Area Forecast Discussion
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FXUS64 KLUB 030420
AFDLUB

Area Forecast Discussion
National Weather Service Lubbock TX
1020 PM CST Fri Dec 2 2016

.UPDATE...
No changes are required at this time. Precipitation chances will
improve later tonight into Saturday while cooling near the surface
and aloft will result in improving chances for snow, sleet, and
even perhaps freezing rain in our northwest corner later tonight
and early Saturday. A Winter Weather Advisory remains valid in
this area through noon Saturday.

An expansive shield of isentropic driven rain was finally letting
go across our area late this evening, with a brief letupunderway.
However strong dynamic jet forcing was on the verge of lifting a
new enhanced precipitation shield northward from the Permian
Basin. So, the real result is hardly any break. Latest solutions
continue to spread abundant precipitation into our area late
tonight through Saturday morning. And the boundary separating
wintry precipitation from liquid has barely nudged from earlier
today. RMcQueen


&&

.PREV DISCUSSION... /issued 549 PM CST Fri Dec 2 2016/

AVIATION...
Poor flying weather is expected for the next 24 hours. IFR
conditions are likely at all TAF sites with possible LIFR at KLBB
and KPVW through the nighttime hours.

PREV DISCUSSION... /issued 346 PM CST Fri Dec 2 2016/

SHORT TERM...
A widespread cold rain event remains on track for the overnight
hours into Saturday. It does still appear it may cool just enough
to support the risk for a wintry mix and generally light
accumulations of snow, sleet and freezing rain across the extreme
southwest Texas Panhandle into the northwest South Plains late
this evening into Saturday morning. A winter weather advisory
remains in effect for Parmer, Castro, Bailey and Lamb Counties
from 9 pm tonight to midday Saturday.

Rain showers, even a few rumbles of thunder, continue to expand
across much of the central and eastern zones this afternoon in
response to increasingly moist and deep isentropic upglide. The
precipitation was falling as a cool rain with 21Z temperatures
mostly from the upper 30s to middle 40s. The isentropic upglide will
continue through the overnight hours, though overall lift and
intensity of precipitation may wane a bit toward 06Z. However,
another shot of lift is expected to pivot this way in the diffluent
flow ahead of the gathering upper low now sinking toward the Gulf of
California. This should renew precipitation coverage and intensity,
spreading from southwest to northeast across the CWA Saturday
morning. After that, lift may again wane meaning a return to lighter
precipitation, including drizzle and possible fog. NWP remains firm
that much of the area will see anywhere from 1/2 inch to over 1 inch
by 00Z Sunday, with the heaviest amounts across the southeastern
zones.

Of additional concern is the prospect for frozen precipitation
across our far northwestern zones late tonight into Saturday
morning. Progged soundings around Friona show a weak warm nose
persisting much/all of the night as surface temperatures edge down
toward or slightly below freezing. This will support a wintry mix of
freezing rain, sleet and snow, with snow most likely during the
heaviest bursts of precipitation when dynamic lift will further cool
the column. It appears this would be most likely Saturday morning
with NWP suggesting a decent band of precipitation traversing the
northwest zones. Within said band a quick 1-3 inches of snow is
possible, though outside the stronger lift, lighter accumulations of
a mixed bag will exist. Unless temperatures fall below what is
anticipated or the heavy banded precipitation persist longer than
expected, would expect overall impacts to be relatively low given
the damp and relatively warm ground.

Regarding temperatures, we will not see much variation as skies
remain cloudy through the short term. Lows tonight will be mostly in
the middle 30s to lower 40s, aside from the far northwest zones
where it should drop into the lower 30s or upper 20s. Highs Saturday
will only make it into the upper 30s to lower/middle 40s.

LONG TERM...
Precipitation should begin to come to an end across the
northwestern zones late Saturday evening as the jet streak that is
in part responsible for the rain/mix event tonight and Saturday
begins to shift to east/northeast away from the region. The closed
low will move southeastward along the Gulf of California Saturday
night then turn inland over the Mexican interior early Sunday and
eventually tracking across southwest Texas Monday. This track will
keep a chance for rain across the southern part of the forecast
area through Sunday night (and a sliver of the southeastern zones
Monday).

Focus then shifts to the potential for cold air moving southward
out of Canada in a set of two waves. The initial wave will come
Tuesday returning temperatures to below normal after temperatures
Monday almost bang on normal. This first wave stalls out in or
just south of the forecast area returning a bit to the north
Tuesday night before making a return at some point Wednesday with
markedly colder temperatures associated with this second frontal
passage. The 12z model suite has backed off the timing of the
front Wednesday, but that is not always the way to go with these
cold, dense air masses. The supporting upper trough seems to be
playing a significant role here in holding up the cold air. Again,
that may not be the right move. Will moderate Wednesday`s forecast
highs a bit from the previous run but undercut MOS and the model
blend. The cold air will settle in Wednesday night and Thursday
before beginning to moderate Friday. With broad cyclonic flow over
the area coinciding with the cold air snow flurries will not be
out of the question, but measurable precipitation will be hard to
come by without a short wave or jet streak for focus.

&&

.LUB WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until noon CST Saturday for TXZ021-022-
027-028.

&&

$$

05/99



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