Area Forecast Discussion
Issued by NWS Brownsville, TX

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682
FXUS64 KBRO 270156 AAB
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
856 PM CDT Mon Jun 26 2017

.DISCUSSION...As the daytime convection dissipates with the
waning daytime heating will go ahead and make a few updates to
the pop and sky grids. Slight chances will be maintain inland much
of the evening and overnight period but will keep chance pops
right along the immediate coastal areas and offshore with a low
pressure surface trough present. Abundant tropical moisture to
converge along this boundary allowing for additional shower
development overnight. Latest NAM and Hi-res models suggest the
Gulf convection to move towards the coast by sunrise and inland
after sunrise.

&&

.PREV DISCUSSION... /issued 636 PM CDT Mon Jun 26 2017/

DISCUSSION...Updated for latest aviation discussion below.

AVIATION...Convection is not currently impacting the air
terminals with isolated to scattered convection continuing to
slowly dissipate as daytime heating wanes. Sufficient moisture and
weak low pressure in the mid and upper level of the atmosphere
will maintain at least some chance of showers developing through
the night with mainly VFR conditions. Showers are expected to
increase over the coastal waters overnight and move inland around
sunrise with additional showers and thunderstorms developing
Tuesday morning and afternoon. Mainly VFR conditions with brief
short-lived MVFR in and around the showers and thunderstorms.
Light winds overnight become light easterly 10 knots or less
Tuesday.

PREV DISCUSSION... /issued 251 PM CDT Mon Jun 26 2017/

SHORT TERM (Tonight through Tuesday Night): A weakness aloft
persists over the west Gulf, with an inverted trough analyzed at
the surface. Disorganized shower activity will continue across the
CWA through this evening in a deep east flow with rich
subtropical/tropical moisture measuring over two inches on the PW
scale.

As diurnal heating wanes tonight, cloudiness over land should
diminish, with ongoing convection over the Gulf waters. Overnight
low temperatures will be in the mid 70s.

A few showers will drift onshore overnight, but mostly sunny skies
will otherwise start out the day Tuesday. Isolated shower coverage
will increase to scattered or even numerous during the day, but once
again little organization is expected. Garden variety tropical
showers and thunderstorms will be the norm, with partly to mostly
cloudy skies and high temperatures ranging from the mid to upper 80s
to the lower to mid 90s. A quarter to a half inch of rain might be
the average rainfall total for most areas through Tuesday night,
with lower certainty amounts of two to three inches in deeper storms
moving slowly over an area.

Conditions should settle down again Tuesday night with overnight low
temperatures again in the mid 70s under partly cloudy to mostly
clear skies and light east winds. Moisture to the south will again
move up along the coast in the form of coastal/streamer showers.

LONG TERM (Wednesday through Monday): Weak H5 trough remains
trapped between two main ridges into the upcoming weekend,
keeping some instability in the region. At the surface, southeast
flow begins to increase later in the week as a series of storm
system sweeps across the Central Plains. The higher wind speeds
will increase the shearing of daytime CU development, which will
have a harder time developing vertically before being sheared
apart. Thus showers will be more isolated in nature, and any that
do form will not remain in one location very long. Forecast
vertical profile shows that moisture becomes more limited to the
lowest atmosphere, with drier capping aloft holding convection
down further. This will start late Thursday and continue through
the weekend. Lesser cloud cover will also allow temperatures to
begin to return to sweltering, reaching the mid to upper 90s over
the weekend.

MARINE:
Now through Tuesday night: Broad high pressure over the north
Gulf of Mexico will support light to moderate east winds and low
to moderate seas through Tuesday. Slightly higher winds and seas
will develop Tuesday night before southeast winds return on
Wednesday. A weakness in the upper pattern above the west Gulf
will support scattered to numerous showers and thunderstorms
through Tuesday night.

Wednesday through Friday: Increasing southeast flow between
dominant summertime Gulf ridge and storm systems sweeping across
the plains will begin to cause more treacherous waters late in the
week. Southeast winds will increase to near 20 knots by Friday,
causing wave heights to increase from around 3 feet Wednesday to
near 6 feet on Friday.

&&

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

$$

This product is also available on the web at:
HTTP://WEATHER.GOV/RGV

59...short term
58...long term



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