Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 152035

National Weather Service Jackson KY
435 PM EDT Sat Jun 15 2019

.SHORT TERM...(This evening through Sunday night)
Issued at 435 PM EDT SAT JUN 15 2019

Current surface analysis shows a low pressure system over Iowa,
with a surface front over the upper Ohio Valley and a cold front
extending down over the central Plains. This system will be slow
to progress eastward over the next couple of days. Mainly zonal
flow will be present aloft, and a series of shortwaves will also
move over the Ohio Valley. Chances for showers will thus increase
from the northwest this evening and overspread eastern Kentucky
into tomorrow.

With the stagnant pattern, showers will then persist through the
beginning of the work week. Furthermore, model soundings show an
average of 3000 J/kg MUCAPE for Sunday afternoon. MUCAPE on Monday
is close to this value too; therefore, each day will see fair
chances for thunderstorms, particularly during peak heating in the
afternoon and early evening. With PWATS generally between 1.5 and
1.8 inches, there will be the potential for localized flooding in
the stronger storms as well.

After high temperatures today in the lower 80s, low temperatures
in the upper 60s are expected into tomorrow morning. This pattern
will then continue for Sunday afternoon and Monday morning, with
highs in the lower to mid 80s and lows in the upper 60s.

.LONG TERM...(Sunday night through Friday)
Issued at 432 AM EDT SAT JUN 15 2019

Ongoing zonal flow will be disrupted to start the period as a
pronounced shortwave develops over the south-central Plains along
with an upper level low pressure system. This will shift eastward
towards the Ohio Valley throughout Sunday night, with lowering
heights expected across the state. The shortwave will slow and
nearly stall, not passing over the Commonwealth until mid-week, at
which time it will be weakening. Another shortwave will then work
its way into a trough, passing across the eastern Conus Thursday and
Thursday night. Ridging will begin to take hold across Ky for
Thursday as the trough exits, however, this will be short-lived as
another shortwave quickly develops and passes through the ridging
pattern, across the state Friday into Saturday.

The above-mentioned upper level disturbances will also be
accompanied by surface features that will translate to an active
period. A stationary front will be located north of the Ohio River
through the day Monday, shifting slightly farther southward and
closer to the river for Tuesday. Kentucky will be within the warm
sector, with southerly winds promoting a warm and humid airmass.
This airmass, and the close proximity of the stationary boundary
will lead to likely shower and thunderstorm chances each day,
especially during peak heating in the afternoon. Better instability
will be lost overnight. SPC currently has the entire state in a
marginal risk for severe thunderstorms from Monday through Tuesday
morning given this placement. Precip chances will increase further
on Thursday, as an area of low pressure passes from SW to NE along
the Ohio River, increasing the Srly flow and creating a more
concentrated source of lift. A frontal boundary will likely follow,
with high pressure filling in behind. However, this will not
necessarily translate to dry weather. The shortwave passing over
during the weekend may continue to promote at least chances for
showers/thunderstorms, especially during peak heating.

Despite the deep SW flow throughout the period, the influx of
moisture in the form of clouds and precip will keep temperatures
from reaching true potential, with highs in the upper 70s and low
80s each day. However, humidity will consequently be high as a
result. NBM continues to struggle with many of the forecast elements
it populates for. Ended up trending many of higher elevation winds
down to better mimic normal expectations. Also made considerable
updates to the pops to better line up with the current GFS and ECMWF
forecasts (and NAM in the mid-term). Also reran thunder to better
match up with the latest GFS-20 soundings.


.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)

A surface low pressure system is slowly making its way towards
the Great Lakes, with a surface front draped over the upper Ohio
Valley. This system is expected to progress to the southeast,
causing the front to slowly push southward as well. Thus, chances
of showers and the potential for thunderstorms will increase later
this evening, mainly for areas north of I-64. Shower and storm
chances will then expand to areas further south, mainly along and
north of the Mountain Parkway, through Sunday. Have included
mention of at least VCSH for SYM this evening and also for JKL and
SJS tomorrow morning to account for this. Meanwhile, southwest
winds this afternoon will be fairly strong, with sustained winds
between 10 and 15 knots. Gusty winds up to 25 knots are also
expected. In fact, the SYM site observed a 25 knot wind gust
earlier this morning. Winds will then decrease later this evening
to be below 10 knots for the overnight. Another concern will be
for LLWS during the overnight tonight. A fairly stout low level
jet will set up over eastern Kentucky, bringing around 40 knots of
LLWS by 4Z that will persist through the early morning hours. By
13Z, however, this is expected to diminish. Lastly, some gusty
winds up to 25 knots are likely by tomorrow afternoon.




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