Area Forecast Discussion
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825
FXUS64 KLUB 221942
AFDLUB

Area Forecast Discussion
National Weather Service Lubbock TX
242 PM CDT Mon May 22 2017

.DISCUSSION...
Following a temporary bout of active weather later this afternoon
lingering into Tue morning, the remainder of the week promises to
be quiet with hot temperatures building by late week under very
deep and arid westerly flow.

Today and Tonight...Mid-afternoon observations indicated stratus was
eroding aggressively across far eastern NM ahead of discrete storms
from Santa Rosa to Roswell within a Theta-E ridge. A weak surface
trough from near Clovis ENE to Pampa was drifting slowly south, with
some enhanced Cu observed at times along the western extent of this
boundary. Farther north, a cold front was accelerating south across
the NW Panhandle and northeast NM ahead of a shortwave trough
tracking ESE. Latest thinking is that orographic storms in NM will
track SE and maintain severe potential as they remain embedded
within MLCAPE around 1000 J/kg. Despite anemic lower tropospheric
flow, deep layer westerly shear of 40-50 knots should still be
supportive of decent storm relative inflow to maintain supercell
structures, until storms trend more linear early this evening as the
aforementioned surface trough drops south and veers low level winds
more northerly. Current blue box may need to be expanded into the
remainder of our South Plains` counties if storm modes grow upscale
as forecast. Otherwise, the brunt of surface based convection should
depart the region before midnight ahead of deepening northerly flow
behind the upper trough and cold front.

Tuesday and Tuesday night...On the heels of tonight`s cold front, a
more robust cold front (presently in northeast CO) should reach the
CWA before sunrise ahead of 20-30 mph northerly winds. Prospects for
additional precip with this front are looking less than originally
indicated, but at least a narrow axis of moist Fn ascent could wring
out a few showers before mean layer subsidence deepens from N-S
through the morning. Steady cold advection through the day will
only add momentum for a very cool night as a surface high
overspreads the region with light winds and mostly clear skies.

Wednesday through Sunday...Beginning Wednesday, progressive upper
ridging will help restore more seasonable thicknesses to the TX
South Plains, although low level return flow will be devoid of any
appreciable moistening following Tuesday`s front crashing into the
Gulf. Behind the upper ridge, deep westerly flow will advect an
unseasonably warm dome of Desert air eastward on Thursday and
lingering through Saturday. Gulf moisture will return with time, but
under such deep westerly flow this will favor the dryline east of
our domain almost every day, which only increases the likelihood of
widespread heat on breezy and arid downslope winds. Superblend
appears much too generous with post-dryline dewpoints Thu-Sat, so
have skewed this lower more in tune with the drier GFS and ECMWF.
Cyclonic upper flow by Sat night on the fringes of a larger Northern
Plains` trough should at the very least deliver a welcome cooldown
for Sunday, with perhaps some rain chances as Gulf moisture curls
westward behind the front in moist upslope flow.

&&

.LUB WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

93



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