Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 191821

Area Forecast Discussion
National Weather Service BROWNSVILLE TX
121 PM CDT THU MAY 19 2016

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


.AVIATION...A line of convection over the northwest portion
of Deep South Texas will move continue to move E to SE this
afternoon producing moderate rainfall with some ocassional
lightning. This convection will continue to develop into the
RGV later as the boundary approaches in the next few hours.
Can`t uled out a few stronger storms that could develop with
this activity. Included TEMP groups for the best timining
possible for the storms to form near the terminals. MVFR cigs
and visibilities will be possible near convection. expect low
visibility and mvfr cigs overnight with a mix of fog and haze.
conditions improve into Friday after sunrise.


.PREV DISCUSSION... /issued 645 AM CDT THU MAY 19 2016/

DISCUSSION...Updated for latest aviation discussion below.

AVIATION...a mix of low and mid level clouds prevail across deep
south texas this morning. light east to southeast winds continue
at the surface with more moderate winds...20 to 25 knots...between
1000 to 2000 feet. will hold off on a non-convective low level
wind shear at this time. MVFR conditions possible through mid
morning then improving conditions expected through late this
evening. Short term guidance (NAM and HRRR) continue to indicated
some possible convection after 17z as an upper-level impulse
approaches from the west. MVFR ceilings and visibilities will be
possible near convection. Showers and thunderstorms should
diminish late this evening as the upper impulse moves east of the

PREV DISCUSSION... /issued 455 AM CDT THU MAY 19 2016/

SHORT TERM (Now through Friday): The main concerns in the short
term portion of the forecast will be the potential of severe weather
and flash flooding. A quasi-stationary front positioned across the
area, abundant moisture, daytime heating and an upper-level impulse
approaching from the west will provide a good chance of showers and
thunderstorms for today. The Storm Prediction Center has placed all
of deep south Texas in a Slight Risk of severe weather from around
sunrise this morning to around sunrise Friday morning. Strong to
severe thunderstorms, featuring large hail, damaging winds, and
flash flooding, expected to move into the Rio Grande Valley and deep
south Texas from the neighboring Mexico later today. Have included
the weather threats in the forthcoming official forecast.

Rain chances are a little tricky today with the NAM suggesting low
pops and the ECMWF indicating more robust rain chances. Have
discounted the NAM and will lean towards the GFS/ECMWF for pops for
today and tonight. Some convection may also develop along outflow
boundaries or drift south into the northern ranchlands. A Flash
Flood Watch remains in effect for the entire CWA until 7 pm this
evening. Some showers and thunderstorms may linger this evening and

Weak boundary convergence and convection over the higher terrain of
Mexico should provide another round of showers and thunderstorms
across the region on friday. The Storm Prediction Center has all of
deep south Texas in a Marginal Risk of severe weather on Friday.
Strong to severe thunderstorms with large hail, damaging winds, and
flash flooding will be possible once again Friday.

Temperatures will depend on the rainfall and amount of cloud cover.
High temperatures today expected to be in the 80s under mostly
cloudy skies. Low temperatures tonight will be in the 70s. High
temperatures Friday will be in the 80s near the coast and the lower
90s across the west.

LONG TERM (Friday Night through Wednesday): isolated showers and
thunderstorms are forecast from Friday night through Sunday due to
closed 500 mb low pressure over the western United States setting
up a west-southwest to east-northeast mid-level flow over Deep
South Texas and the Rio Grande Valley, with embedded disturbances
flowing within. Drier weather will develop Sunday night and
persist through the remainder of the Long Term forecast period as
the closed low opens up and ejects off to the northeast and a 500
mb ridge of high pressure builds north over the Lone Star State.
Above normal daytime high and overnight low temperatures will
still be the norm.

MARINE (Now through Friday): Buoy 42020 reported Southeast winds
around 10 knots with seas slightly under 3.0 feet with a period
of 4 seconds at 03 CDT/08 UTC. Light to moderate winds and low to
moderate seas will prevail along the lower Texas coast through the
forecast period with weak high pressure over the western Gulf of
Mexico. Small Craft Exercise Caution and Small Craft Advisory are
not likely to be needed.

Friday night through Wednesday: moderate winds and seas will
prevail along the Lower Texas Coast through the period with
surface high pressure in control over the western Gulf of Mexico.
Winds may be strong enough, and seas high enough, to warrant a
Small Craft Exercise Caution and/or Small Craft Advisory from
Monday night through Wednesday for all or portions of the Lower
Texas coastal waters.


.BRO Watches/Warnings/Advisories...
TX...Flash Flood Watch until 7 PM CDT this evening for TXZ248>257.



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