Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 201935

Area Forecast Discussion
National Weather Service Paducah KY
235 PM CDT Tue Mar 20 2018

.SHORT TERM...(Tonight through Friday)
Issued at 226 PM CDT Tue Mar 20 2018

Cyclone energy induced rain/snow mix this pm is allowing falling
(frozen) pcpn to mostly melt this pm, so minimal impacts are
occurring. This should remain the case during these daylight
hours, with temperatures above freezing, and dew point depressions
ranging upwards to 10F in some spots in our north.

After nightfall, concern grows with cooling blayer temps, however,
best mean rh profile and energy works east. Drier air working
down the column shuts off the big flake potential as well. Will
continue with the Pop and the associated SPS for potential
minor impacts, but stay shy of accumulations/headlines. This
strategy has worked well thus far, and think it will into the
evening too.

Tmrw looks improving, but the continued back side of the cyclone
input flow leans us toward a slightly more pessimistic sky
forecast than numerical guidance would suggest. We`ve slightly
massaged (within the collab pic) the forecast sky and temps to
account for that consideration.

Thursday-Thursday night sees our next development/system to bring
Pops. The builder input temps are warmer, so any freezing/frozen
chances are now north and east of the FA. As such, chance showers
prevails to end the work week.

.LONG TERM...(Friday through Monday)
Issued at 312 AM CDT Tue Mar 20 2018

The long term period begins with above average confidence owing to
relatively good model agreement. However, confidence drops off over
the weekend into early next week with greater model variability.

An unsettled pattern will prevail from late this week into early
next week with multiple chances for showers. The period will start
with an upper level ridge centered over the Plains flanked by
troughs in the east and west. The ridge will translate eastward
through the weekend, placing the forecast area in southwest flow
early next week.

The first chance for showers arrives late Friday, Friday night, and
Saturday as energy over the Intermountain West tops the Plains ridge
and streams eastward into the Ohio Valley. At the surface, low
pressure over western Kansas late Friday is forecast to weaken as it
slides east along a baroclinic zone into the immediate forecast area
by Saturday evening. Rainfall amounts during this period are
forecast in the one quarter to one half inch range, with the higher
totals north of the front in closer proximity to Interstate 64.

By Sunday, the front is forecast to stall out south of the region.
Another low pressure system is forecast to develop over the Central
Plains and eventually lift the front north across the area as the
low moves northeast towards the Great Lakes. This will eventually
result in our next chance of precipitation, but how quickly all of
this transpires is unclear at this time. Both the ECMWF and GEM keep
dry conditions in place from Sunday through Monday evening with a
strong upper level ridge in place over the Southeast. Meanwhile, the
GFS is quicker to shift the ridge to the east and brings potentially
heavy precipitation into the area by Monday. Both the ECMWF and GEM
delay that potentially heavy precipitation until mid week. Given the
uncertainty, will stay close to the initialized model blend, which
keeps rain chances generally at or below 50 percent Sunday night and

A look at temperature guidance reveals a spread of as much as 15 to
20 degrees between the 00Z GFS and ECMWF MOS guidance late in the
weekend and early next week. The current forecast relies heavily on
a model blend, which smooths out the extremes from the individual


Issued at 226 PM CDT Tue Mar 20 2018

Showery pcpn under restricted MVFR and at times, IFR cigs will
prevail thru much of the pm, and into the evening hours,
particularly east. This includes the chance of frozen pcpn, but
impacts are minimal with surface temps remaining above freezing.
Clouds may improve to VFR with time, mainly during the second half
of the forecast time, but cigs will linger thru the entirety of
the package.



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