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FXUS63 KPAH 092316

Area Forecast Discussion
National Weather Service Paducah KY
516 PM CST Mon Dec 9 2019

.SHORT TERM...(Tonight through Wednesday night)
Issued at 200 PM CST Mon Dec 9 2019

A cold front's passage later today into this evening will lead to
a big change in airmass, as highs today near or in the 60s plummet
a good 30 degrees tomorrow. During this transition, overrunning
moisture will create a window of opportunity for wintry pcpn,
changing light rain to light snow late tonight-early tmrw. WPC and
the blend/GEFS is consistently keeping only trace to a few tenths
of an inch (less than a half inch) across our extreme southeast,
despite some hints at deterministic 06z and 12z GFS amounts
slightly higher. But even looking more closely at the GFS, both
the gridded time/height cross section and sounding data for that
area around HOP reveals a large dry nose, in fact the 12z run 
increased its strength from 06z, coming in late tonight between
the boundary layer and about 600 mb. This should really impede 
accumulating potential, even with a wetter overall qpf/solution,
so we like the blended/ensemble approach this time with minimal
impact snows affecting mainly our western Kentucky counties around
the Lakes eastward, bordering the Tennessee border. Surface temps
there during the best time for snow will range from the mid to
upper 30s, and ground temps may be higher than that, two more
factors supporting minimal impact forecast.  

.LONG TERM...(Thursday through Monday)
Issued at 200 PM CST Mon Dec 9 2019

In the long term, collaborative efforts yielded an agreement to
utilize WPC qpf when the next moderating warmup/return chance of 
pcpn enters the forecast late in the week/into the weekend. Little
change off the blend occurs otherwise, as the models are fairly 
straightforward with the development of a Gulf Coastal trof that 
places us to the north of the main impact/pcpn field heading into 
the weekend. This is followed by a more zonal pattern in its wake,
with a clipper like wave of energy racing quickly across the 
Great Lakes Saturday, continuing our smallish pops thru the bulk 
of the days 5-7 period, even though much of that time period will 
actually be dry. Temps should be at/near climo norms, varying a 
few degrees on either side of the means.


Issued at 515 PM CST Mon Dec 9 2019

After discussion with the dayshift aviation forecaster, decided to
continue the trend of a slower rise of ceilings from IFR/MVFR to
VFR tonight and Tuesday and maintaining a lower scattered cloud
deck for moisture trapped within the post-frontal inversion. The
GFS numerical guidance seems to be closest with this solution. 

Lowest ceilings will likely remain associated with the passage of
the cold front into the area through at least 06z, as some post 
frontal boundary layer cooling and higher relative humidity is 
anticipated versus drier air intrusion aloft later in the night.



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