Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 240851

251 AM CST Wed Dec 24 2014

.SHORT TERM...(Today through Friday night)
Issued at 233 AM CST WED DEC 24 2014

Low pressure will lift across the TN valley and the Commonwealth
today. As it does, pcpn will expand, and shift eastward as the Low
tracks eastward into Ohio, moving toward the Great Lakes.

The blayer temps look to keep nearly all pcpn in the liquid form
thru the day. The gfs soundings show even the north is probably
all liquid, but a chance of snow on the system`s backside will be
included in the forecast. However, by the time the column temps
fall enough to support snow, the -10 to -20 C layer has dried and
is working down the column. This should keep snow amounts, even in
our northern tier, less than a half inch. This is in good line
with WPC 1" line, which is north of Bloomington Indiana, and in
collab with neighboring WFO`s.

After a brief reprieve Christmas day, warm/moist advection brings
a return chance of showers Friday night, with temps in the 40s.

.LONG TERM...(Saturday through Tuesday)
Issued at 233 AM CST WED DEC 24 2014

An active southwest flow aloft will keep precipitation chances in
the forecast for almost the entire long term period. A series of 500
mb shortwaves will eject northeast across the Mississippi Valley,
bringing periods of rain and possibly some snow. By Tuesday, a major
pattern change appears likely as the 500 mb flow turns more
westerly. This should allow an arctic air mass to penetrate
southeast toward the Lower Ohio Valley and southeast Missouri on

As far as the daily details...
On Saturday and Saturday night, a cold front will move east across
the Lower Ohio Valley. The models have trended slower with the
movement of this front. The slower frontal timing means pops will be
higher and temps will be a little warmer than previously forecast.
Precipitation type will be kept as all liquid through Sunday in most
of the forecast area. Will maintain a mention of a rain/snow mix in
parts of southern Illinois and southeast Missouri on Sunday.

On Sunday night and Monday, a 500 mb shortwave will cross the Lower
Mississippi and Lower Ohio Valleys. Precipitation should diminish
from southwest to northeast with the passage of the shortwave.
Colder air will slowly filter into the region, which could result in
a changeover to snow Sunday night in some areas, mainly northwest of
the Ohio River. There is still a lot of model variability at this
point, but the majority of guidance keeps it mainly rain.

On Tuesday, there is a strong model consensus that the leading edge
of arctic air will either be approaching or overspreading the Lower
Ohio Valley and southeast Missouri. The ecmwf is a little faster
than the gfs with the advance of this arctic air. Some precip cannot
be ruled out along the front, so will carry slight chance pops in
some areas Tuesday.


Issued at 233 AM CST WED DEC 24 2014

MVFR cigs/vsbys will be the rule thru the first half of the
terminal forecast, though IFR cigs may be flirted with at times,
particularly in pcpn. The latter half should see generally
improving conditions, but MVFR cigs may be maintained,
particularly east (KEVV/KOWB).



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