High Wind in Texas, December 13, 2018

Area Forecast Discussion
National Weather Service Lubbock TX
1050 PM CST Wed Dec 12 2018

.UPDATE...
Have trimmed a couple hours off the beginning of the High Wind
Warning. Cold front still in CO/KS. Expectation of arrival into
the forecast area around 08Z/09Z.

&&

.AVIATION...
Cold front moving quickly southward through souteastern Colorado
and western Kansas will be at the TAF sites by 09Z/10Z. Very
strong winds in excess of 30 kts with the possibility of gusts
greater than 50 kts. Still some light snow potential at KLBB and
maybe KPVW. Forecast on track with little change from 00Z TAF
cycle.

&&

.PREV DISCUSSION... /issued 323 PM CST Wed Dec 12 2018/

DISCUSSION...
Focus for this go at the forecast remains on the increasing
potential for a high wind event across all of the South Plains,
Rolling Plains, and far southern Texas Panhandle tomorrow. A
deepening closed low over Colorado tonight will drop south across
the forecast area tomorrow morning. We have a climatological
study for high wind events across the region and even though this
was developed back in the NGM model era, it is still relevant in
today's world of higher resolution models. Looking at all models
we have available and plugging the parameters needed (generally
based on height/pressure gradient, vorticity advection, mixing
potential, and stability indices), every model is pointing at
sustained speeds above 40 mph for the forecast area with the
potential for gusts approaching 60 mph. Continued indications in
the models with good run-to-run consistency indicate that we will
likely hit high wind warning criteria and have opted to upgrade
the watch to a warning for Thursday. The high wind warning will
run from Midnight Thursday through 6 pm Thursday evening as the
gradients starts to relax as the low moves further east away from
the area.

The second main issue will be the potential for precipitation with
the arrival of the low across the area. Unfortunately where the
models have good consistency in the wind speed forecast, there is
a lack of such for precipitation coverage and type. Overall the
models have dried out a bit and reduced the coverage of
precipitation with the low as it moves across the area. There will
be an area across the South Plains that develops early in the
morning with the arrival of the front and with the main lift
associated with the core of the low. A second area of
precipitation will then develop around the northern edge of the
low in a weak TROWAL/deformation zone that tries to develop
through the afternoon across the Rolling Plains. Precipitation
will initially start off as a rain/snow mix but the arrival of the
main low will quickly shift the entire atmospheric column below
freezing so a quick transition to snow after sunrise is expected
across the Caprock. With a thicker boundary layer depth over the
Rolling Plains, precipitation may remain more of a mix until later
in the afternoon. Strong north wind through the day combined with
the snow will result in some areas of low visibility, perhaps
below one mile at times according to some of the higher-resolution
models, due to blowing snow. The flip side to this is that
accumulations are not expected to be more than a few tenths of an
inch but strong winds will result in southward-facing drifts
behind any obstacles to the wind that may result in localized
accumulations. There could also be some dust mixed in with the
snow but we are unsure how much dust will be able to become lofted
with the ground still moist across areas where the heavy snow
fell Saturday. May have to add blowing dust to the grids tomorrow
but opted to leave out for now so that the forecast didn't get too
muddled with a plethora of precipitation types.

This system will shift east by Friday afternoon as the last lobe
of vorticity pushes east of the area. Quiet weather will ensue
through the upcoming weekend as shortwave ridging moves across
the region. After that, another trough may start to impact the
area on Monday but with the focus on the high wind event for
tomorrow, only adjustment was to remove any PoPs mentioned on days
6-8 in the forecast until the models give us a better idea of how
the system will develop.

Jordan

&&

.LUB WATCHES/WARNINGS/ADVISORIES...
High Wind Warning from 2 AM to 6 PM CST Thursday for TXZ021>044.

&&

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