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000
FXUS64 KLUB 190229 AAA
AFDLUB

Area Forecast Discussion...UPDATED
National Weather Service Lubbock TX
929 PM CDT Mon Sep 18 2017

.UPDATE...
Minor update to extend the isolated thunderstorm mention to
encompass the far eastern zones through the remainder of the
evening hours. Current small but occasionally fairly robust
convective cores have continued to persist and even expand in
coverage this evening. They may continue right into the eastern
Rolling Plains. Given the trends, have expanded the mentionable
PoPs eastward this evening. More recent iterations of the RAP,
HRRR and TTU-WRF also indicate potential isolated activity
redeveloping further west over the South Plains tonight. Given
modest moistening seen upstream in the water vapor imagery, decent
residual elevated instability that will be in place and a
developing southerly LLJ, additional (albeit likely isolated at
best) convection appears possible late tonight into the early
morning hours Tuesday. Given this we have also added a minimal
thunder mention for much of the CWA in the 06-12Z time-frame. No
other significant adjustments were made to the forecast at this
time.

&&

.PREV DISCUSSION... /issued 632 PM CDT Mon Sep 18 2017/

AVIATION...
VFR conditions are expected through Tuesday. Isolated showers with
a bit thunder should remain south of the terminals this evening.
Without the cool post-convective air mass ala last night,
restrictions to visibility and/or ceilings are unlikely.

PREV DISCUSSION... /issued 320 PM CDT Mon Sep 18 2017/

DISCUSSION...
Two weak areas of surface convergence, one along the northern
borders of Garza to Stonewall counties and the other across
southeastern Briscoe county, and a dryline currently in eastern NM
will be the main areas of focus for potential convective
development later this afternoon and evening. The timing of
initiation should line up with a jet maxima pushing northeastward
out of Chihuahua. Currently the FA is located along the exit
region of the jet maxima which is aiding in some subsidence. Storm
chances should decrease after sunset as the jet pushes east of the
FA. Some storms could become severe and produce damaging winds up
to 70 mph and hail up to one inch. Rain chances will be low
tomorrow into Thursday and Friday as flow remains mostly zonal
aloft.

By late weak an upper low will dig southward across the western
CONUS placing the region back under southwesterly flow aloft. A
lee trough will allow surface winds to be out of the southeast
transporting Gulf moisture into the FA ahead of the approaching
upper low. Rain chances will increase from the west as the low
moves slowly towards the FA by Friday into Saturday. The 12z model
runs have slowed down the eastward progression of the upper low
which would delay the timing of lift moving into the region.
Previously models were showing decent lift pushing into the FA by
late Friday into Saturday but are now holding off until late
Saturday/early Sunday. Given the slower model guidance pops will
continue to be kept below the likely category with higher chances
favoring our northwestern zones. Chances will increase as a front
pushes southward into West Texas early next week. As ample
moisture will be in place and the low will be slow moving heavy
rain could very well be possible, but it is still too early to
tell. Temps, however, should be cooler and more fall like as the
front moves through and cloud cover remains.

&&

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

$$

23/07