JKL issues Area Forecast Discussion (AFD) at Sep 25, 5:30 AM EDT716
FXUS63 KJKL 250930
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
530 AM EDT Thu Sep 25 2025
.KEY MESSAGES...
- The threat for isolated flooding will continue into this
morning, especially where heavy rain persists.
- Widespread rain will taper to scattered showers by late morning.
A daily risk for isolated showers will then continue through the
weekend, mainly near the Virginia and Tennessee border.
&&
.SHORT TERM...(Today through Friday)
Issued at 342 AM EDT THU SEP 25 2025
While most of eastern Kentucky is currently experiencing a lull
in rainfall, regional radar mosaic shows a pronounced band of
rain with embedded convective elements extending from Southeast
Ohio to Middle Tennessee. The band is pivoting slowly
counterclockwise around a fulcrum point: a ~1008 mb surface low
centered near Cincinnati. The low is tracking along a wavy frontal
boundary extending from the Southern New England through the Mid-
Atlantic southwestward along the Ohio River and then further
southwest into Texas. Aloft, a positively-tilted trough axis
extends southwest from a parent low over northern Michigan to over
Texas. A 20 to 30 kt southwesterly flow at 850 mb continues to
feed a moisture-rich airmass (PWATs of 1.7 to 1.8 inches) into the
low's circulation, ascending into a 300 mb jet over Lake Erie.
This deep-layer moisture feed, along with a deep warm-cloud
layer, will continue to support efficient rainfall production.
Through the remainder of the morning, the concern for isolated
flooding remains, particularly if torrential downpours persist
over a given area. The threat is highest near and north of I-64,
where the band is pivoting more slowly. The upper-level trough
will slowly translate eastward through the day, with its
associated support steering the surface low with it. Consequently,
the steadier precipitation will taper from west-to-east between 8
AM and noon. With better forcing over the north, southern
portions of the precipitation band may tend to weaken or become
broken as it transits the area, keeping overall lighter rainfall
amounts in the south and heavier rainfall amounts in the north.
NBM favors closer to one-third of an inch over the southeast up to
1 inch north of I-64 through 18z, though this reflects the
general gradient and not the absolute max and min values
(additional amounts exceeding 2 inches cannot be ruled out at
isolated northern locales where heavy rainfall is most likely to
persist). Once the surface low pulls away, PWATs will decrease to
under 1.5 inches as the column dries aloft. There will still be
sufficient low-to mid-level moisture, however, for scattered
showers and perhaps some weak thunderstorms through the remainder
of the day, as upper-level perturbations eject from the trough
axis and interact with weak diurnal destabilization. Convective
vigor and depth will be limited by the meager CAPE profiles
(MLCAPE 400-800 J/kg per the RAP13), though ample shear will be
present (EBWD >30 kts). As daytime heating diminishes this evening,
convection will wane. Overnight, abundant low clouds and fog will
persist within a saturated, moist-adiabatic layer from the
surface to 800 mb as the wavy cold front seeps southeast.
Meanwhile, the upper-level trough will pull away to the northeast
while the southern portion of the trough shears off, with its
energy consolidating into a weak closed low near or over
Nashville, TN. Cyclonic flow around the low will combine with the
lingering shallow moisture to promote substantial cloud cover on
Friday but dry air and weak lapse rates in the mid-levels will
strongly limit convection depth and vigor.
In terms of sensible weather, expect showers and embedded
thunderstorms to develop from west to across eastern Kentucky
through sunrise before gradually tapering from the west through
the remainder of the morning. Rainfall amounts of one-third to 1
inch should be common, but locally higher amounts leading to high
water and flash flooding cannot be ruled out, especially near and
north of I-64. Scattered to numerous showers and thunderstorms
are then possible through the remainder of the day. It will be
mild with highs in the mid 70s. For tonight, expect extensive low
clouds and fog, with patchy light rain or drizzle possible, and
lows in the low to mid-60s. On Friday, expect a mix of sun and
clouds with a low chance of showers and thunderstorms southeast of
I-64; the highest chances will be near Middlesboro. It will again
be mild with highs in the mid 70s for most locations.
.LONG TERM...(Friday night through Wednesday)
Issued at 506 AM EDT THU SEP 25 2025
Though the weekend should tend to be drier overall, the lingering
upper-level low will tend to keep ample cloud cover as well as a
daily risk of isolated to widely scattered showers over portions
of the area, particularly closer to the Virginia and Tennessee
border. There is still significant uncertainty early to mid-week
with evolution of the upper-level low. The previous discussion
still covers the long-term pattern well.
Previous discussion issued at 235 PM EDT WED SEP 24 2025
For Friday, a positive upper trough axis will continue to move
slowly into the central and southern Appalachians with the frontal
boundary moving well southeast of the area. However, an inverted
surface trough will remain just south and east of the area.
Shear axis and associated Q-Vector forcing will keep chances of
showers especially areas near the KY/VA and KY/TN state-lines. CAPE
looks quite limited so thunder chances quite low.
For much of the extended period from Friday through at least Monday
the ensemble cluster analysis along with the latest deterministic
models are showing an upper trough axis being cut-off over the
Tennessee valley and central/southern Appalachians and weakening.
During this period, shear axis will rotate around this upper low
producing periods of better Q-Vector forcing and deformation zone
forcing. An inverted surface trough is also anticipated.
Ensemble CAPE probabilities do increase for Saturday, Sunday, and
Monday with afternoon values of 250-500 possible. This is likely due
to more sunshine in the afternoon hours. End result will be greater
coverage of diurnal showers and possibly thunderstorms. Threat
for strong to severe storms is quite limited. Greatest coverage
will likely remain near the KY/VA and KY/TN state-line.
For Tuesday and Wednesday, confidence is low on how this closed off
and weakening upper low will effect the area. Can not rule out a
slight chance of mainly diurnal convection.
Sky cover becomes less for late this weekend into early next week
which will allow for better radiational cooling conditions so will
modify the mins for the valley/ridge temperature differences.
Nighttime and morning fog will become more likely as well some dense.
&&
.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
ISSUED AT 200 AM EDT THU SEP 25 2025
At TAF issuance MVFR to VFR conditions were widespread south of
the Mountain Parkway where only isolated convection was occurring.
Further north, more widespread convection was leading to locally
IFR or worse conditions. Rain with embedded thunder will gradually
increase increase from west to east through the remainder of the
overnight as a low pressure center rides NE along the Ohio River.
The steadier precipitation will then taper to showers by late
Thursday morning but scattered showers and possible thunderstorms
will continue through the day. Activity will taper off Thursday
evening but little improvement in aviation conditions are expected
as fog and low clouds develop. Winds will be light tonight around
5 kts or less then gradually veer west to northwest during the day
on Thursday, generally at less than 10 kts.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...GEERTSON
LONG TERM...GEERTSON
AVIATION...GEERTSON
Source:
JKL issues Area Forecast Discussion (AFD) at Sep 25, 5:30 AM EDT---------------
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