Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 231107 AAA
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service BROWNSVILLE TX
607 AM CDT SAT JUL 23 2016

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

&&

.AVIATION...Isolated to scattered showers are again moving north
along the coast this morning, but conditions remain VFR with clear
skies and very light winds at the TAF sites. The streamer showers
will fade into the morning daylight. Plentiful low level moisture
will continue along the coast, however, with PWAT forecast to be
around 2.0 inches at BRO around mid day. Guidance suggests a late
morning sea breeze with winds veering and becoming moderate and
gusty. The breeze will progress slowly west through the early
afternoon before reaching the mid valley. Guidance is not bullish
on significant PoP, and have therefore not included any explicitly
in this TAF set, but it will be hard to avoid a few showers around
the area, which will necessarily be hit and miss and could result
in brief lower ceilings and moderate downpours.

&&

.PREV DISCUSSION... /issued 405 AM CDT SAT JUL 23 2016/

SHORT TERM (Now through Sunday)...A fairly expansive mid level
height center positioned over the southern high plains and extending
from southern California to the Mississippi River will provide a
measure of stability and persistence to the local forecast. Surface
high pressure covers the southeast United States and the north Gulf
of Mexico. Little significant change in the weather is on the
immediate horizon, and fair skies with an occasional smattering of
low clouds along with light to moderate southeast winds and warmer
than normal temperatures will dominate conditions through the short
term. Afternoon heat index values from 103 to 108 degrees will be
possible in some areas like Hidalgo and Starr Counties, but lower
100 to 105 degree heat index values will be more common over much
of the CWA. The onshore flow will keep dew points in the 70s, with
PWAT values above average in the upper quartile of the one to two
inch increment. Nonetheless, PoP will remain mostly in the slight or
isolated category. Actually went a little higher than model guidance
across sea breeze territory in order to keep mentionable precip in
parts of the forecast, since we`ve been seeing some production out
of the sea breeze, despite being hard to pinpoint specific locales.
May also see isolated coastal showers overnight, which has been a
recurring feature. As previously suggested, conditions will continue
to be similar to what we`ve been seeing the last few days.

LONG TERM (Sunday Night through Friday):For the most part the long
term will be keying on a change in the mid and upper level
features across Texas mainly Tuesday through the end of next work
week. Models continue evolving towards settling on an amplified
ridge in the west with another weaker ridge across the Southeast
states with troughs over the Midwest and across Texas. Main
challenge for the period will be rain chances and areal coverage
with differences on the moisture fields between the drier GFS and
the slightly wetter ECMWF. With the approach of an westward moving
inverted trough Tuesday we will see some increase in moisture
however GFS is having a difficult time with day to day consistency
in depth and content. ECMWF usually has a wet bias and is not
disappointing in this pattern with some pops as much 30 points
higher Tuesday and Thursday. Not totally convinced it will rain
everywhere and everyday so the forecast will not be zero but do
not expect widespread rainfall either. Will use a blend of of GFS
and ECMWF trending on a drier bias since we have been dry and we
are in our climatological driest Summer period. The other slight
change in the pattern will be that day time winds to increase with
breezing conditions developing Tue-Thu. Lee side trough
strengthens as the mid level ridge shifts east tightening the low
level gradient mid week. The only element that wont see much
variation will be the temperatures. Even with the ridge not
overhead maxes should not see change with mid 90s to lower 100`s.
GFS is on the higher end with lower rain chances but the ECMWF is
only 1-3 degrees lower on a few select days. If anything overnight
lows may be warmer as the winds increase and may not be calm
overnight as has been the case the last several nights which allow
for minimums to fall closer to the dewpoint. In any case, its
Summer and it will continue to be hot during the day and sultry at
night.

MARINE:Now through Sunday...No marine headlines are expected
through the period. Broad high pressure across the southeast
CONUS and northern Gulf of Mexico will produce a weak pressure
gradient and mainly light to moderate southeast to south winds and
low to moderate seas. Isolated showers may occasionally develop
and move north along the coast.

Sunday night Wednesday: The pressure gradient is expected to
tighten gradually next week with slightly stronger southeasterly
winds and a slow steady rise in seas by the end of the period. The
upper ridge over the Central Plains breaks down and moves west.
This will allow for slightly deeper lee side troughing to develop
across Northeast Mexico. Not anticipated small craft advisory
conditions however marginal conditions may warrant exercise
caution winds Tuesday through Thursday during the daytime across
the Laguna and overnight over the Gulf waters.

&&

.BRO Watches/Warnings/Advisories...
TX...None.
GM...None.
&&

$$

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