Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 210900
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
400 AM CDT Sun May 21 2017

.SHORT TERM...(Today through Tuesday night)
Issued at 338 AM CDT Sun May 21 2017

Drier air will continue to slowly ooze east into the region today
as high pressure gradually builds into the Southern Plains. Skies
will gradually clear from west to east...though it may take til
later this afternoon for the Pennyrile areas of western KY to
clear out. lowering sfc dew points and light northerly winds will
bring a much cooler night tonight. A few locations along the I-64
corridor may even see temps dip to near the 50 degree mark.

Monday should be a pleasant day as high pressure continues to
build east into the Ohio River Valley. Most of the region will see
highs in the mid 70s with very comfortable humidity levels.

An upper level trof and associated weak surface front are
forecast to approach the region as we head into Tuesday/Tuesday
night time frame. This will result in a return of of shower/isolated
thunderstorm chances, though nothing of the magnitude some locations
saw yesterday.

.LONG TERM...(Wednesday through Saturday)
Issued at 338 AM CDT Sun May 21 2017

Quite a large change in the upper-level pattern will occur during
the long term. The 500 mb map will start off with a deep trough over
the Mississippi Valley on Wednesday, then transition to a broad
ridge in the same area by Friday. The resultant change in our
sensible weather will be large. Details follow...

On Wednesday, a cool northwest surface wind will be associated with
the deep trough aloft. There will likely be considerable cloudiness
due to the cyclonic low-level flow and cold air aloft. The models
are not especially moist in the low levels, with surface dew points
near 50. Even short periods of sun would bump up temps to near 70,
allowing for some weak diurnally-induced convection. Isolated
thunder is possible in the afternoon, but mainly showers are
expected.

On Thursday, subsidence will increase as the trough moves east and a
500 mb shortwave ridge moves east across the Plains. There will be
less cloudiness than Wednesday, but a persistent northwest wind will
not allow temps to get much above 70.

The shortwave ridge will move across the Lower Ohio Valley on
Friday, accompanied by a warmer and increasingly humid south
surface wind flow. The models indicate there will be strong warm
advection aloft on Friday and Friday night, with 850 mb temps
rising about 10 degrees Celsius over 48 hours. Some elevated
instability will develop by Friday afternoon, and a few elevated
showers and storms are possible through Friday night.

By Saturday afternoon, our region will be under a southwest flow
aloft in the wake of the mid-level ridge. A surface low will develop
over the Plains, placing our region in a broad warm sector covering
the mid-section of the country. There will be mcs activity within
the moist and unstable warm sector, but the models vary with respect
to the timing and location of each mcs. The first part of the
Memorial Day weekend looks rather warm and humid, but there is not
much model agreement on precip chances. The forecast will contain
slight chance pops for day 7, which conforms to the multi-model
blend.

&&

.AVIATION...
Issued at 1202 AM CDT Sun May 21 2017

Will maintain forecast of unrestricted CIGS/VSBYS through the TAF
period. Shower chances have lessened at KEVV and KOWB and have
removed vicinity showers there. Expect generally scattered 1 KFT
clouds at KOWB and KEVV with brief ceilings possible. Winds will
shift to the NW overnight/early Sunday as a cold front passes each
TAF site.


&&

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

$$



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