Area Forecast Discussion
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FXUS64 KLUB 200211
AFDLUB

Area Forecast Discussion
National Weather Service Lubbock TX
911 PM CDT Thu Sep 19 2019

.UPDATE...
MCS moving across the eastern Panhandle has led to an adjustment
to raise precip chances across the northeastern counties.
Elsewhere, could see some additional convection try to form along
and behind the outflow boundary. Otherwise, models have backed off
chances for additional precipitation for the remainder of the
night. Still, elevated instability and lingering mid level
moisture will lead to prudence of keeping 20-30 percent PoPs in
the forecast for the overnight hours.

&&

.PREV DISCUSSION... /issued 627 PM CDT Thu Sep 19 2019/

AVIATION...
TS will primarily stay to the north and northwest of the terminals
this evening, but close enough of a threat at KLBB and KPVW to
keep a mention going for the first two to three hours of the
forecast. Some indication that there will be low clouds with MVFR
ceilings Friday morning, but confidence is low right now given
lack of consensus. Will maintain VFR forecast conditions at this
time.

PREV DISCUSSION... /issued 315 PM CDT Thu Sep 19 2019/

DISCUSSION...
Thunderstorm chances over the next few days, including the risk of a
couple strong to severe storms capable of producing locally heavy
rainfall, highlight this afternoon`s forecast package.

A broad western trough will continue to advance steadily eastward
the next several days, with a portion of the trough lifting out
across the central/northern High Plains Saturday, and the remaining
piece following on Sunday. In advance of the troughiness,
unsettled southwesterly flow aloft will persist over West Texas,
along with a gradual increase in deep layer shear. In addition,
moisture levels will rise, helping support moderate instability at
times. The combination of the increased wind shear and
instability will support greater coverage and intensity of
storms...at least around peak heating this afternoon, tomorrow and
Saturday (and perhaps Sunday). Not to be forgotten, several
embedded weak disturbances, including one this afternoon/evening
and perhaps another grazing the region late tonight (well after
midnight) will aid in thunderstorm development.

In the short term, we have already seen the greatest coverage of
storms form near a surface trough stretching from the western
Texas Panhandle into east-central New Mexico, with more isolated
activity forming along a couple of residual boundaries from the
South Plains into the Permian Basin. This activity will move
eastward/northeastward through the evening hours. A few of these
storms could become strong to marginal severe given the modest
instability and marginal wind shear in place, before generally
fading mid-late evening. However, we could see another round of
convection attempt to move into the western counties toward Friday
morning, associated with the next upper level disturbance.

Beyond that, a good fetch of mid-upper level moisture from the
tropical activity in the eastern Pacific will continue to stream
over the region through much of the weekend. This
moisture/instability, combined with the unsettled southwest flow
aloft, will keep occasional storm chances (some which could be
strong/severe) in the forecast. However, the details on exactly how
thing play out will depend on previous day`s convection and timing
of subtle upper level disturbances, both which will have to be
resolved in the shorter term. Until then, we have maintained solid
rain/storm chances through the weekend. By late weekend, we may see
a brief bout of shortwave ridging, but a weak cold front may also
sag through the Panhandle, and perhaps into the South Plains,
which could provide a focus for additional storm chances.

There may be a bit of a brief lull in precipitation chances early
Monday, associated with the progressive shortwave ridging. However,
eyes will then be fixed on how the next storm system, likely a
closed low, evolves across the west. NWP continue to struggle on
if/where the low will become cutoff, varying from Arizona to
somewhere closer by. Obviously, this will have a big influence on
weather impacts locally. For now, we have maintained 20-30% PoPs at
the end of the forecast.

&&

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

$$

07


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