Area Forecast Discussion
Issued by NWS Paducah, KY

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258
FXUS63 KPAH 121148
AFDPAH

AREA FORECAST DISCUSSION
National Weather Service Paducah KY
548 AM CST FRI FEB 12 2016

.UPDATE...
Issued at 548 AM CST FRI FEB 12 2016

Not a fun morning to keep up with radar trends. Currently have IFR
snows over southeast Illinois that are drying up fast as they
cross the Wabash according to KVWX. Considered issuing a quick
advisory for the EVV area, but with those radar trends, figure the
SPS will suffice. We are now up to one report of snowfall this
morning.

The AVIATION section has been updated for the 12Z TAF issuance.

&&

.SHORT TERM...(Today through Saturday night)
Issued at 318 AM CST FRI FEB 12 2016

A nice band of light to briefly moderate snow has developed as
advertised by almost all short range guidance, just to the
northwest of a KCGI to KPAH to Cadiz, KY line. Used that consensus
as the starting point for hourly PoPs this morning. If anything,
it appears that the snows are making faster progress eastward
across the region. IFR level snows have been observed from KMDH
and KMWA to KM30 and K5M9, but we have not received any snowfall
reports to really get a feel for how much it is accumulating.
Given the rather short residence time at any one location, the
general amounts advertised by the evening shift, up to an inch,
seems reasonable. Will not be issuing an Advisory, but will
continue with the SPS treatment.

Of less certainty is the impact associated with a separate area of
light snow moving east southeast from the KSTL metro area.
Pops were increased to low end likely levels generally along
I-64. It should make it to the Wabash by 12Z and then fizzle out.
This may be overdone, given latest radar trends with the snow
eroding on its southwest side. Any impactful snow may pass just
north of our CWA. Will also try to address with the SPS.

The 00Z models have remained consistent in the Arctic surface high
building into the area this afternoon. This will result in gusty
northwest winds developing southward through the afternoon, but
the cold advection will not really get going until tonight.
Temperatures in the north may level off at some point this
afternoon, but a true non-diurnal trend is not expected.

With the surface high really building in tonight, skies should
clear and northwest winds will continue to gust. Strong cold
advection is expected, and the consensus of guidance brings lows
mostly in the 10-15 degree range. Some northern locations may see
single digits. Wind chills will bottom out from around 5 below
zero in the north to 5 above in the far south. Will give this a
mention in the HWO.

With a cold start and rapidly increasing clouds on Saturday,
temperatures throughout the region are not likely to climb out of
the 20s. Areas along I-64 and the EVV Tri State may even struggle
to reach 20.

The surface high will shift quickly east of the area heading into
Saturday night, allowing winds to become easterly. As our next
storm system digs southeast through the northern Plains, there is
growing support for some light snow to reach northern portions of
the forecast area by 12Z Sunday. The 00Z GFS and NAM were holding
the snow off, but the 06Z NAM is trending toward the more
aggressive and consistent ECMWF. Decided to introduce 20-30% PoPs
mainly over southern Illinois and northern portions of southeast
Missouri after midnight Saturday night. With easterly winds and
plenty of clouds, tried to go closer to the relatively warm ECMWF
MOS for lows Saturday night.

.LONG TERM...(Sunday through Thursday)
Issued at 318 AM CST FRI FEB 12 2016

The medium range models seemed to be in decent agreement overall
with the timing of a developing mid level shortwave responsible for
snowfall generation at the beginning of the extended period. On
Sunday, surface dewpoints should be on the rise as low level winds
will have some kind of southerly component. Meanwhile, low surface
pressure is forecast to develop and move across the Deep South, and
this feature was best depicted by the GEM/ECMWF. The 00Z ECMWF
continued with a general tendency to have greater QPF than the other
models, especially over western KY Sunday night. The initialization
blend provided modest QPF, with the highest numbers in western KY,
however not all of that will be frozen.

Model thermal profiles indicate the pcpn event will start out as
snow Sunday, with a chance of sleet late Sunday night as the column
begins to warm a bit. Monday morning, there should be a rather quick
changeover to rain, with rain forecast everywhere by the afternoon.
Any lingering pcpn Monday night may change back to snow before
ending. As expected, the forecast snow amounts have fluctuated from
forecast to forecast, and at this time it looks like a couple of
inches total of snow can be expected for the region in general,
which is less than what was forecasted 24 hours ago.

A second clipper-type shortwave is forecast to affect the PAH
forecast area for a brief time Tuesday. The pcpn should start out as
snow in the morning and change to rain later as surface temperatures
jump well into the 40s.

In the latter half of the week, rising mid level heights will
contribute to significant warming. Under mostly clear skies, highs
Thursday are expected to be in the 50s across the entire area.

&&

.AVIATION...
Issued at 548 AM CST FRI FEB 12 2016

IFR to MVFR snow will impact KEVV and KOWB for next couple of
hours, but VFR conditions should return quickly once the snow
ends. An Arctic surface high will surge across the area this
afternoon. This will lead to north or northwest winds gusting up
near 20kts, and MVFR ceilings. Lots of guidance indicating MVFR
ceilings well ahead of the Arctic air, but latest observational
evidence supports a later arrival. That said, once they arrive
they may linger well into the evening before scattering out. The
gustiness will also settle down through the evening.

&&

.PAH Watches/Warnings/Advisories...
IL...NONE.
MO...NONE.
IN...NONE.
KY...NONE.
&&

$$

UPDATE...DRS
SHORT TERM...DRS
LONG TERM...DB
AVIATION...DRS



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