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000
FXUS63 KPAH 231714
AFDPAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
1115 AM CST Fri Jan 23 2015

.UPDATE...
Updated the aviation discussion for the 18Z TAF issuance.

&&

.SHORT TERM...(Today through Sunday night)
Issued at 329 AM CST FRI JAN 23 2015

Forecast confidence average to below average today into this
evening. Let me start out by saying that models are not in good
agreement on the finer details of the atmospheric thermal profile,
which makes all the difference where precipitation type is
concerned. They are however are in better agreement as to the amount
of QPF expected.

A low pressure system will track from near the panhandle of Florida
to the outer banks of North Carolina between 12Z (6 AM CST) this
morning and 06Z (midnight CST) tonight. As the storm passes by to
our south, an overrunning precipitation scenario will unfold that
will primarily affect the southeast half of our CWA starting around
12Z. If temperatures were a bit warmer, this forecast would be
fairly straight-forward, but with readings starting out around the
freezing mark, and per 1000-850 MB critical thicknesses and model
soundings, precipitation should start out as snow, but with QPF
amounts being so light, expect little to no snow accumulation in the
12-15Z time frame.

As the lower levels of the atmosphere begin to warm a few degrees
starting around 15Z precipitation should become a rain/snow mix. Due
to the lack of continuity between models where precipitation type is
concerned, decided to continue with a rain/snow mix through 23Z
(5 PM CST) with little to no snow accumulation expected.

Over our southeast counties around 18Z the GFS shows an area of mid
level omega coincident with 2-D frontogenesis and saturated geo
potential vorticity. The alignment of these features typically
indicates the potential for precipitation banding, but in this case
the QPF amounts are so low, I don`t see it being a problem.

From 00Z on the atmosphere begins to cool enough to change
precipitation over to all snow. Unfortunately for the snow bunnies
out there, by the time the column begins to cool enough for snow,
the majority of the QPF will have moved off to the east. Therefore
only minor snow accumulations (< 1") are expected generally south
and east of a line from Central City to Murray Kentucky with the
highest probability over the far southern Pennyrile area.

Beyond that high pressure should keep the region dry through
Saturday night. On Sunday an H5 trough pushes a clipper system
rapidly across the region which may produce rain chances over all
but the far western sections of our CWA. Precipitation should be all
rain on Sunday but Sunday night as the colder air filters in behind
the system, rain may mix with or eventually change to snow before
ending. Little to no snow accumulation expected at this time.

.LONG TERM...(Monday through Thursday)
Issued at 329 AM CST FRI JAN 23 2015

Above average confidence in the extended forecast.

A good deal of the confidence is derived from the fact the models
have been fairly stable with very few fluctuations in the extended.
There are still a couple days that will have to be closely monitored
for possible changes as some weak systems move through. Monday will
likely be a little cooler in the wake of the cold front Sunday with
a reinforcing shot of cold air as a secondary cold front exerts a
glancing blow mainly to the northeast portions of the area. As
previously mentioned there will likely be around a 10 degree
gradient from the warmer Ozarks to the cooler Evansville tri state
area. Otherwise high pressure will return for mid week as
temperatures return to near normal. Another weak system is progged
to move through Thursday that could bring a chance of precipitation.
Currently the models indicate it will be moisture starved and bring
little more than clouds and slightly cooler temps except for the
ECMWF which continues to rain but it also has decreased amounts and
coverage from run to run. Therefore opted to leave mention out at
this time. However models are hinting at another system to move
through super bowl weekend but timing is very uncertain that far
out.

&&

.AVIATION...
Issued at 1115 AM CST FRI JAN 23 2015

Generally vfr conditions are expected to continue at the taf sites.
The exception is kpah, which will be on the northern edge of the
precipitation shield associated with the storm system to our south.
There will likely be periods of mvfr vsbsys in snow and rain at kpah
this afternoon. Otherwise, skies will become clear from west to east
early this evening. Northeast winds from 5 to 10 knots will become
calm tonight, then pick up from the west/southwest on Saturday
morning.

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
MO...NONE.
IN...NONE.
KY...NONE.
&&

$$

SHORT TERM...JP
LONG TERM/FIRE WX...KH
AVIATION...MY