Area Forecast Discussion
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FXUS64 KLUB 080535

Area Forecast Discussion
National Weather Service Lubbock TX
1135 PM CST Wed Dec 7 2016

MVFR to low VFR cigs have been common through the evening. Expect
this to continue through Thursday morning, with KLBB and KPVW
having the best chance of experiencing prolonged periods of sub-
VFR conditions. VFR should eventually become more common at all of
the terminals by late morning or early afternoon. Before then, a
few flurries (perhaps even light freezing drizzle) could fall,
though no impacts are expected. Breezy northerly/northeasterly
winds overnight will ease through the day before veering easterly
and eventually southerly by late Thursday evening.


.PREV DISCUSSION... /issued 336 PM CST Wed Dec 7 2016/

Winds have shifted to northerly across most of the forecast area as
of 20z. Winds have also started to increase across the southwestern
Panhandle with 15-20 knot winds from Friona to Dimmitt. High
pressure will continue to build in through the evening with surface
winds increasing to near 20 knots from the NE with higher gusts. Low
clouds have cleared across the NW South Plains and SW Panhandle but
stratus will fill back in fairly quickly in post frontal airmass
this evening. Temperatures will steadily fall late today and early
on Thursday. Morning lows Thursday will range from 12 at Friona
to 23 across the southern Rolling Plains near Aspermont. Winds
will subside somewhat after midnight but still remain in the 10-15
mph range by mid morning Thursday. Wind chills around sunrise
ranging from near zero NW to lower teens SE.

Airmass will saturate through a deeper layer toward midnight with
very light precipitation becoming more likely in the early morning
hours Thursday with weak lift and upslope flow. Given temp profile
of near -10C temps in lower to middle part of saturated layer...
expect a few snow flurries with also the chance of some very light
freezing drizzle. Measurable pops are low and we are not
anticipating much in the way of impacts. Likely to see some light
precipitation through 18Z (noon) Thursday with subsidence and a
moist layer becoming more shallow and drier thereafter as high
builds farther southward. Models indicating higher moisture and
light precipitation more likely across the southwestern South Plains
from Lubbock and points west and south especially toward noon
Thursday. Highs tomorrow struggling to reach the freezing mark on
the Caprock...and a few degrees warmer in the SE Panhandle and
Rolling Plains in the mid 30s. James

Tomorrow`s stubborn low clouds should undergo steady erosion and
thinning by Thursday night as cold surface ridging departs the
region. Soundings still indicate some potential for weak, but
moist, isentropic ascent which could sustain some thin clouds
through Friday. Despite breezy downslope winds and more sunshine,
high temps will struggle to break out of the 40s thanks to a lingering
850mb thermal trough and chilly/recycled southerly trajectories.
Thicknesses will amplify considerably on Saturday under deeper
westerly flow, with very breezy surface winds ahead of lee
troughing. Confidence is increasing that this warming will end
abruptly by Sat night as a fast-moving trough in WNW flow drags
down the first in a series of progressively colder and more
significant cold fronts/reinforcements for next week. Opted to
lower max temps a couple degrees closer to blended guidance, but
if the cold GFS temps gain some momentum then our values will need
more aggressive reductions. This cold airmass could easily linger
through Monday, particularly off the Caprock, until SW winds gain
momentum by early Tue ahead of a stout Arctic front.

Global models and GEFS members are in good agreement that the
Polar Vortex will peel off a low through the Canadian Prairies by
Sun. This process will dislodge a significant Arctic airmass with
850mb temps below -30C, likely racing south through the Great
Plains by early in the week. Even with a broad cyclonic NW flow
regime, such bitter airmasses don`t necessarily require meridional
flow to plunge this far south. On that note, the ECMWF`s bullish
depiction seems more plausible than the modified/weaker and
successive cold pushes of the GFS and its vastly milder temps.
Drew into this strategy by lowering highs several degrees from
before for Tue and Wed, but it`s too soon to consider introducing
any of the climatological freezing drizzle that tends to accompany
such strong fronts.




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