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261
FXUS63 KJKL 091847
AFDJKL

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

.KEY MESSAGES...

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- Shower and thunderstorm chances decrease through this evening.

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

.UPDATE...
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Issued at 200 PM EDT SUN JUN 9 2024

Hourly pops were updated based on radar and satellite trends with
convection having moved into portions of the Cumberland Valley
near Lake Cumberland while additional convection has developed
near the VA border. For now have the highest pops from the Lake
Cumberland region to near Black Mountain where the limited
instability and moderate shear combination is best ahead of the
cold front sagging south across eastern KY. At this point this
boundary is near the Mountain Parkway, but will continue south to
the TN and VA border into the early evening.

UPDATE Issued at 1152 AM EDT SUN JUN 9 2024

A cold front is gradually sagging south of the OH River and into
northern portions of eastern KY. Radar and satellite indicated
that the front is near the Interstate 64 corridor and gradually
slipping south of the interstate. Convection is occurring over
portions of western into Central KY while some recent shower
development has occurred near Lake Cumberland where cumulus is a
bit more agitated ahead of the front. Recent CAM runs have not
handled the convection that is working into central KY all that
well. The greater instability is forecast to reside southwest and
south of the area, with areas nearer to the TN border should have
MLCAPE climb to around 500 J/kg or slightly higher with effective
shear reaching 30 to 40KT. This could support some organized
convection near the TN border and points south and for a time in
the afternoon and the track and evolution of convection nearing
the I 65 corridor and Bowling Green area will be monitored for
possible further refinement of pops. For now areas near and north
of the Mtn Parkway will have drier air arriving as the front slips
south this afternoon so pops were lowered there. There remains
uncertainty on how far south the gradient will need to be though
areas right along the TN border will have the best chance for
thunderstorms.

UPDATE Issued at 735 AM EDT SUN JUN 9 2024

No big changes to the forecast with just the inclusion of the
latest obs and trends for the T/Td/Sky grids with this update
along with a tweaking of the near term PoPs per the latest radar
images. These minor adjustments have been sent to the NDFD and
web servers.
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&&

.SHORT TERM...
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(Today through Monday)
Issued at 455 AM EDT SUN JUN 9 2024

08Z sfc analysis shows high pressure now off to the east of
Kentucky while an area of low pressure is passing off to the
northeast. A cold front from this is starting to settle south into
Kentucky from the north. At the same time, ahead of this
boundary, a healthy cluster of storms is moving into central
Tennessee with its northern fringe riding east through south
central Kentucky. Thicker clouds have now spread into eastern
Kentucky ahead of those southern storms. These clouds kept
temperatures more uniform across the area early this morning after
we saw a bit more terrain based drop off during the evening.
Specifically, readings are generally from the mid 60s to lower
70s. Meanwhile, amid mostly light winds, dewpoints are in the
upper 50s to lower and mid 60s. The clouds also have kept most of
any fog at bay through the night.

The models, and their individual ensemble suites, remain in good
agreement aloft through the short term portion of the forecast.
They all depict a large 5h low north-northeast of Kentucky
dropping through the Ohio Valley and thereby tightening up the
northwest mid level flow over the region. Within this flow, an
impulse runs through the Tennessee Valley today while a more
substantial one pushes south from the Ohio Valley. This latter one
brings height falls and keeps more robust packets of energy
moving through the JKL CWA into Monday before the 5h trough axis
crosses this part of the state by that evening. The model spread
continues to be small enough that the NBM was used as the starting
point for the short term grids along with the incorporation of
the CAMs` details for PoPs today.

Sensible weather features a decent chance for showers and a few
thunderstorms through the area today, though the highest
probabilities for both will be found for the southern half of
eastern Kentucky. The southward movement of the cold front will
bring an end to the precipitation threat from north to south
through the JKL CWA during the afternoon. Only a small sliver of
southeast Kentucky will see a chance for showers after 00Z Monday.
Drier air, post frontal, will mean more in the way of ridge to
valley temperature differences tonight along with a potential for
fog in the valleys and places that manage to see the better rain
today. For Monday, we will stay dry even though 5h heights will be
falling as the northeast trough bottoms out nearby with ample
energy flowing above. This will make for rather cloudy skies and
cooler than normal afternoon temperatures to start the work week.

The main changes to the NBM starting point consisted of adjusting
the NBM PoPs to include CAMs details for the shower and storm
chances through the day. The temperatures from the NBM were
tweaked tonight in order to represent better terrain detail in a
drying wx regime.

.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.
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&&

.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.
&&

$$

UPDATE...JP
SHORT TERM...GREIF
LONG TERM...DJ
AVIATION...JP