Area Forecast Discussion
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FXUS64 KLUB 221127
AFDLUB

Area Forecast Discussion
National Weather Service Lubbock TX
527 AM CST Thu Feb 22 2018

.AVIATION...
IFR conditions to persist through the morning with improvement
expected to MVFR and then VFR during the afternoon. -FZDZ coming
to an end, but some patches will still be possible.

&&

.PREV DISCUSSION... /issued 351 AM CST Thu Feb 22 2018/

DISCUSSION...
Chilly and moist surface ridge continued to plague the region
this morning with frequent bouts of freezing drizzle, particularly
on the Caprock where we`ve seen regional webcams and vehicles
glaze over with ease. Traffic slowdowns are becoming more frequent
(particularly on area overpasses) per Google traffic data, so with
no definitive break foreseen with freezing drizzle until later
this morning, have issued a Winter Weather Advisory for the
entire forecast area until noon. In general, a thin glaze to 0.01"
of ice can be expected. By later this morning, much deeper and
drier SW flow will overspread the region in association with an
upper trough lifting across the Colorado Plateau. This will scour
out stratus and bring an end to residual precip while finally
allowing temperatures to climb into the 40s and lower 50s. Still,
opted to keep highs on the cooler end of MOS guidance given
southerly winds sourcing chilly trajectories from the departing
surface ridge.

In advance of another upper trough tracking even closer to the
region by late Friday, low level moisture should return to most of
the area on backing surface winds. NAM looks the most reasonable
with its depiction of widespread stratus Friday night and some
drizzle or light rain (temps are expected to remain above
freezing this time around). Forcing for ascent does not appear too
shabby as we`ll have a Pacific front and about 60 meters of mid-
level height falls available, but given the largely veered flow
above the shallow saturation, have kept measurable rain chances
off the Caprock.

Westerly winds should amplify considerably on Saturday as the base
of the aforementioned trough reaches the South Plains by peak
heating. A stout wind max of nearly 60 knots at 700 mb fits the
bill for windy and dusty conditions over much of the region, but
likely falling within wind advisory criteria. Fire-wise, models
still look too moist behind the Pacific front on Saturday. As
history has shown us many times before, this moisture is often
quick to mix out on strong downsloping winds while also garnering
much warmer high temps. Nudged the forecast in this direction and
we will probably need a Fire Weather Watch in later forecasts.

For Sunday and Monday, a semi-zonal flow regime with insignificant
upper impulses looks to return us to a largely uneventful weather
pattern. Toward midweek, backing of winds aloft to a SW direction
should encourage some low level moisture return to at least our
eastern zones ahead of a mobile trough upstream. Considering the
GFS and ECMWF still depict a healthy subtropical jet in our
vicinity, deeper moisture could come into play at some point
resulting in decent PoPs as the upper trough arrives Tue or Wed.
Unless this trough slows or deepens considerably and can turn our
flow more meridional, am inclined to keep rain chances east of
the 100th meridian for this pattern.

&&

.LUB WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until noon CST today for TXZ021>044.

&&

$$

93/07


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