Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 161713
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
1113 AM CST Tue Jan 16 2018

.SHORT TERM...(Today through Thursday night)
Issued at 224 AM CST Tue Jan 16 2018

Ongoing Winter Storm with impressive snowfall accumulations across
the area will have to be extended this morning. The main thing we
see is top down saturation on the soundings continues especially
in the dendritic growth zone, and with nearly 20 to 1 ratios, just
a little qpf goes a long way after multiple hours of snowfall.
Expect another inchor two in our east and southeast, so based on
radar trends, we`ll have to linger the warning there thru mid
morning. This was collaborated and will align well with our
neighbors.

In addition, the wind/arctic air mass will be producing wind
chills to Advisory criteria or very near it, over all but the
farthest southeastern counties. As a result, we will fill in the
hole, so to speak, and expand the Advisory southward. This was
collaborated and will likewise align better with our neighbors.

Another bone chilling night is on tap tonight, but by then surface
High pressure has extended its incoming grip and winds have begun
to relax. We did undercut guidance a little on temps, particularly
Lows, from the blended nos.

Temps do not actually rise above freezing again until Thursday.
Thursday will also offer the best chance/most sunshine, with the
surface High pressure anchored across the lower Mississippi river
valley, so the combined effect should help improve our
treacherous road conditions on that day in particular.

.LONG TERM...(Friday through Monday)
Issued at 224 AM CST Tue Jan 16 2018

Forecast confidence remains higher than average through much of the
long term owing to continued good agreement among forecast models.

A moderating trend will carry over into the weekend as southerly
flow strengthens between high pressure over the Southeast and
developing low pressure in the lee of the Rockies. In the upper
levels, a relatively flat flow pattern on Friday will become strong
southwesterly over the weekend in response to an approaching storm
system over the Plains. High temperatures should make 40 degrees on
Friday, then above 50 Saturday and Sunday. Temperatures may even
approach 60 by Sunday.

With an increase in low level moisture amidst a large scale warm
advection pattern, clouds should be plentiful over the weekend.
Substantial rain is not expected until Sunday, but forecast
soundings suggest the potential for some very light rain or even
drizzle by Saturday night. Rain chances peak Sunday afternoon into
Sunday night as large scale forcing for lift brings about better
moisture return ahead of the approaching low and cold front.

While this precipitation event is forecast to be all rain, it will
be warm enough that thunderstorms may become a factor. With such a
dynamic system and at least some marginal instability per model
MUCAPE projections, there is at least some concern for a QLCS type
event late Saturday afternoon and evening, especially in southeast
Missouri. As a result, we have added a slight chance mention of
thunder to the forecast in southeast Missouri Sunday afternoon and
evening. It is not clear as to how much instability will remain
further east, but models suggest it should diminish heading later
into the nighttime hours Sunday.

The precipitation should taper off from west to east across most of
the area late Sunday night, but a few showers could linger into
Monday morning over eastern sections. The good news is that the air
mass that follows will not be nearly as cold as what we`ve had of
late. In fact, guidance suggests temperatures should cool down to
just near normal early next week behind the front.

&&

.AVIATION...
Issued at 1114 AM CST Tue Jan 16 2018

Cold air stratocumulus rotatinbg around the upper trough axis as
it swings through the WFO PAH TAF sites will generate periodic
MVFR ceilings with intermittent snow showers. With the 18z Tuesday
WFO PAH TAF issuance, there was a strong consideration to use
TEMPO groups for the MVFR visibility restrictions due to snow, but
given the chaotic banding nature of the Stratocumulus, decided to
place 4-5 statute miles visibilities in prevaing forecasts for
this afternoon and evening. The visibilities and ceilings should
improve markedly after 06z Wednesday as trough axis moves through
the WFO PAH TAF sites.

As warm air advection moves in from the west, brought in a lower
MVFR ceiling to address stratocumulus/stratus developing as
insolation enhances the mixing for additional cloud development.

&&

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

$$

AVIATION...Smith



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