794
FXUS63 KJKL 092021
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
421 PM EDT Sun Jun 9 2024

.KEY MESSAGES...

- Shower and thunderstorm chances decrease through this evening.

- Hot weather arrives late this week, with highs in the upper 80s
  to lower 90s.

&&

.SHORT TERM...(This evening through Monday night)
Issued at 420 PM EDT SUN JUN 9 2024

Late this afternoon, an upper level low was centered over Quebec
with troughing extending south into the eastern Conus as well as
west across the Great Lakes to portions of the upper MS Valley.
Upper ridging extended from the Southern Plains into the Rockies.
At the surface, cold front continues to sag south across eastern
KY with boundary nearing the KY Highway 80 to Hal Rogers Parkway
vicinity. Convection was occurring generally ahead of the
boundary or along it from the Wise Co VA/Letcher county border
west to the Lake Cumberland region and on into parts of Central
KY. Instability is currently limited with MLCAPE of generally 250
J/kg across the south with near 500 J/kg near the KY/VA/TN tri
state area where recent lightning activity has been detected. At
the same time, drier air has advected in behind the front with
dewpoints falling to or even into the 50s further north.

Tonight and Monday, the axis of a shortwave trough moving across
the OH Valley region and through the eastern Conus trough shift
east and southeast this evening as the boundary drops south of
eastern KY. Another shortwave trough moving around the upper low
in Canada that meanders to the St Lawrence Valley and then
Maritimes should approach the OH Valley on Monday, working across
the area during the area during Monday afternoon and evening. At
the surface, a weakening secondary front in advance of this is
expected to drop into the OH Valley late tonight and then become
diffuse during the day on Monday southeast of high pressure
building south across the Upper MS Valley and western Great Lakes
and into the Lower OH Valley by late Monday. As the upper trough
from Canada and into the eastern Conus shifts east through Monday
and then Monday night, shortwave ridging will work across the
Plains and Central Conus and toward the Ozarks to mid MS Valley
to western Great Lakes vicinity to end the period. This leads to
a period of height rises from later Monday evening through Monday
night across eastern KY. At the same time, surface high pressure
builds into the OH Valley.

Convection in more southern locations should gradually wane
through early this evening and then shift south of eastern KY by
sunset if not earlier. Clouds are expected to decrease through the
night as a ridge of sfc high pressure noses into eastern KY
between the boundaries. Some valley fog will be a concern,
especially across the more southern valley locations where
convection is occurring at present or has occurred. A small to
moderate ridge/valley split is also expected especially further
north where the lower dewpoints are already advecting in.

Any fog should lift and dissipate within 2 or 3 hours after
sunrise on Monday with cold advection on Northerly to northwest
flow aloft as the next shortwave nears. Some increase in clouds
should occur ahead of this shortwave with generally shallow
cumulus, and at this point moisture is expected to insufficient
for any sprinkles or shower activity. These clouds should diminish
on Monday night as sfc and upper level ridging build into the
region and give way to rather cool temperatures for June, with
some of the normally cooler valley locations across the north
likely dropping to 48 to 49.

.LONG TERM...(Tuesday through Sunday)
Issued at 247 PM EDT SUN JUN 9 2024

There is good agreement among the ensembles and deterministic
guidance to begin the period. They show surface high pressure
building east into the Ohio Valley and even some shortwave ridging
noted in the mid-levels. This will keep the weather dry and
seasonable through around Wednesday. After this, high pressure
meanders east and mid- and upper level heights will be on the rise
once again leading to dry weather at least through Thursday.
However, warmer air advects into the area, with mean 850mb
temperatures from the EPS/GEFS/GEPS rising to near 18-19 C by late
week. This will give way to afternoon highs in the upper 80s to
lower 90s. However, by Friday there is some disagreement on a cold
front diving into the Ohio Valley in terms of timing and
location. The NBM keeps some slight chance PoPs (generally less
than 15 percent) along and north of I-64 on Friday and right now
will keep this going. Saturday looks dry in most of the ensemble
and deterministic guidance, but again some differences in the
guidance lead to some uncertainty on if this holds. The boundary
might be able to reactivate Sunday, with PWATs rising to 1.2 to
1.3 inches in the ensembles mean of the EPS/GEFS/GEPS. This would
only lead to a around a 20 percent chance of rain mainly south of
the Hal Rogers and Highway 80 region. The cluster analysis shows
most of the area will see generally less than a quarter of an inch
of rain through the period and seems reasonable given the lack of
better moisture return through the period, with PWATs running
around average or just below through the period.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
ISSUED AT 220 PM EDT SUN JUN 9 2024

A mixture of VFR and MVFR was in place across the region at
issuance time with some MVFR in the south ahead of a cold front
that has sagged south to near the Mtn Parkway. In addition to the
MVFR ceilings in places in the south, some showers and a couple of
storms have also developed or moved into areas near Lake
Cumberland and the VA border. This activity will move near KSME
and KLOZ over the first couple hours of the period and VCTS was
used there, though trends take the thunder just south of both
locations. After the convection to being the period in the south,
improvements to prevailing VFR are expected areawide by about 22Z
and there after VFR will largely prevail through the period as
the front settles to the south and high pressure noses into
eastern KY. A weakening secondary front that sags into the OH
Valley and eastern KY later tonight and across the area on Monday
should have little affect on the weather. River valley fog is
possible in the 04Z to 13Z timeframe, especially where any of the
convection occurs over the next few hours. However, this is not
expected to affect the TAF sites at this time. Winds will average
west and to northwest at generally 10 KT or less for the first 6
hours or so of the period, before becoming light and variable.

&&

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

$$

SHORT TERM...JP
LONG TERM...DJ
AVIATION...JP