Area Forecast Discussion
Issued by NWS Brownsville, TX
FXUS64 KBRO 280553 AAA
Area Forecast Discussion...UPDATED
National Weather Service BROWNSVILLE TX
1253 AM CDT THU JUL 28 2016
.DISCUSSION...Updated for latest aviation discussion below.
.AVIATION...Mid to high clouds will be common through the period
as another upper level disturbance passes by on Thursday with an
increase of moisture. VFR conditions will prevail...with
possible brief MVFR cigs overnight. There could be a few
seabreeze showers or Tstorms during the afternoon hours...however
coverage remains too low to mention in TAF package. Light SE winds
overnight will become more gusty in the afternoon.
.PREV DISCUSSION... /issued 308 PM CDT WED JUL 27 2016/
..SWELTERING HEAT AND LITTLE RAIN INTO EARLY AUGUST...
SHORT TERM (Tonight through Thursday Night): Modest moisture and a
weak low pressure trough over Texas to produce a low chance of
showers and/or thunderstorms Thursday. Atmosphere was not that
efficient in drying out the mid layers as much as the models
suggested. It was dry enough in the Eastern half to keep this region
dry however the western half saw some sprinkles (light showers)and
multi-layered clouds keeping Max temperatures from reaching their
potential. We will likely see similar conditions Thursday but with
slightly higher chances of rain for most locations. Mid level mean
RH is projected in the 60-70 percent range add in the heating,
seabreeze and the slight weakness aloft and you can not rule out
isolated convection. In general, EC/GFS pop guidance has increased
from today`s single digits to near 20 percent with the NAM looking
like an outlier with 30-40 percent pops in the Eastern counties.
Grids will be broad brushed with 20 percent. As for Temperatures,
with plenty of cloud cover expected Overnight lows will likely be a
degree or two warm with Thursday`s highs possibly having another
reprieve with most locations staying just shy of triple
LONG TERM (Friday through Wednesday): July will end as it
started...hot, rain-free, and occasionally breezy especially from
late morning through sunset. In the big picture, dominant 500 mb
ridge across the U.S. Four Corners region through Saturday
gradually rebuilds southeast into the classic "Canicula"
position, including much of Texas and northeast Mexico, by Sunday
and sprawls across most of Texas Monday through Wednesday, locking
down the heat and really killing off any hint of rain chances.
For the sensible weather...based on persistence with lack of
rainfall nearly everywhere even over the past two days when a
broad upper trough crossed Texas...see no significant upper level
feature to kick off mentionable rain Friday, especially with the
freshening late morning through late afternoon southeast wind.
While can`t rule out a stray shower, especially across the
ranchlands during the afternoon, just not enough to mention now.
Moisture is held to two areas: The typical lifting cumulus field,
and bands of cirrus which have been common in recent days.
Low humidity layer (40 percent or lower) thickens Saturday and
Sunday, expanding from the 700-500 mb layer Saturday to the 850-400
mb layer late Sunday. Entire atmosphere dries out save for a
little very high level moisture and the usual near surface
moisture as the ridge takes over aloft. For the weekend, expect
fewer clouds each day with the usual late morning southeast wind
pickup and some enhanced sea breeze surge by late afternoon/early
evening before subsiding...but still a puff...toward midnight.
As for temperatures, the lack of thick mid/high clouds and
continued thinning moisture will return triple digits back to the
usual suspects along/west of U.S. 281/IH 69C Friday through the
weekend, with 102 at McAllen a pretty good bet by Sunday. With the
lower cloud coverage...thickness near 582-583 out west...and
reaching the peak of our temperatures and mid summer dry
period...recent clear day weather suggest 96 Brownsville/99
Harlingen/103 McAllen Monday through Wednesday with sultry low in
the upper 70s to around 80 just about everywhere.
MARINE: Tonight through Thursday night...Light to moderate southeast flow
and a slight sea to persist through the period. Broad and weak high
pressure to combine with lower pressure in the Bay of Campeche
providing the modest onshore flow. seas to remain steady state under
the weaker flow. A few showers or an isolated thunderstorm is
possible anytime with best chances overnight and early morning.
Friday through Monday...Pretty "classic" Canicular pattern for the
coastal waters. This means persistent but not too strong southeast
flow above the waters, which will mix down better over the warmer
20 to 60 nm waters and help with a modest upwelling case through
the period. Water temperatures will likely "cool" to around 80 or
81 near shore (vs. the upper 70s with the stronger flow early in
July) and help reduce speed especially over the nearshore waters
Sunday through Tuesday. Laguna Madre winds will edge near caution
(15 to 18 knots) each afternoon, otherwise Gulf winds will
initiall begin in the 11 to 15 knot range and slide down to the 8
to 12 knot range as high pressure at all levels takes over.
Seas should average 2 to 3 feet for the entire period; overall, a
good time to fish and boat.
CLIMATE...With the expected above average temperatures to roll
Friday into Sunday, monthly rankings will end up among the top
three hottest (for July) at nearly every location in the Valley.
Comparative years are 1998, 2005, and 2009. A monthly summary will
be issued to describe the rankings and the pattern in early
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