Area Forecast Discussion
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FXUS64 KLUB 260158
AFDLUB

Area Forecast Discussion
National Weather Service Lubbock TX
858 PM CDT MON JUL 25 2016

.UPDATE...
Convective outflow that originated from thunderstorms in the
southern Texas Panhandle this afternoon has now cleared the
southern South Plains. Fairly stable conditions have followed the
outflow as evidence by the relative dearth in shower/storms
activity over a good portion of the CWA this evening. However, we
were still seeing isolated activity where the outflow failed to
push through across the Rolling Plains. In addition, a more robust
cluster of thunderstorms in northeast/east-central New Mexico was
gradually edging eastward/southeastward. It is unclear how far
east this activity will make it, especially on the southern
extent where it encounters the rain-cooled air and stronger
inhibition. Still, given the close proximity and general storm
motion, there appears a decent shot the northwest zones could see
a little more rain through the late evening hours. Elsewhere it is
less certain, but with better tropospheric moisture than recent
days and some elevated instability we can`t rule out more isolated
activity. Given this we have scaled back PoPs to a slight chance
mention over much of the FA while boosting values to the high
chance category across the far northwestern zones. The update
forecast grids and products that reflect the changes have already
been disseminated.

&&

.PREV DISCUSSION... /issued 651 PM CDT MON JUL 25 2016/

UPDATE...
Have adjusted the near-term grids, specifically the temperature,
dewpoint and wind grids, to better account for the convective
outflow that has spread southward through much of the southern
Texas Panhandle and northern and central South Plains. Along with
a brief period of gusty winds this outflow has also knocked
temperatures back into the 70s and 80s, providing a little bit of
relief from the heat. No other adjustments were made to the
ongoing forecast ATTM, though PoPs may need to be revisited later
once it becomes clearer how convection wants to play out.

PREV DISCUSSION... /issued 625 PM CDT MON JUL 25 2016/

AVIATION...
TS dotting the forecast area early this evening, but coverage is
decreasing as sun is getting lower and as cooler outflow air
increases in coverage. A TS at or near any of the terminals in the
first hour or two not out of the question, although appears best
chance at KLBB. Redevelopment of SH/TS possible overnight with
elevated instability possibly being released. Will keep mention
out for now but worth a mention in this space at this time.

PREV DISCUSSION... /issued 257 PM CDT MON JUL 25 2016/

SHORT TERM...
The upper level high pressure dome which has largely suppressed most
sensible weather (other than the heat) has moved far enough west to
enable some changes for us in West Texas.  Model guidance has
struggled with the prospects of thunderstorm development this
afternoon but combining observational inference with some raw data
certain points toward an atmosphere which is much more likely to
convect.  And, this is what has begun to happen early this
afternoon.  Sufficient moisture at H7 and associated instability
above should lead to scattered storms late this afternoon and
evening.  The real question is just how far south things will make
it.  As has been the case with the past few days, any sustaining MCS
will be largely motivated by Corfidi vector motions dependent on
cold pool processes.  This should drive storms slowly southward.
Several models hinted at convective initiation across the western
Texas Panhandle but did poorly with what is appearing to be going on
across much of our area.  Assuming the stronger signal in the
Panhandle is correct, that system should move into the South Plains
by this evening into the overnight hours and have raised pops there
accordingly.  Elsewhere, it`s a waiting game to see just how well
storms can become established in an otherwise weakly sheared and
driven environment.  At the end of the day, just about everywhere
has a shot at seeing some storm development though coverage will
most certainly not be ubiquitous.

LONG TERM...
The western extension of the mid-level ridge remains across the
desert southwest through the week as a deepening trough slowly
displaces the Bermuda High along the eastern seaboard. This will
maintain north to northeasterly flow aloft across west Texas with
sufficient lower and mid level moisture to produce mainly evening
and nighttime thunderstorm chances through at least Thursday.
Medium range models then dry out the atmosphere as the ridge
expands eastward as a shortwave trough digs into the northwest
U.S. coast over the coming weekend. Kept relatively low POPs
through early Wednesday before raising them into chance category
Wednesday evening into Thursday. Uncertainty still exists whether
many storms will initiate Wed afternoon locally along pre-
existing surface boundaries with models forecast soundings still
suggesting a modest mid level subsidence inversion. Expect storms
to increase in coverage late in the evening and overnight as
stronger mid level flow helps convection grow upscale within
theta-e axis shifting south out of the Panhandle. Broad storm
coverage still possible into Thursday with continued weak surface instability
and shortwaves rotating around the high center over the
desert southwest. Temperatures also look to favorably respond to
repositioned ridge with daytime highs closer to average for this
time of year. Don`t expect that to last though as heights increase
again over the weekend and area comes under the influence of lee
side surface trough and threat of downslope winds and lower
humidity.

&&

.LUB Watches/Warnings/Advisories...
None.
&&

$$

07/23



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