Area Forecast Discussion
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FXUS64 KLUB 242337
AFDLUB

Area Forecast Discussion
National Weather Service Lubbock TX
637 PM CDT WED AUG 24 2016

.AVIATION...
Scattered t-storms continue to develop and move north across the
Rolling Plains with activity further west struggle in more stable
air and away from low level forcing associated with surface
trough. Expect KCDS to have best shot of being impacted by storms
prior to 06Z so included TEMPO group there. Some short term
models indicate more development after midnight which could impact
western terminals also but not enough confidence at this time to
mention. Will likely need to consider extending thunderstorms at
KCDS overnight. Otherwise VFR conditions should persist outside
of convection.

&&

.PREV DISCUSSION... /issued 333 PM CDT WED AUG 24 2016/

SHORT TERM...
We have a few competing factors influencing the rain chances this
evening. In the positive, the upper trough continues to slowly edge
toward the area, and is providing some divergence and ascent within
an upper-level jet of 50 to 60 kts running from Far West Texas into
northwest Oklahoma. Roughly co-located with this jet is a deep sub-
tropical moisture plume with precipitable waters around 1 to 1.5
inches from west to east across the forecast area -although this has
thinned out somewhat from yesterday. In the negative, persistent
cloud cover and ongoing shower activity spreading northeast from the
Trans-Pecos has kept temps relatively cool on the Caprock -with
temperatures still only around 70 degrees in the southwest South
Plains at 2 pm per the West Texas Mesonet. Instability is thus
reduced from yesterday and has inhibited development so far. There
is a a differential heating boundary developing along the eastern
fringe of the the thicker cloud cover running from Lynn County N-NE
into Childress County. And much of the short-term guidance suggests
that this will be a preferred area for development through the
afternoon and evening. The threat of strong thunderstorms and heavy
rain will also be reduced this evening, however with the boundary
running parallel to the mean flow there is some potential for
training activity and locally heavier rainfall totals despite the
lowered instability. A chance of rain showers and a few
thunderstorms will continue overnight, although the bulk of the
activity may shift to the north closer to the alignment of the low-
level jet and a cold front moving south through the panhandles. For
Thursday, the front is expected to make it into the far southwest
Texas Panhandle in the morning before stalling out - of course it
could end up a little north or south than projections. The upper
trough will be moving over the southern high plains, and we
anticipate thunderstorm development in the afternoon in the vicinity
of the front and surface trough extending southward from the front
near the state line. Greater heating and instability will likely
result in some stronger storms. Deep-layer shear will likely keep
the severe potential low, but locally heavy rain and minor flooding
may be the biggest threat given the potential focus of the front,
moderately rich deep-layer moisture, and slow storm motion.

LONG TERM...
Recent and narrow axis of mid-level moisture with episodic storms
will slowly diminish in girth by late Thursday all the while
shifting farther north into the Panhandles. This process is in
response to a departing trough Thursday night and a subsequent
development of reduced meridional flow. Satellite derived PWAT
imagery also indicates a wedge of lower values over the Edwards
Plateau that will expand north atop the South Plains by Friday.
Until then, Thursday night still favors the highest PoPs of 40-50%
in our NW zones near a residual front and surface trough with some
background ascent courtesy of the aforementioned upper trough.

By the weekend, the western periphery of zonal ridging will expand
toward West TX and serve to re-introduce higher PWATs of generally
1 to 1.5 inches. However, modest height rises during this time
could very well suppress storm coverage more than the bullish
Superblend indicates. As a modest trough departs the southern
Rockies on Sun, the weak ridge should falter and yield improved
precip chances. Newest models and ensembles show growing
consensus towards a subtropical high redeveloping somewhere over
the southern Great Plains toward Tue/Wed. This would effectively
quell the recent unsettled pattern and serve to boost high temps.

&&

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

$$

33/93/24


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