FXUS64 KBRO 192309 AAA

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
609 PM CDT Thu Jul 19 2018

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

.AVIATION...Satellite images and surface observations indicate
clear skies across the CWA early this evening. Expect VFR
conditions to prevail across the Rio Grande valley tonight into
early Fri morning as the 500mb subtropical ridge across the
southwest United States extending into south Texas will continue
to provide subsidence across the area.

.PREV DISCUSSION... /issued 235 PM CDT Thu Jul 19 2018/
SHORT TERM (Tonight through Friday night): Hot and dry conditions
will continue across the CWA Friday as the 500mb subtropical
ridge across the southwest United States will continue to provide
subsidence across deep south Texas tonight through Fri night. Some
low to mid level moisture will move around the southeast
periphery of the upper level ridge towards the area tonight into
Friday. This will provide a few more clouds across the Rio Grande
valley Friday and should keep temperatures from reaching record
highs (100 degrees in Brownsville and 107 degrees in McAllen) Fri
afternoon. Unfortunately...heat index values will likely reach 105
to 110 degrees across most of the area tomorrow with some
isolated areas above 110 degrees.

LONG TERM (Saturday through Thursday): The initial mid level ridge
centered over the southern High Plains and surface high pressure
over the northwest Gulf will persist into the long term. The ridge
will remain firmly in place over the weekend and will extend out
into the northwest and central Gulf. This pattern will block any
significant weather systems from affecting the local area, and will
support continued above normal temperatures both day and night, and
near record daytime high temperatures.

A mid level low will drop slowly south out of the Midwest and into
the southern United States over the weekend and early next week,
ending up over the north Central and north East Gulf Coast,
supporting increased convection there. The low will shift slowly
east along the north Gulf Coast through mid week, elongating to the
southwest as the dominating ridge retreats slightly west. Some
marine convection may begin to develop or move farther south along
the Texas coast as a result. A few extra clouds will be possible,
and isolated showers may develop Tuesday through Thursday, but the
mentionable showers will so far be limited to the marine areas.

In the mean time, look for afternoon heat index values to range
between 105 to 110 degrees, with isolated brief, slightly higher
values. Daily high temperatures will trend higher than normal. This
will help push heat index values higher. There will be a possibility
of a heat advisory each afternoon through the long term.

Tonight through Friday night: Seas were near 2 feet with south to
southwest winds near 10 knots at buoy002 and near 3 feet with
south winds near 10 knots at buoy019 this afternoon. Moderate to
strong south to southeast winds will prevail across the coastal
waters tonight with low pressure across west Texas and high
pressure across the Gulf of Mexico providing a strong pressure
gradient across the lower Texas coast. Will continue to word SCEC
for the Laguna Madre this evening and for the offshore waters
tonight. The pressure gradient will weaken slightly across the
lower Texas coast Friday. Light to moderate south to southeast
winds will prevail across the coastal waters Friday into Fri

Saturday through Tuesday night: Light to moderate south winds and
low to moderate seas will prevail during the long term as high
pressure dominates the northwest Gulf.



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