Area Forecast Discussion
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FXUS64 KLUB 220547

Area Forecast Discussion
National Weather Service Lubbock TX
1247 AM CDT Fri Sep 22 2017

Stout southerly LLJ sampled at 40-50 knots by the TTU SODARs
could yield periods of LLWS at the terminals where surface winds
drop off early this morning. The LLWS will diminish toward dawn
with breezy southerly surface winds following through much of the
day. Before then, the LLJ will carry improving levels of moisture
this way. We could see MVFR cigs make a run at KLBB (and
potentially the other sites) near or shortly after daybreak,
though the majority of the guidance suggests the sub-VFR clouds
should come up just short of the terminals before scattering out.
Given this have maintain VFR in the TAFs, though a period of MVFR
cigs is not out of the realm of possibility. Beyond that, convection
is expected to fire this afternoon and evening, though it should
remain well west of the terminals near the TX/NM line.


.PREV DISCUSSION... /issued 319 PM CDT Thu Sep 21 2017/

Thunderstorms will be possible again this afternoon mainly across
the Rolling Plains where better boundary layer moisture resides
and temperatures have climbed into the mid to upper 90s. Elevated
cloud bases will result mainly in a damaging wind threat from
downbursts but a few hailstones cannot be ruled out either. After
tonight, we will start to transition the rain chances back to the
west and spreading to the east through the weekend as a strong low
moves across the western part of the U.S. and opens into a
longwave trough that will remain across the Intermountain West.

Ahead of this trough, a good fetch of moisture both from the Gulf
of Mexico at the surface and from the Pacific aloft will start to
spread over the region. Initially, rain chances will be driven by
weak disturbances moving over the area in southwesterly flow
aloft through the weekend. By the first part of next week, a cold
front will start to push southward but the models differ on when
it will move across the area. The ECMWF is the fastest with
arrival in our forecast area late Monday into early Tuesday while
the GFS hold off bringing it into the northwestern half of the
area Tuesday night. Then, the GFS never really fully pushes the
front through until late Wednesday into early Thursday morning.
The front will serve to focus rain chances even more with the best
chances with the frontal passage and across the Rolling Plains.

With the trough axis remaining west of the area through
potentially Thursday to Friday of next week, we should have a
pretty good period of rain chances along with below normal
temperatures through much of the extended forecast. Moisture
levels above normal will result in the potential for locally heavy
rainfall early next week but the heaviest amounts will be pretty
localized. The threat for severe weather will exist through the
upcoming weekend before lapse rates aloft start to lessen lowering
the potential for severe weather through next week. Do believe
that we should start to have drier air push in behind the front
for the latter part of next week so rain chances will start to
drop off Wednesday night and gradually drop to below mention by
Thursday night into Friday morning.





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