Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 271706 AAB
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
1206 PM CDT Sat May 27 2017

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

&&

.AVIATION...High pressure is still in control over the Gulf,
interacting with lower pressure upstream to produce breezy and
gusty south southeast winds. Ceilings have mixed out, but the base
of a deep isothermal layer/cap has maintained scattered low
clouds below 3 kft. High clouds from the south side of a jet
streak are moving over south Texas and will also be in the mix
the next 24 hours. MVFR ceilings will be back this evening with
ample low level moisture and light to moderate winds, and will
persist into mid Sunday morning when moderate to breezy winds
develop and again mix out the boundary layer.

&&

.PREV DISCUSSION... /issued 559 AM CDT Sat May 27 2017/

DISCUSSION...Updated for latest aviation discussion below.

AVIATION...Low clouds will continue to bring MVFR cigs through
the mid morning before conditions improve back to VFR. High clouds
will prevail across the region today, with gusty south to
southeast winds in place. Ample low level moisture will bring
another round of MVFR cigs Saturday night.

PREV DISCUSSION... /issued 415 AM CDT Sat May 27 2017/

SHORT TERM (Now through Sunday): Subtropical ridging will be the
dominate weather feature through the next 24 to 36 hours. At the
surface this morning, high dewpoints in the mid to upper 70s will
bring extremely humid conditons with there being enough moisture for
patchy fog or haze across portions of the Mid to Lower Valley. This
fog or mist is not expected to last long as winds should come up
again rather quickly this morning as the surface pressure gradient
remains fairly strong. As such, it will be another breezy day across
the RGV with speeds similar or maybe a smidge lower than previous
days.

Meanwhile, the main concern today will be high temperatures once
again several degrees above normal. Readings will be in the mid to
upper 90s across near/across the I-69E corridor with highs near or
or a few degrees above 100 along and west of I-69C. The warm
temperatures, combined with the high dewpoints, will create heat
index values from 105 to 110 across much of Deep South Texas.
However, even higher values from 110 to 115 will be noted across
portion of Hidalgo and Starr counties. Will issue a Heat Advisory
for these two counties, although there is still some uncertainty if
other counties will need to be added. It should be noted that models
are suggesting a thicker layer of high clouds across the region
today which would help hold down temps.

Heading into Sunday, the subtropical ridge breaks down and shifts
back across the Eastern Gulf. This should help keep temperatures a
couple of degrees cooler on Sunday. Meanwhile, although the dry
forecast should continue through the day, a cold front will be
meandering towards south across Texas. However, any rain chances
will likely hold off until just beyond this period.

LONG TERM (Sunday Night through Friday): An unsettled weather
pattern continues to be anticipated during the long term portion
of the forecast. 500 mb high pressure centered over Florida will
shift even farther east to the Atlantic Ocean as deep 500 mb low
pressure transitions for the Pacific Ocean to the southern portion
of the West Coast of the United States. This pattern will place
Deep South Texas and the Rio Grande Valley in a favorable position
for convection, and indeed, generally isolated to scattered
showers and thunderstorms are forecast for the BRO CWFA. The most
favorable time period for rainfall appears to be Monday afternoon
and evening, as a small mid-level area of low pressure passes
directly over the BRO CWFA, possibly initiating a mesoscale
convective system that will affect the entire area. Temperatures
are likely to be close to near normal levels given the expected
cloud coverage and opportunity for rainfall.

MARINE (Now through Sunday): Current conditions at Buoy 42020 at
2AM show SSE winds round 15 knots with gusts to near 19 knots. Seas
have been holding steady with 4 to 5 ft waves. The pressure gradient
will be strong again today with surface high pressure dominating the
Eastern Gulf of Mexico. The high pressure will interact with low
pressure across the Mexican Plateau and the Panhandles region. SSE
winds will increase across the Laguna Madre later this morning and
through the afternoon and a Small Craft Advisory for winds will be
issued. Winds will breezy across the Gulf Waters east of Padre
Island but should stay below advisory level with seas remaining
steady near 5 feet. The pressure gradient will begin to relax
Saturday evening into Sunday the ridge breaks down a bit and allows
a cold front to move into Central Texas. However, winds will still
be in the SCEC range of about 15 to 19 knots from the SE.

Sunday Night through Friday: Moderate winds and seas will prevail
along the Lower Texas Coast during the entire forecast period with
high pressure over the Gulf of Mexico interacting with lower
pressure over inland Mexico. Small Craft Exercise Caution may need
to be regularly issued due to winds and/or seas.

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...Heat Advisory until 6 PM CDT this evening for TXZ252-253.

GM...Small Craft Advisory for winds until 6 PM CDT this evening for
     GMZ130-132-135.

&&

$$

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