Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 192206
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
Issued by National Weather Service LOUISVILLE KY
506 PM CDT Wed Apr 19 2017

.SHORT TERM...(Tonight through Friday night)
Issued at 445 PM CDT Wed Apr 19 2017

Isolated showers and thunderstorms formed over TN and western KY
this afternoon. Based on satellite images of the cumulus field
today, this activity appears to be strongly driven by diurnal
heating. HRRR and other high-res guidance rapidly dissipates the
activity by around sunset.

Mainly clear skies are expected tonight following the dissipation
of today`s cumulus clouds. Low-level winds will be quite strong
from the south, averaging around 30 kts above 1 kft. Low temps in
the southerly flow pattern should be mainly in the 60`s.

On Thursday, a cold front will approach from the NW in the
afternoon. Model capes from the nam and gfs have been consistently
around 1500 j/kg in the afternoon. The mean wind flow in the 925
to 500 mb layer will average about 30 to 35 kt from the southwest.
This shear/instability combo may be sufficient for some isolated
intense convection near the front during the afternoon and early
evening. However, there is some potential for a band of widespread
mid-level clouds and showers to temper heating and destabilization
ahead of the front. In either case, rain chances Thu appear to be
categorical in parts of srn IL, tapering down to just a slight
chance in the khop area of western KY. Highs will range from the
mid 70`s in the cloudier areas of srn IL to the lower 80`s in
parts of west KY.

On Thursday night, the cold front will exit western KY after
midnight. T-storms will decrease with loss of diurnal heating,
then they will end in the wake of the front. Precip coverage
should gradually decrease, but showers will linger all night as
the 850 mb front hangs up across western KY. Lows will fall into
the 50`s.

.LONG TERM...(Saturday through Wednesday)
Issued at 445 PM CDT Wed Apr 19 2017

The period will begin with a cold front off to our south over the
Gulf Coast states. However, even with the front to our south, it
looks as there may be quite a bit of isentropic lift/overrunning
developing north of the front as a potent mid level shortwave
moves east into the Southern Plains Fri afternoon/Fri night.
Highest rain chances will be over the west half of the region,
though much of the rest of the area will likely get into the
overrunning rain shield by Sat morning.

12Z ECMWF has now trended a bit northward from the operational GFS
and UKMET with the track of the sfc low associated with the mid
level shortwave Sat/Sat evening. Will hold the coarse for now
with a forecast track just south of the KY/TN border. This would
keep most of the instability and severe thunderstorm risk south of
the region. Still quite a ways out in time though, so will need
to monitor model trends the next couple of days. If more support
comes the ECMWF`s way with a sfc low track into KY, it would bring
more of a t-storm threat to the region, especially over the
southern Pennyrile region of western KY.

One thing that looks more certain is that Sat will be a raw, damp,
chilly day, esp over the northern half of the region. Temperatures
may struggle to top even 50 up along the I-64 corridor. Will
likely not be a good day for outdoor enthusiasts. Sunday may see
some improvement as the system moves off to the east coast. If we
can get rid of pesky stratus associated with the upper low, Sun
afternoon may be salvaged.

On a brighter note, high pressure will finally settle back into
the region by early next week, bringing dry conditions back to the
region. The high will not be of Canadian origin, however, so
temperatures will stay on the mild side through the period.

&&

.AVIATION...
Issued at 445 PM CDT Wed Apr 19 2017

Diurnal heating of this moist air mass has resulted in scattered
to broken cumulus clouds this afternoon. Some areas of mvfr cigs
are likely early especially in the kevv/kowb areas. Cigs should
rise to vfr thresholds this afternoon as southwest winds increase
to around 10 kts. The cumulus clouds will quickly melt away with
loss of heating around sunset. Winds will decrease around sunset.

On Thursday, some mid clouds will overspread our region in the
morning. Southwest winds will become gusty by midday.

&&

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

$$

SHORT TERM...MY
LONG TERM...GM
AVIATION...MY



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