JKL issues Area Forecast Discussion (AFD) at Sep 23, 8:21 PM EDT
881
FXUS63 KJKL 240021 AAA
AFDJKL
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
821 PM EDT Wed Sep 23 2026
.KEY MESSAGES...
- Showers and thunderstorms bring the risk of localized heavy rain
and flash flooding early this evening, and a Flood Watch
continues through 10 PM, mainly south of the Mountain Parkway
and east of I-75.
- Dry, cool weather settles in Thursday and last through early
next week.
&&
.UPDATE...
Issued at 735 PM EDT WED SEP 23 2026
23Z sfc analysis shows an inverted trough slowly exiting to the
east of the state. When combined with a passing shortwave trough
overhead, this is still capable of giving southeast parts of
Kentucky some excessive rainfall and flash flooding. Accordingly,
the Flood Watch continues through 10 pm with most activity
looking to fade to light showers after that point. Warming IR
cloud tops supports this idea, as well as the latest CAMs guidance
and now waning instability. Otherwise, temperatures are fairly
uniform across eastern Kentucky, generally in the mid 60s - along
with dewpoints - while winds are mainly from the north to
northeast at 10 mph or less. Have updated the forecast primarily
to extend the higher PoPs into the night in the far eastern parts
of the area per the latest radar loops and CAMs consensus
guidance. Did also add in the most recent obs and trends for the
T/Td/Sky grids. These adjustments have been sent to the NDFD and
web servers along with a freshening of the SAFs, FFA, and zones.
&&
.SHORT TERM...(This evening through Thursday night)
Issued at 517 PM EDT WED SEP 23 2026
A complicated scenario is in place late this afternoon. Sprawling,
very strong high pressure is centered over southern Quebec, and an
induced inverted/lee surface trough is along the western side of
the Appalachians in the flow around the high. The cooler air mass
has been making better progress down the eastern side of the
mountains, with remnants of our old (warmer, more moist) air mass
stuck here on the immediate western side. Meanwhile, an upper low
is approaching us from the northwest. Geopotential height falls
and cooling aloft with the approaching upper level low are
supporting convection which has become widespread in southeast
Kentucky. Movement has been slow and chaotic, with persistent
cells producing locally flooding rains.
Convection will persist into this evening, perhaps
moving/developing further northwest. As this happens, remaining
convection in our east will become more elevated above a
developing cold pool. As the upper low moves southeast over the
central Appalachians just to or northeast tonight, support will
wane and drying will progress into the JKL forecast area from the
west and begin to cut off precip. However, models suggest it may
linger into Thursday in our eastern counties before the upper low
finally cleanly departs to our southeast.
Clearing skies finally arrive thursday afternoon and evening.
This allows for radiational cooling on Thursday night. There will
still be a bit of a pressure gradient across the forecast area,
promoting northeast to east low level flow with cold air
advection. This will fight against decoupling. However, suspect
that at least the deeper valleys will decouple, which will allow
for the coolest temperatures we've seen in a while, below 50
degrees. Where decoupling occurs, valley fog is likely, especially
where the ground is wet from recent rain.
.LONG TERM...(Friday through Wednesday)
Issued at 249 PM EDT WED SEP 23 2026
Overall, the long term period will be characterized by cool and
quiet weather, owing to a fairly persistent midlevel ridge west of
the forecast area. At the start of the period, a vertically
stacked low will be located off of the North Carolina coast, with
a highly amplified ridge over the central CONUS. This low will
deepen as it lifts into the Northeast, blocking any eastward
progression of the ridge. Eastern Kentucky will find itself on the
western edge of northeastern troughing through at least the
weekend, with most guidance suggesting that this system will lift
far north into Canada by early next week. This will allow the
ridge axis to progress eastward, with the next major system not
approaching until the very end of the forecast period.
At the surface, this large scale pattern should keep weather cool
and dry through the weekend. Largely northeasterly winds around a
surface high over the Great Lakes will relegate dewpoints to the
40s, peaking in the mid 50s at their wettest. Even with mostly
clear skies each day, highs will range from the upper 60s to mid
70s. In short, it will finally feel less like summer and more like
fall. Overnight, clear skies and light winds will enable
efficient radiational cooling, with ridge valley splits expected
to develop. MOS guidance suggests temperatures will bottom out in
the low 40s in particularly sheltered valley locations on
Saturday, Sunday, and Monday mornings. Given that most guidance
agrees temperatures could fall into the mid 40s overnight (even
without considering terrain factors), this seems very feasible. It
may be time to get your jacket out.
By early next week, temperatures will warm somewhat as the ridge
expands eastward. Highs will climb into the low 80s in many
locations by Tuesday, although weather will still be dry. As of
now, the next rain chance looks to be Wednesday as a large scale
system approaches, but the details remain fuzzy this far out.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
ISSUED AT 820 PM EDT WED SEP 23 2026
Largely MVFR and IFR conditions were present to start the 00Z TAF
period. There was a large batch of showers and a few embedded
thunderstorms affecting locations generally southeast of the JKL
office. These poor conditions are expected to last for much of
the night, largely settling on IFR, along with showers at times
and a few stray thunderstorms into dawn. The overall precipitation
should taper off during the heart of the overnight, but and
sustained improvement in conditions is not expected until later in
the day, on Thursday. Away from any storms, winds will be
generally around 5 kts or less from the north to northeast through
the period.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
Flood Watch until 10 PM EDT this evening for KYZ069-080-085>088-
107>120.
&&
$$
UPDATE...GREIF
SHORT TERM...HAL
LONG TERM...FAGAN
AVIATION...HAL/GREIF
Source: JKL issues Area Forecast Discussion (AFD) at Sep 23, 8:21 PM EDT (https://mesonet.agron.iastate.edu/p.php?pid=202609240021-KJKL-FXUS63-AFDJKL-AAA)
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