period.

Tuesday through Sunday: The passage of a cold front late Tuesday
night or during the pre-dawn hours of Wednesday morning will
produce strong winds and rough seas along the Lower Texas Coast.
Small Craft Advisories are possible for portions or all of the
Lower Texas coastal waters from roughly around sunrise Wednesday
morning to roughly around sunrise Thursday morning. Outside of
this time frame, light to moderate winds and low to moderate seas
are anticipated courtesy of surface high pressure.

&&

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

$$

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19/59


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