Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 161143
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
743 AM EDT Wed Oct 16 2019

.UPDATE...
Issued at 743 AM EDT WED OCT 16 2019

Based on obs upstream, an early morning update was sent with an
increase in winds speeds with the cold fropa.

&&

.SHORT TERM...(Today through Thursday)
Issued at 500 AM EDT WED OCT 16 2019

At 4 am a strong cold front was located from KCVG to KBWG and was
moving southeast. It is supported by a potent but progressive
upper level trough stretching from a closed low over Lake Michigan
southwest through the middle Mississippi Valley. The system was
producing ongoing showers over the JKL forecast area. There have
been a few thunderstorms fueling off of elevated instability
during the night, especially over central KY, but they have mostly
died out early this morning.

The cold front and upper trough axis will sweep through early
this morning. This will bring much cooler air in at the low
levels, and much drier air aloft, cutting off convection and
putting an end to precip. However, steep low level lapse rates
will keep some shallow stratocu around into tonight, especially in
our northeast counties. As surface high pressure builds in from
the west on Thursday, a continued decrease in clouds is expected,
with mainly clear skies by evening.

Dew points are expected to drop down to the mid 30s tonight, and
with this afternoon`s temperatures only expected to be in the 50s,
it raises concern again for frost. However, the cold air advection
may make it difficult to decouple, and clouds could also inhibit
radiating in some places. All things considered, only patchy frost
has been placed in the forecast. Day shift will need to reevaluate
for the possibility of a NPW.

.LONG TERM...(Thursday night through Tuesday)
Issued at 455 AM EDT WED OCT 16 2019

The models are in decent agreement with the upper level pattern
through much of the extended. The period will begin as an upper
level closed low over the northeastern CONUS continues to progress
eastward. Meanwhile, ridging will build in over the Ohio Valley
Friday afternoon. This will persist through Saturday morning
before a small shortwave moves over the state in the afternoon and
into early Sunday. Generally zonal flow over Kentucky Sunday will
then give way to an approaching stout upper level trough from the
central Plains on Monday. However, model discrepancy increases by
early next week.

At the surface, high pressure will be the main story through much
of the weekend. However, a surface low pressure system will begin
to build and progress eastward on Sunday. The warm front
associated with this low will move northward over Kentucky by
Monday morning. From late Monday into early Tuesday, a cold front
will progress over the state as well. Surface high pressure will
then build back over the region for midweek.

In terms of sensible weather, the period will begin dry. Some
slight chance to chance PoPs will be possible late Saturday
afternoon through Sunday as a weak upper level disturbance moves
over the region. The main source of precipitation will come Monday
evening through Monday night with the passage of a cold front.
According to model soundings, there will be the potential for a
few thunderstorms Monday afternoon and evening as well, but
instability is lacking as a whole for this early week system.
Model uncertainty also increases early next week, as the GFS and
ECMWF are out of agreement with the onset of precipitation from
cold FROPA Monday into Tuesday. However, this will continue to be
monitored with future model runs.

High temperatures will be in the lower to upper 60s Friday
afternoon but then gradually increase to be in the mid to upper
70s by Monday. However, due to cold FROPA, highs will dip back
down into the 60s Tuesday. Low temperatures Friday morning will be
in the lower to upper 30s, with the valleys cooler due to light
winds and clearing skies. Patchy frost will also be possible in
areas late Thursday night into Friday morning due to these
temperatures. Saturday morning lows will be in the upper 30s to
lower 40s. Some areas of patchy frost will again be possible in
the colder valley locations. Although, the better chance at frost
development will be early Friday morning. Lows temperatures will
then be in the mid 50s by Monday morning; but with FROPA, Tuesday
morning lows will be slightly cooler, with values in the upper 40s
to lower 50s expected.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
ISSUED AT 242 AM EDT WED OCT 16 2019

A cold front was approaching from the northwest late tonight. It
was causing showers to be on the increase across the area at the
start of the period, and they will affect all areas overnight. There
will also be some thunderstorms mixed in. A general deterioration
to MVFR is forecast with the showers, with some IFR at times,
especially right behind the front early Wednesday morning. As
colder and drier air arrives, rain will end from northwest to
southeast on Wednesday morning, and clouds will start to break up.
Ceilings will be lost over much of the area on Wednesday
afternoon, but VFR ceilings may linger over the northeast part of
the forecast area into the evening (including KSYM AND KSJS).

Winds will shift from the south southwest to the northwest with
frontal passage early this morning, and increase to around 10
kts, with some higher gusts possible.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...HAL
SHORT TERM...HAL
LONG TERM...CGAL
AVIATION...HAL



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