Area Forecast Discussion
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FXUS64 KLUB 191713 AAA
AFDLUB

Area Forecast Discussion...UPDATED
National Weather Service Lubbock TX
1213 PM CDT FRI AUG 19 2016

.UPDATE...
Midday water vapor shows the deeper moisture plume skimming our
southeast zones, while the Rolling Plains also had surface
dewpoints in the mid-60s to near 70 degrees. Although weakly
forced, this nearly uncapped and moderately unstable environment
will continue to support the risk of isolated to scattered
convection into the afternoon hours over the southern Rolling
Plains. PWAT values of 1.5+ inches will also provide a risk of
locally heavy rain. Further west the CWA is somewhat drier aloft,
but a pre-frontal surface trough extending southward from the
eastern Texas Panhandle into the South Plains will be a focus for
isolated to scattered convective development by mid-late
afternoon. This activity will be higher-based than further east
and with the deeper mixed boundary layer and drier mid-level air
it could pose a risk of gusty outflow winds. The best shower/storm
chances will actually occur late tonight into early Saturday as a
cold front sweeps southward through the region. Outside of the
frontal forcing, large-scale forcing will be relatively weak, but
at least scattered coverage is expected, with the greater
chances/coverage across the northeastern/eastern zones where
moisture/instability will be highest. The ongoing forecast has a
good handle on all of this and only minor adjustments have been
made ATTM. We have also added a mention of locally heavy rainfall
along with gusty winds to the HWO.

&&

.PREV DISCUSSION... /issued 631 AM CDT FRI AUG 19 2016/

AVIATION...
CIGS at LBB and PVW could briefly brush the MVFR threshold this
morning, but sunrise should return conditions quickly back to VFR.
A slight chance of thunderstorms exists at all terminals this
afternoon, though coverage does not warrant TAF mention attm.

PREV DISCUSSION... /issued 428 AM CDT FRI AUG 19 2016/

SHORT TERM...
A weak shortwave had fired off a round of convection across eastern
NM and the northeastern TX Panhandle early this morning. By 3 AM,
this activity was waning as it was moving off to the northeast. An
outflow boundary from this activity was also pushing to the
southeast into the central South Plains, but it was only
producing a brief wind shift as it moved through.

The presence of the monsoonal moisture plume was noticeable on water
vapor imagery pushing northeast into the Trans-Pecos region. This
will give our southeastern zones another shot at precipitation today
as it combines with a shortwave. Across our northwest zones, an
upper trough combined with a prefrontal surface trough will create
thunderstorm chances starting this afternoon into the evening.
Models have started to come in drier as the front approaches
overnight, so have backed PoPs off from the Likely to Chance
category. It appears we may be headed for a repeat of last weekend`s
rapid FROPA, as the front looks to be pushing through our northern
zones by the end of this forecast period. As the front moves
through, PWATs across the Rolling Plains will be around 1.5 to near
2 inches, so those areas are be favored for the best chance at
rainfall as the front breezes through.

LONG TERM...
Upper low will be situated over Hudson Bay with a rather sharp (for
this time of year) trough extending into the Central Plains Saturday
morning.  As this feature moves eastward, a dirty ridge will become
prevalent across the Central CONUS with another low off the
California coast which will open and drag across the area around the
middle of next week. This California low will phase with another
low sweeping across British Columbia. Thereafter, a series of
disturbances will traverse areas to our north.

Overall, there are many questions regarding precipitation chances
within our CWFA.  The tendency continues for the bulk of the
precipitation to be situated to the south of the area after about
18Z Saturday morning.  With the available moisture and southerly
winds, there still stands a risk of scattered activity Saturday
night through Monday.  All in all guidance appears too wet.  It`s
not to say that rain will not be present, but that activity would be
expected to be a bit more scattered than suggested.  Generally
speaking, this time of year, to get a decent widespread rain out
this way, we need a front to interact with a source of enhanced
moisture such as a decaying tropical system. We will have that for
a while early Saturday but thereafter, not so much. Have therefore
trended POPs down in the extended from what the blends are
advertising. Still, the area will be under the influence of
divergence aloft along along with PWATs of 1-1.5 inches. So,
somewhere will see something just about each day.

&&

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

$$

23/07



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