Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 221818

Area Forecast Discussion
National Weather Service Paducah KY
118 PM CDT Mon May 22 2017

.SHORT TERM...(Tonight through Wednesday night)
Issued at 109 PM CDT Mon May 22 2017

Goes-R hi res vis shots indicate high clouds across eastern two
thirds of FA, with additional mid-high clouds just upstream as
well. According to time/height cross sections, these should be
the only clouds over the course of the next 12 hours or so, as
surface High pressure continues its migration up Ohio river

Return flow slys develop later tmrw pm/evening, allowing some
better/deeper seeded moisture to move in, with evolving long wave
Low pressure/trof poised to affect the FA. This system will drive
a cold front into/across the area Tue night-Wed morn, resulting
in scattered showers/chc thunderstorms preceding and with its

Temps will remain largely in the 70s/50s til the reinforcing cool
shot of air Wed yields 60s for Highs.

.LONG TERM...(Thursday through Monday)
Issued at 109 PM CDT Mon May 22 2017

High confidence early in the extended. Confidence falls into the
medium level over the Holiday weekend. Finally the models diverge
drastically Memorial Day but they keep us dry at this time.

We will start the extended mainly dry...may have to keep a chance or
sprinkle in the Pennyrile area early. Then we have some subtle
ridging aloft building in for Friday. This combined with a major cap
or inversion leads to high confidence in a dry Friday. Saturday a
warm front lifts north of the region placing us in the warm sector
with a cold front to our northwest. There will be weak
perturbations in the flow aloft that could spark thunderstorms
depending on how strong the ridging may be. There are some
discrepancies with the strength of the ridging. Expect the
forecast builder to average between the models and likely yield at
least low pops for the Holiday weekend. Finally as we get into
Monday the models really diverge. The GFS has the surface low over
northern Illinois with a cold front arced across the area, while
the ECMWF has the low over the northeast with cold front along the
east coast. The forecast soundings keep a strong cap over the
area through the day around 750mb with fairly shallow moisture.
However there is plenty of instability with GFS With Li`s
approaching double digits and surface based CAPEs to around 2k
j/kg2. The ECMWF forecast soundings are not as unstable but do
agree on shallow moisture. Expect temperatures to climb into the
middle 80s for highs for the Holiday weekend and dew points at
least into the middle 60s.


Issued at 109 PM CDT Mon May 22 2017

Mid-high clouds will be SCT-BKN at times thru the package,
but generally increasing in scope late in the planning period.
Light winds will gradually veer with time, as surface high
pressure migrates up the Ohio river valley and a developing Low
pressure storm system aloft approaches from the west.




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