Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 210009 AAA

Area Forecast Discussion...UPDATED
National Weather Service BROWNSVILLE TX
709 PM CDT FRI MAY 20 2016

.DISCUSSION...With the exit stage right (finally) of the short
wave energy which has created pesky convection the past couple of
days, and leading to a building 500 mb ridge across northern
Mexico extending into south and central Texas as we move into
Saturday and Saturday night, the focus for any rain shifts to the
sea breeze. For this reason, as well as the lack of heating behind
the remnant of the `front` that kept the rio grande plains
generally in the 70s today under a low overcast sky, have pulled
the rain chances back to silent 10 percent for the overnight on
land. Did retain an isolate mention over the Gulf waters with sea
surface temperatures near 80 and possibility for some instability

For Saturday, the combination of just enough moisture remaining in
the column (precipitable water in the 1.8 inch range) and surface
winds just light enough, especially early, to be conducive to sea
breeze enhancement, have oriented rain chances toward the coast
(but not at the beach) during the late morning into noon or so,
then expanded west as currently forecast to the remainder of the
area but still only at a 20 percent "isolated" mention. With sea
breeze enhanced east-southeast flow pushing the marine layer
inland, removed mentionable rain from the Gulf and coastline,
mainly to U.S. 77, after 1 PM. With 500 mb ridge continuing to
build Saturday night, elected to remove mentionable rain chances.
The Sierra Madre May try to go...a little bit, but activity should
remained pinned out there west of the RGV. 52/bsg


.AVIATION...current forecast in good shape overall for the first
18 hours. GFS-20 sounding data don`t lock in a solid low MVFR to
IFR ceiling, but recent trends as well as light enough east winds
along what`s left of the front see no reason why a period of IFR
won`t set up at all three airports sometime after midnight. As
for Saturday, raised the ceiling to VFR and scattered out clouds,
except a mention for TEMPO at the Lower Valley terminals, during
the afternoon with a pickup in east-southeast winds. Due to the
20 percent rain chances, elected to leave out precipitation
mention but this may need to be addressed in later forecasts,
especially for KHRL and KBRO.


.PREV DISCUSSION... /issued 250 PM CDT FRI MAY 20 2016/

SHORT TERM (Now through Saturday Night):Upper level Ridge will
build across the S TX region during the short term forecast with a
weak warm front gradually lifting northward across Deep South
Texas while it gets wash out. Sea breeze developing today is
allowing for isolated showers and thunderstorms to continue along
the sea breeze near the Lower Texas Coast this afternoon. A light
East to Southeast flow across the area will prevail through the
short term with lingering moisture will continue to enhance more
showers and thunderstorms Saturday and Sunday. Rainfall
accumulations will range between a half an inch with higher
amounts of 1 inch possible mainly over the lower valley. Lingering
moisture over the region east of the Sierra Madre will enhance
showers and thunderstorms along the mountains and the western
counties through the night. High temperatures will be in the mid
to upper 80s and near the 90s. Low temperatures will be ranging
between the mid to upper 70s.

LONG TERM (Sunday through Friday):12z model suite in good
agreement with the medium range mid level pattern. A somewhat
quiet and dry pattern to dominate much of the local long term
package with the next chance of rain by the end of next work week.
A high latitude ridge will extend from Central Canada to Northern
Mexico with large troughs dominating the West and East Coast.
Increasing temperatures and lower chance of rain to prevail over
Deep South Texas Sunday through Wednesday as the ridge axis slowly
moves east. Mid level southwest flow increasing late in the week
with upper air impulses traversing Northern Mexico and South
Texas. Any of these implues could combine with increasing moisture
for daytime or overnight convection. temperatures to show a
gradual increase to early Summer readings as the ridge builds.
Tuesday- Thursday 850mb temps range from 22-25C this should bump
highs in the 90-101 range if not hotter in the Mid and Upper
Valley. A moderate southerly overnight will keep minimums elevated
in the mid to upper 70s which remains above normal for mid/late
May. GFS and EC temperatures guidance are within reason and going
forecast continues to utilize a blend of these solutions with some
minor adjustments on the higher end middle of next week. One thing
to mention dew points remain a little elevated as the south winds
increase mid week. This should result in high heat indices
possibly exceeding 105 degrees in some locations. This will have
to be monitored especially if temperatures are warmer than

MARINE (Now through Saturday Night): Weak surface ridging will
remain in control over the western Gulf of Mex through Saturday.
This will maintain a light to moderate e-se surface flow across
the lower TX Bay and Gulf waters. No SCA conditions expected
through Saturday night. Sunday through Wednesday...onshore flow
and seas will experience a gradual increase through next week as
the pressure gradient strengthens. Strongest winds are expected
Monday night through Wednesday with periods of small craft
advisory conditions.


.BRO Watches/Warnings/Advisories...


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