Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 192357 AAA
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service BROWNSVILLE TX
657 PM CDT TUE JUL 19 2016

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

&&

.AVIATION...A few passing clouds with moderate east winds prevail
across Deep South Texas this evening. VFR conditions expected to
continue through the next 24 hours. Winds will become light and
variable after sunset this evening. A few clouds tonight will
affect the skies overhead. Isolated showers and thunderstorms will
develop along the lower Texas coast and move inland Wednesday morning
into the afternoon hours. Confidence is not high enough to include
anymore than VCSH in this TAF cycle. Light east-southeast winds
overnight will become easterly on Wednesday with gusts up to 20
knots in the afternoon.

&&

.PREV DISCUSSION... /issued 320 PM CDT TUE JUL 19 2016/

SHORT TERM (Tonight through Wednesday Night):Fairly easy forecast for
the next 48 hours, as weak wave that helped kick off isolated to
scattered mainly inland showers today exits stage left, leaving the
broad 500 mb ridge to dominate from the Central Plains to the
Valley. Today`s deeper moisture gradually dries up from east to
west mainly in the 850 to 300 mb layer beginning tonight and really
kicking in Wednesday afternoon and most of Wednesday night, before
mid and high level moisture increases ahead of a weak inverted
upper level trough and associated thin plume of tropical moisture
headed toward the mouth of the Rio Grande by daybreak Thursday,
which has been well advertised by the GFS and to some degree the
ECMWF the past few runs.

For the sensible weather, the march of the sea breeze and
*northeast* winds behind it have killed off convection for the
coastal counties and by late afternoon Hidalgo and Brooks, and have
removed rain chances accordingly there.  Removed mention of thunder
on the whole as well as showers have been cruising along with
limited vertical extent and see no reason for this to change.

For the overnight, quick clearing with rapidly diminishing winds
from the coast to the Rio Grande Plains.  Low decks formed up this
morning near Hebbronville, but not enough confidence in areal
coverage to modify sky cover from mostly clear at this point.  With
the mainly clear skies and calm winds temperatures should fall to
relatively comfortable levels, similar to this morning.  Harlingen
was 74 and many ranchland sites in the mid 70s so followed this
trend, keeping the McAllen heat island among the warmest.

There`s still enough residual moisture around to argue for some
mention of rain, isolated at best, from the Gulf toward Laguna
Madre around daybreak. As for Wednesday, the rapid drying should
overtake any early streamers and "jump" sea breeze convection
inland, so removed rain chances for the lower/mid Valley by 1 PM
and for all but the Rio Grande Plains after 4 PM. Even then,
confidence not all that high for much rain and expect coverage and
amounts to be less than today. For this reason, elected to nudge
temperatures up a degree or two in all areas, which brings McAllen
back to the century mark for what would be the 22nd day in a row,
all alone in 4th place all time for such a streak dating back to
1961.

LONG TERM (Thursday through Tuesday): A strong H5 upper level
ridge over the mid section of the U.S. will just begin shifting
back to the west. However...the overall synoptic patter will
continue to be characterized by deep east to southeast flow.
Within this flow regime...several impulses of deeper moisture will
continue to be steered westward towards the region. Coupled with
both upper and lower level troughs...although somewhat weak in
nature...the pattern will bring isolated to scattered showers and
isolated thunderstorms to the coastal and inland areas through
much of the period. Precipiation will still likely be more hit
and miss in nature...with sea breeze enhancement during the
afternoons. As far as temperatures go...values will be closer to
normal...but may still be slightly above average.

MARINE:

Today through Wednesday: All quiet to start the period with light
winds and slight seas for the evening. However, persistent
easterly fetch below the elongated surface ridge from southeast
Texas through Georgia beginning to build swell and eventually seas
toward 3 to 4 feet, highest in the offshore waters beyond 40 nm.
Wavewatch indicated some 5 foot seas in the southeast corner but
not too bullish - though this has been the case for a few runs
now. Other than the seas, winds will remain light, no higher than
12 knots or so in the waters beyond 20 nm and briefly 15 knots
with afternoon sea breeze enhancement over the Laguna Madre.

Thursday through Sunday:

The 3 to 4 feet swells will continue through the end of the week
as a broad easterly flow regime remains in place. This will keep
seas generally light to moderate. However...winds will remain
light...generally less than 15 knots. Nocturnal and early morning
showers as well as an occasional thunderstorm.

&&

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

$$

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