Area Forecast Discussion
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FXUS64 KLUB 251523 AAA
AFDLUB

Area Forecast Discussion...UPDATED
National Weather Service Lubbock TX
1023 AM CDT SUN SEP 25 2016

.UPDATE...
Cold front is now plowing southward into the northern South Plains
as of 15Z...with gusty northerly winds in its wake. Winds have
occasionally flirted with low-end advisory levels around Friona
and Dimmitt, but think think they will be sustained mostly in the
20 to 30 mph range. Still, will highlight the gusty winds within a
nowcast and adjust accordingly if they do exceed expectation. As
the front is encountering the better moisture it has been
generated scattered showers which should continue to increase in
coverage through late morning and early afternoon. Instability is
rather weak but we could still see a little thunder mix in later
in the day too. We have boosted PoPs along and south of the front
through 18Z...but did begin trimming back PoPs from north to
south during the afternoon and evening hours as it now appears the
drier post-frontal air will tend to win out over the increasing
elevated and weakening lift associated with the upper level storm
system backing away well to our west. Before then, elevated PWATs
could still yield a few locally heavy downpours, though limited
instability and post-frontal dry air advection will tend to keep
amounts in check at any given location as best focus shifts
progressively southward with time. Aside from adjusting the PoPs,
did also change the prevailing weather mention to rain showers with
isolated thunder. Additionally, post-frontal winds were raised a
notch for much of the FA through the afternoon.

&&

.PREV DISCUSSION... /issued 704 AM CDT SUN SEP 25 2016/

AVIATION...
Low stratus ceilings will linger in vicinity of all three
terminals through late morning with deep surface moisture in
place ahead of a cold front currently moving south through the
Texas Panhandle and should be south of KLBB by early afternoon.
KCDS has reported CLR for past couple hours leading up to sunrise
but short term guidance and overall pattern suggest ceilings could
drop quickly into LIFR quickly which has been handled with a tempo
group through late morning. KLBB will likely remain IFR to LIFR
until the front approached with KPVW in mostly IFR/MVFR ahead of
the front. Behind the front winds will be gusty out of the
northeast this afternoon into the evening hours.

PREV DISCUSSION... /issued 529 AM CDT SUN SEP 25 2016/

SHORT TERM...
Light rain currently embedded within gravity waves over Lamb County
seen on local radar as of 430am will be short lived as a cold
front continues to slowly move south out of the Texas Panhandle
into the South Plains. The cold front is struggling to overtake
the very moist surface layer situated primarily east of the I27
corridor where dewpoints remain in the low 60s up into southern
Kansas. While across the southwest Texas Panhandle dew points have
dropped into the mid 30s near Bootleg.

Given the cooler and drier air on the eastern half of the cold front
is struggling to push south, 00z synoptic model run initialization
is less than ideal. HRRR has been trying to catch up and output
seems to be indicating a less dynamic passage east of the I27
corridor which is indicated in the observations. Current water vapor
imagery shows lift associated with the trough pushing through the
Baja of California moving north toward the Guadalupe Mountains but
that lift appears to shift farther east by later this afternoon and
may be enough to destabilize the mid levels over the Rolling Plains.
But farther west into the South Plains any overriding will be weak
or nullified by a weak shear axis from the Pecos area north toward
Lubbock which may leave us drier than expected. Regardless the
precip gradient will be sharp along our southern zones as we go
through the day.

Highs will be in the upper 60s on the Caprock to low 70s in the
Rolling Plains as cooler air moves in eventually behind the cold
front. Rain will linger across our southern counties later tonight
as lift associated with the retrograding low over Baja California
slowly pulls activity to the west and low temps bottom out in the
50s for most of us Monday morning, and into the 40s in our northwest
zones.

LONG TERM...
By Monday morning, we will be pinched between a storm system
across the western Great Lakes and another over Baja California
Sur. Guidance has shifted the low just about 60 miles further west
of the Gulf of California as opposed to the previous run (and
closest to that indicated to the ECM two days ago.) Baja Low
should drift into southern California by late Wednesday before
getting swept up in the westerly flow. All the while, ridging
builds into the Central Plains before flattening toward next
weekend when SWRLY flow returns as another system approaches
Vancouver Island.

Guidance suggests that most, if not all, significant precipitation
should be south of the area by 12Z Monday with mildly breezy NERLY
flow at the surface.  Some showers, however, remain possible
during the day mainly across the southern half. All in all,
guidance tends to over-estimate the residuals, and will taper POPs
downward. The NAM tries to hold on to some POPs in our SW late
Monday into Tuesday though the signal and synoptic setup make
confidence in this scenario quite weak. In fact, given the
available hints in deterministic guidance, it will likely remain
dry for the remainder of the extended.

&&

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

$$

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