Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 210746

Area Forecast Discussion
National Weather Service Paducah KY
246 AM CDT Tue Mar 21 2017

.SHORT TERM...(Today through Thursday night)
Issued at 230 AM CDT Tue Mar 21 2017

The frontal boundary is now straddling western Ky, and the models
have had a good grasp on its placement for the last 12 hours or
so. They sag it just south of the FA by 12Z, after which,
convective chances start to initiate via warm air
overrunning/elevated instability, as the leading dynamical energy
aloft starts to spill in/overtop the boundary. This Marginal to
Slight Risk Svr activity really picks up during the pm/evening
hours, as the vort energy increases its affect with the
approaching jet streak. The activity by then may gain some surface
based instability, but the latest modeling keeping us north of
the boundary suggests the primary initial hazard is hail, with the
potential for wind damage if evolution of the cluster storm
genesis area results in mesoscale driven surface based activity.
Lightning and heavy rain, with PW`s at the 90th-95th percentile
around 1.2", will be commonplace storm associated hazards. The
overall convective feed ends north to south overnight as
drier/cooler air invades the column via the Canadian CP airmass
driven by surface High anchoring over the Great Lakes and
extending its reach southward and eastward across the Ohio river
valley. Temps well into the 60s today, with dew points nearly so
not far off, will cool close to 15F tmrw, before moderating up
again another 5-10F Thursday as the High shifts its anchor

.LONG TERM...(Thursday through Monday)
Issued at 320 PM CDT Mon Mar 20 2017

We expect clouds with a warm frontal passage Thursday. The ECMWF and
NAM are drier, with a little more moisture seen on the CMC and GFS
models. Kept a slight chance of showers in mainly SEMO as weak
energy moves through in the mid levels. Thursday night should be
dry. May be a lingering shower or sprinkles in the evening. But PoPs
too low to mention for now.

Friday through Saturday, the model consensus is a H5 low will move
east from nation`s mid section, to over the Ozarks and MO from 12z
Friday through 18z Saturday. Most of Friday should be rain free
(exception area Ozarks region SEMO), with PoPs ramping up Friday
night through Saturday as the system approaches. Showers and
possibly isolated thunderstorms. PoPs will lower Saturday night
through Sunday as the system starts to move to the northeast into
the Ohio Valley region. For now, used a blend of the EC/GFS and
their ensemble mean solutions for timing and movement of this
system. Used a blend of EC/GFS and CONSraw (model blend) for
temperatures for the entire 4 day extended period.


Issued at 230 AM CDT Tue Mar 21 2017

A frontal boundary straddling western Ky will remain south of the
terminals today, nuzzling toward/just south of the Ky/Tn border,
but be the focus for overrunning clouds/convection, esp this
pm/evening. Cloud cover may range from VFR to MVFR at times, esp
with relation to daytime convective chances, with vicinity
mentions for the peak pm-evening hours. PCPN chances and flight
restricted CIGS/VSBYS are most likely closer to the boundary, i.e.
southwest (KCGI/KPAH), with diminishing chances northeast
(KEVV/KOWB). Clear-out/Improving conditions tonight will work in
reverse order (northeast to southwest) as High pressure invades
the column with cooler/drier air from the Great Lakes toward the
lower Ohio river valley.




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