Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 221757

Area Forecast Discussion
National Weather Service Paducah KY
1257 PM CDT FRI APR 22 2016

Issued at 1254 PM CDT Fri Apr 22 2016

The AVIATION section has been updated for the 18Z TAF issuance.


.SHORT TERM...(Today through Sunday night)
Issued at 254 AM CDT Fri Apr 22 2016

The main band of showers and thunderstorms near the weak cold
front will push out of west Kentucky shortly. Meanwhile, some
widely scattered light showers rotating around the upper low may
sneak east southeast along the I-64 corridor through sunrise.

The upper low is expected to move east southeast across
central/southern Indiana today. With temperatures climbing into
the low to mid 70s and the 850mb cold pool moving through the EVV
Tri State today, some sufficient shallow instability may develop
to support isolated to scattered shower activity possibly
beginning before 18Z. This activity will be mostly confined to the
east of a line from Albion Illinois to Henderson and Calhoun
Kentucky. However, by mid-afternoon NAM soundings indicate that
a few light showers may develop westward across much of southern
Illinois. Far northeastern areas...mainly Pike...Warrick and
Spencer counties in Indiana...may even be able to eek out some
deep instability to support a thunderstorm or two around 18Z.

Any convective activity this afternoon should be done before 00Z,
and the remainder of the short term forecast is dry. All available
00Z guidance keeps the region dry Sunday night and even into
Monday, so removed the PoPs that were previously forecast for
Sunday night.

As for temperatures, did not stray far from the consensus of guidance
for highs today. Clear skies and relatively light winds tonight
should allow temperatures to drop to the lower end of the guidance
envelope for lows tonight. With high pressure in control at the
surface and aloft Saturday and Saturday night, we will be playing
a larger diurnal range by going on the high side of guidance for
highs Saturday and the low end for lows Saturday night. South
winds should kick in pretty well on Sunday, and temperatures
should find the high side of the guidance again. The winds will
stay up Sunday night, so it will be much milder with lows near 60
in some locations.

.LONG TERM...(Monday through Thursday)
Issued at 254 AM CDT Fri Apr 22 2016

Medium confidence for the extended. High confidence in a wet week

Models have meandered from starting rain chances as early as Sunday
night to Tuesday. They are now convening on the later start time and
I have pushed the start time back until Monday night at the earliest.
However this system is going to come through and bring showers and
storms to the area next week. The real challenge how soon it arrives
and departs which is always a problem with blended ensemble runs.
They typically extend the residence time of precipitation since it
takes in so many different solutions and averaging and weighting.
This is especially true with summer time convective events. A weak
cold front will meander or drift slowly south toward the heartland
out ahead of broad upper low. This boundary will stall over or near
the area early in the extended and is the reason for the flip
flopping of the start time of the rain. Any rain associated with
this front will be of low impact if any. When the upper low and its
surface reflection of yet another cold front arrives thats when the
best chance of storms will arrive. The timing of the main system
should be here Wednesday into Wednesday night. We have a very strong
cap between 5 and 10k feet until Tuesday. This may be enough to hold
off precipitation at least in the south until Tuesday. May have to
blend a little in the north and west for collaboration as far as
pops go but will take a wait and see for that. Otherwise Wednesday
appears to be the best instability parameters with LI`s negative 4
and CAPE`s anywhere from 800 to 1500 j/kg2. There is even some
elevated instability with K index values exceeding 30. The freezing
level is well above 10k feet but the wet bulb freezing level is
around 7k feet. This combined with 45 knot unidirectional winds at
850mb would expect any severe threat should remain to be wind or
hail Wednesday.


Issued at 1257 PM CDT Fri Apr 22 2016

Widely scattered shower activity will continue through at least mid
afternoon at/near KEVV and KOWB TAF sites as the upper low and
daytime surface heating interact with colder air aloft. Broken VFR
ceilings - occasionally at MVFR levels - can be expected at KEVV and
KOWB until late afternoon when clouds will lessen as daytime heating
subsides. Northwest winds will gust into the teens at all sites
through the day, but as surface high pressure settles overhead,
winds will diminish considerably tonight. Light winds tonight may
allow for fog or low cloud formation late but will continue to keep
it out for now. However, if winds go calm expect some adjustments
for later TAF issuances. Mainly clear skies and NNE winds around 5
knots can be expected Saturday.


.PAH Watches/Warnings/Advisories...


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