201 
FXUS63 KPAH 100525
AFDPAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
1125 PM CST Mon Dec 9 2013

.UPDATE...
ISSUED AT 1125 PM CST MON DEC 9 2013

Updated for 06Z aviation forecast discussion.

&&

.SHORT TERM...(This Evening through Wednesday)
ISSUED AT 1256 PM CST MON DEC 9 2013

The primary forecast challenge is the snow event tonight-early
tmrw morning. In a nutshell, there is not alot of change that we
are seeing from the 12Z guidance to make any more than cosmetic
changes to the going package. One such cosmetic change will be to
bump the main swath area from likely to categorical pops, namely
for our northern most strip of counties along I-64 in southern
Illinois. 

QPF is similar if unchanged, with higher SLR on the order of 17 to
1 producing the forecast amounts in the highest areas of 1-1.5
inches. This will have little impact on the areas it is falling
upon save for the reduction in vsby for a 3-4 hour window, so
we've followed up the previously issued SPS with a similar one.
This was coordinated/collaborated with LMK and adjacent nearby
offices appear to be in agreement as well.

This zone of pcpn should be entirely east of the PAH FA by 15z
Tuesday, after which cool/dry high pressure migrates across the TN
valley. Teens for lows and 30s for highs look good through the
remainder of the short term portion of the forecast.

.LONG TERM...(Wednesday Night through Monday)
ISSUED AT 224 PM CST MON DEC 9 2013

Cold high pressure at the surface will be in control at the onset of 
the extended period. There should still be some snow/ice on the 
ground. Models have trended slightly colder for highs Thursday and I 
have reflected this but maybe not to their extent.

The next storm system moves toward the region on Friday. GFS remains 
slow in bringing in precipitation, holding til later in the 
afternoon. The ECMWF is about 6 hours faster but is a little slower 
than its 00Z run. Temperatures are above freezing at the onset of 
precipitation and have all liquid during the day. Friday night is 
more questionable. Have temperatures falling just below freezing in 
the northwest 1/2 of the forecast area and therefore have a mix of 
rain and freezing rain. Soundings show temps right around freezing 
in this area with a warmer layer just off the surface. Soundings in 
the south show temps above freezing during the event.

Rain tapers off on Saturday and comes to an end Saturday night. 
Precip may be a mix of rain and snow over the northeasternmost 
counties before coming to an end. Cold high pressure then builds in. 
Models vary on the degree of the cold air.  The ECMWF has a much 
sharper trough and much colder air and have followed our neighbors 
and trended this way. 

&&

.AVIATION...
ISSUED AT 1125 PM CST MON DEC 9 2013

Light snow currently moving across parts of the area. Cigs have
yet to lower at the TAF sites but they are expected to lower to
MVFR with time. Vsbys might lower in the heavier snow bands,
especially at KEVV/KOWB. The snow will likely end by 12Z but the
lower cigs may take a few hours longer to lift. It appears as
though by 18Z, cigs should rise to VFR for the rest of the TAF
period. Winds will be northwest early in the period and shift to
more west or southwest by Tuesday morning. 

&&

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

$$