Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 210040 AAA

National Weather Service Jackson KY
840 PM EDT Sat Jul 20 2019

Issued at 717 PM EDT SAT JUL 20 2019

Outflow, from convection down in Tennessee from earlier, has
initiated some storms across portions of the Cumberland River
Basin through early this evening. Some of the updrafts have been
quite robust at times, taking advantage of the ML CAPE of 3000
J/kg in place. Consequently, raised PoPs through around 8 pm for
these locations. An outflow boundary continues to move north,
currently arced from London to Harlan; however, convective
initiation has been more spotty along it as it gets deeper into
our forecast area. Expect this activity to gradually wane as we
lose heating. Updates have been sent.


.SHORT TERM...(This evening through Sunday night)
Issued at 438 PM EDT SAT JUL 20 2019

It`s the same old story again today, with an upper level ridge
over the area, and a surface ridge to our south. The upper level
ridge was keeping a lid on most deep convection. However, deep
moisture was greater over our southern counties, and combined with
heating of elevated terrain, was resulting a few isolated showers
and thunderstorms. These should die out with a loss of surface
heating this evening, and most of the cu should also dry up.

The large scale pattern is undergoing changes, and this could
begin to affect our weather late tonight. A upper level trough is
developing over the Great Lakes, and our upper level ridge is
weakening. At the same time, deep moisture to our south is
expected to migrate northward overnight. The combination may lead
to showers and thunderstorms developing toward dawn and into the
day Sunday.

As the upper trough deepens, a surface cold front will move
southeast and likely be near the Ohio River by early Monday
morning. Models suggest that showers and thunderstorms during the
day on Sunday will probably deplete the atmosphere and largely die
out by evening. Thunderstorms which develop along the cold front
then have a hard time making it here during the night, with our
highest POP holding off until the long term period.

.LONG TERM...(Monday through Saturday)
Issued at 416 PM EDT SAT JUL 20 2019

The models are in good agreement showing an upper level trough
deepening as it progresses over the Ohio Valley from Monday
through Wednesday morning. Meanwhile, a large upper level ridge
will build over the western CONUS. By midweek, the trough will
move to the northeast and the ridge will build further east. At
the surface, a cold front will make its way over the Commonwealth
Monday, quickly progressing to the south early Tuesday. High
pressure will then build into the Ohio Valley, eventually shifting
to be to the east of Kentucky by late week.

This pattern will give way to showers for the start of the work
week. PWATs continue to be high in the GFS model soundings,
ranging from 1.90 to 2.15 inches from Monday morning through late
Monday evening. Thunderstorms will also be possible during this
time, with MUCAPE values around 2800 J/kg and some shear present
in the afternoon. However, storm chances are expected to dwindle
by late Monday evening. As the front exits early Tuesday, showers
will be on the decrease as well. Dry weather will then be the main
story through the remainder of the week.

Temperatures through the extended will be much cooler than recent
days. High temperatures will begin around 80 degrees before
dipping into the upper 70s through midweek due to FROPA. Highs
will return to the mid 80s by Friday and for the start of next
weekend. Lows will follow suit, starting in the low 60s Tuesday
morning. By midweek, lows will be in the 50s before returning to
the mid 60s Saturday morning. Furthermore, with light winds and
clear skies during the nighttime Wednesday through Friday, the
valleys will likely be cooler than the ridgetops.


.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)

Scattered convection will move off to the west and northwest of a
line from KSME to KLOZ through 01z. Once this exits, VFR
conditions will return through the rest of the evening, although
MVFR or worse fog may wind up being a concern at KSME, given a
more direct hit from the passing thunderstorms. Will have to
monitor this as we get deeper into the evening. River valley fog
will develop similarly to last night elsewhere through the night.
Clouds will then increase towards dawn, with at least a small
chance of showers threatening the area. Shower and thunderstorm
chances will generally increase through the day on Sunday, which
may eventually result in the a period of MVFR or worse conditions
at some point at most locations. Winds outside of thunderstorms
will average around 5 kts or less, generally out of the southwest.




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