#404 Postby Rgv20 » Sat Aug 06, 2016 4:47 pm
NWS Brownsville afternoon discussion....Looks like by the end of Next Week and the Weekend will be crazy hot! 12zGFS Ensemble Means has a high of 104 for McAllen next Saturday...Crazy for being an Ensemble Mean!! Wonder if my area can hit 110+ sometime next week since late June its been 103+ and the highest temperature was 107 a couple of times.
.LONG TERM (Monday through Saturday): If the swelter wasn`t
already enough through what remains a Top 2-3 (for most) hottest
past 40 days dating back to the end of June, the latter part of
next week brings the heat to a further crescendo with perhaps the
hottest temperatures of the summer.
Before then, the trends continue to lean away from rainfall, with
only a slim possibility remaining for Wednesday which even then
may become generous if moisture and forcing trends continue.
Through the entire period, 500 mb ridge remains parked across
Texas, with the peak of the summer heat arriving by late week fed
by upper trough riding through the central/northern Plains and
bringing surface pressure falls from the Plains through the lee of
the Sierra Madre. This pattern squeezes compression/subsidence
aloft and feeds the "Valley Wind Machine" further, leading to even
more heat than we`ve already seen.
For the sensible weather, Monday and Tuesday see solid deep layer
drying enough to pull column RH values above the obligatory cu
deck below 40 percent, with even lower values above 500 mb, as a
piece of ridge breaks off and centers over Deep S. Texas. Can`t
completely rule out a stray sea breeze shower in Cameron/Willacy
but not enough to mention. With ample sunshine have raised
temperatures a degree to match similar trends this summer.
For Wednesday, the GFS continues to show an embedded north-moving
short wave inside the uppper ridge, which builds just enough
moisture (60 percent or so) between 850 and 500 mb above the cu
deck to allow for the *potential* for some seeding of the sea
breeze. By late afternoon, however, this moisture layer shifts
west which argues for the typical sea breeze "jump" and pulls any
mentionable rain inland. The ECMWF is a tad more bearish...not
showing any notable short wave energy and no big moisture flux out
of its ordinary typically higher values. For now, just have
mention near the coast in the morning, a thin stripe inland
(not including the Upper Valley) during the afternoon, and
temperatures just a degree lower overall than on Tuesday.
By Thursday, that moisture plume is gone and the influence of the
central/northern Plains trough (approaching) begins to be felt
with an increase in southerly flow. Some layered humidity remains
but plenty of drying off the cu deck so removed mentionable rain
chances and kept the 98/101/104 (Brownsville/Harlingen/McAllen)
idea alive. May need to keep an eye on apparent temperatures as
dewpoints should remain just high enough to possibly require Heat
Advisory (111 or higher for two hours by day).
Deeper dry air returns Friday and Saturday but with plenty of
afternoon breezes and impressively warm thermal parameters,
including 25C at 850 mb and 1000-500 thickness reaching 585 dm in
the mid Valley. Went with a 105 McAllen on Friday and back to 104
on Saturday, with lower dewpoints (mid to upper 60s) keeping heat
index values right on the edge but likely between 105 and 110.
&&
.MARINE: ore moderate seas...2 to 4 feet with some occasional 5
foot waves...will continue through this evening and on early
Sunday as lingering swells move through the coastal waters. A
slight tightening of the surface pressure gradient my enhance some
wind waves...but do expect this to lessen by Sunday. In
fact...winds and seas will generally relax heading into the new
work week.
Monday through Thursday Night: Light to moderate winds (higher by
day in the bay and by night in the Gulf) and slight to moderate
seas, mainly 2 to 3 feet, through mid week. By Thursday and
Thursday night, the southerly gradient picks up which will help
boost Gulf winds and night and Laguna winds by day into caution
levels, but the building southerly flow will also bring an
upwelling component that will begin cooling the nearshore waters
and is likely to cut down daytime winds, particularly beyond the
forecast period. All in all, a decent time to boat and fish
though wind wave (chop) will become an issue for Bay and Gulf
especially by Thursday.
&&
.CLIMATE...As mentioned on the briefing
(weather.gov/rgv/?n=briefing) this morning, the next two weeks
appear to "double down" on the persistent heat. With the
increasing southerly flow to close out next week, potential for
degrading drought conditions to moderate beyond U.S. 281 is not
out of the question by mid month. Breezy dry conditions could also
improve the potential for rapid spread of any wildfire starts;
just something to be aware of and practice safety for as next week
progresses.
Relatively high probabilty of above average temperature and below
average rainfall continues beyond the prohibitive end of the
"Canicula" period (August 11), and the 3 to 4 week outlook
suggests the same to conclude August. This could have significant
impact on further drought conditions and wildfire spread
potential, and would diverge from the long term climatological
average which is a steady rise in rainfall frequency with time.
Stay tuned. And stay cool!
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August is traditionally our hottest month. I guess I can dream.
