Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 231603 AAB

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
1103 AM CDT Fri Jun 23 2017

.DISCUSSION...Did an update this morning to tweak heat numbers
valleywide. Dewpoint temps still higher than forecast, so had to
bump those numbers upwards slightly. This bring a wider area of
115 Heat Index values along the Rio Grande, and Brings Index
values up to advisory criteria in the northern Ranchlands. Have
expanded Heat Advisory into all zones, along with updated zone
forecast. Please limit all outdoor exposure through the afternoon!


.PREV DISCUSSION... /issued 542 AM CDT Fri Jun 23 2017/

DISCUSSION...Updated for latest aviation discussion below.

AVIATION...MVFR is attempting to sneak into the Rio Grande Valley
but full VFR is anticipated today as surface winds become breezy
and higher cloudiness develops. A return to MVFR is anticipated
tonight as clouds thicken and lower as surface winds diminish to
light levels.

PREV DISCUSSION... /issued 305 AM CDT Fri Jun 23 2017/

SHORT TERM (Today through Saturday): The main concern in the short
term portion of the forecast continues to be heat. A Heat Advisory
remains in effect for Cameron, Willacy, Hidalgo, and Starr Counties
for a handful of hours this afternoon due to the combination of hot
high temperatures and relative humidity percentages. The other
significant development in this portion of the forecast will be
isolated to scattered showers and thunderstorms that are anticipated
late tonight through Saturday as broad 500 mb low pressure forms and
persists over the western Gulf of Mexico.

LONG TERM (Saturday Night through Thursday): The forecast period
begins with a broad 500 mb trough over the upper Midwest with
anchoring 500 mb ridges centered over northwest Mexico and Florida
along with a mid level weakness over the western Gulf of Mexico.
A northward extension of the ridge over northwest Mexico into the
Pacific Northwest will gradually move east while deeper troughing
develops over the the eastern Great Lakes. Deeper moisture steady
increases with precipitable water values forecast to be around two
inches near the coast and near an inch and a half inland. The
combination of the mid level weakness and abundant moisture will
support a chance of showers and thunderstorms through the period.
Some of this activity will be diurnally driven sea breeze
convection, but higher moisture moving north along the coast from
the southwest Gulf will provide late night and early morning
convection. Near normal temperatures expected to continue through
the forecast period due to the increase in cloud cover and rain

MARINE (Now through Saturday): Buoy 42020 reported south winds
around 23 knots gusting to around 27 knots with seas of 7.5 feet
with a period of 7 seconds at 02 CDT/07 UTC. Small Craft Advisories
are in effect along the Lower Texas Coast for today due to a
combination of strong winds and leftover swell from Tropical Storm
Cindy. Marine conditions will improve tonight through Saturday with
more moderate winds and seas expected.

Saturday Night through Tuesday Night: Light to moderate east to
southeast winds and low to moderate seas will prevail through the
period. Showers and thunderstorms will be possible at times across
the lower Texas coast waters through Tuesday night.


TX...Heat Advisory until 5 PM CDT this afternoon for TXZ248>257.

GM...Small Craft Advisory for winds until 7 PM CDT this evening for

     Small Craft Advisory until 1 PM CDT this afternoon for GMZ150-



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