908
FXUS63 KJKL 020205
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1005 PM EDT Mon Sep 1 2025

.KEY MESSAGES...

- Multiple rounds of showers and thunderstorms are likely across
  the area through Thursday, with the highest probabilities
  immediately ahead of a cold front on Thursday.

- Widespread rainfall totals between 0.5 to 1.0 inches will be
  highly beneficial given the antecedent dryness; locally higher
  totals up to 1.5 inches are possible in the Cumberland River
  basin, where drought is most prominent.

- Below normal temperatures are expected through the period, and
  the coolest low temperatures are forecast next weekend behind a
  secondary cold front.

&&

.UPDATE...
Issued at 1005 PM EDT MON SEP 1 2025

Have sent out more updates for a cluster of straggler storms over
and near Rockcastle County. Slow to die cells from the west and
east merged there, with new development in what would seem to be
one last spurt of very localized development this evening.

UPDATE Issued at 754 PM EDT MON SEP 1 2025

Only very isolated showers remain and are on the decline. Once
gone this evening, dry weather should last until at least near
dawn. Valley temperatures are again undergoing a rapid drop with
loss of insolation, and hourly forecast temperatures have been
adjusted.

&&

.SHORT TERM...(This evening through Tuesday night)
Issued at 301 PM EDT MON SEP 1 2025

A delightfully sunny and warm Labor Day afternoon is underway
across most of eastern Kentucky. The only exception is in those
counties adjacent to the Tennessee-Kentucky border where showers
and thunderstorms are ongoing. Temperatures are very comfortable,
ranging from the upper 70s to lower 80s for most, though they have
dropped closer to 70F at those locations recently impacted by
convection. The latest analysis shows that the weak inverted
surface trough, responsible for focusing the convection, resides
along the western slopes of the Appalachians from central
Mississippi northeastward into the Upper Ohio Valley. This feature
is lodged against a surface high pressure system that is firmly
in control of the weather from the Great Lakes eastward into New
England. Aloft, there is a weak and poorly defined 500 hPa low
circulation centered near/over West Virginia. A corridor of weak
instability is noted with the inverted trough, ranging from only
~100 J/kg of MLCAPE over the Big Sandy to between 500 and 1000
J/kg near Lake Cumberland. Precipitable water values are at
seasonable levels, but cell motions are slow, generally less than
10 kts.

Through the short-term period, the upper level low will drift
northward toward the Ottawa Valley as a northern stream trough
digs deeply into the Upper Midwest. At the surface, the high
pressure system will propagate southeastward to the eastern side
of the Appalachian Mountains while the inverted trough very slowly
pivots clockwise to become aligned more parallel to the Ohio
River. At the more local scale, guidance is suggesting that after
convection wanes this evening with the loss of daytime heating, a
surge of low-level WAA toward morning could cause a renewed threat
of isolated to widely scattered convection before and around
daybreak in the Lake Cumberland/I-75 corridor areas. As better
moisture becomes established over the CWA, MLCAPE values could
reach the 500 to 1500 J/kg range and support at least isolated to
widely scattered convection over the entire CWA during the
afternoon on Tuesday. Convection could persist into Tuesday night
as well, attending the passage of a 500 hPa shortwave trough and
vorticity maximum rotating through the still lingering troughiness
over the Ohio Valley.

In sensible terms, look for a pleasant Labor Day evening and
night for much of the area, though there will be a risk of
isolated to scattered showers and thunderstorms primarily for
locations southwest of KY-15. For tonight, expect variable
cloud cover, with fog developing in the favored river valleys and
in more sheltered spots impacted by recent rainfall. It will be
seasonably cool with temperatures falling back into the 50s for
most. On Tuesday, mostly to partly sunny skies will be the general
theme, but scattered shower and thunderstorm chances will be on
the rise, first in the vicinity of Lake Cumberland by daybreak and
then spreading northeast across the remainder of the forecast
area through the day. Temperatures should be similar or slightly
cooler than today with highs in the upper 70s for a majority of
the area, though some lower 80s are probable in the typically
warmest southern locales and also north of the Mountain Parkway.
Showers and a few thunderstorms may linger for a time into Tuesday
night. Variable cloud cover and areas of fog can be expected
otherwise. It will be seasonably mild with low temperatures
generally between 55 and 60F.

.LONG TERM...(Wednesday through Monday)
Issued at 503 PM EDT Mon Sep 1 2025

Much of the long term forecast period will feature an active, wet
weather pattern for Eastern Kentucky, but drier, fall-like
conditions are expected to return by next weekend. The synoptic
pattern aloft is dominated by a large upper level low pressure
spinning over the Great Lakes and related longwave troughing over
the eastern CONUS. As shortwave disturbances rotate around this
parent system, a couple of cold frontal boundaries and multiple
rounds of showers/storms are expected to cross the forecast area.

When the period opens on Wednesday morning, the first of these
perturbations will be passing through the Ohio River Valley, and
ongoing showery activity is likely to persist into Wednesday morning
as a result. Convective coverage should increase on Wednesday
afternoon as diurnal heating warms highs into the upper 70s/near 80,
but a second, stronger disturbance will approach the area from the
northwest overnight into Thursday. With better upper level support,
this second system will drag a cold front across the forecast area
on Thursday. Expect widespread shower/storm chances immediately
ahead of this frontal boundary on Thursday. While shear profiles
(LREF mean of 30 knots) look higher than what we have seen in
Eastern KY as of late, and moisture profiles look decent (PWATs will
likely approach 1.5 inches), surface-based instability will likely
be limited by ample antecedent cloud coverage. Thursday`s highs may
be relegated to the lower half of the 70s across much of the
forecast area, and this should limit the potential for stronger
convection. However, the frontal forcing, synoptics aloft, and a
seasonably moist airmass all point towards much-needed rainfall
across Eastern Kentucky on Thursday. Storm total QPF through
Thursday generally remains between 0.5 and 1.00 inches of rain,
with locally higher totals possible in the Cumberland River
basin. There, greater chances of convection in the short-term
forecast could lead to total accumulations up to 1.5 inches
across the entire forecast period. Probabilistic data reinforces
the notion that this rainfall will be beneficial rather than
hazardous; the LREF suggests that there is less than a 25% chance
of greater than 1.25 inches of rain in a 24 hour period this week.
Thus, flash flood guidance is unlikely to be reached during these
rounds of convection, and any rain that falls will work to
improve the D0 (Abnormally Dry) and D1 (Moderate Drought) drought
conditions currently in place across much of Eastern KY.

Behind the aforementioned frontal passage, skies will clear and
temperatures will cool. As winds diminish to diurnal minimums and
lows cool into the 50s/upper 40s, the wet grounds could lead to
patchy fog formation beyond just the typical sheltered valley
locations overnight on Friday morning. Any fog that does develop
overnight on Thursday should burn off quickly after sunrise, as
midlevel height rises associated with shortwave ridging point
towards a sunnier and warmer Friday afternoon, with highs near 80.

On Friday night into Saturday, yet another shortwave disturbance
will rotate around the upper level low and into the Upper
Midwest/Great Lakes. Model spread begins to increase around this
timeframe, but climatological pattern recognition points towards a
secondary cold front passing through the area to start the weekend.
Winds are expected to shift towards the northwest with this second
feature, and the airmass should be drier in the wake of the first
frontal passage. Thus, the greatest PoPs on Saturday will be in SE
KY, where NW flow typically leads to orographic lifting
enhancements. A few showers cannot be ruled out elsewhere, but the
most noticeable impacts with this secondary FROPA will likely be its
reinforcing shot of cool, dry air. Highs next weekend should stay in
the mid 70s, with overnight ridge/valley low temperature splits a
few degrees above/below 50 degrees. These cooler-than-average
temperatures and the clearer skies will give the sensible weather an
autumnal feel as we wrap up the first week of meteorological fall.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
ISSUED AT 702 PM EDT MON SEP 1 2025

Just prior to TAF issuance, isolated showers were ongoing over the
souther portion of the forecast area, but were on an overall
decline. They were likely bringing very localized sub-VFR
conditions, but they should die out early this evening and not be
a concern for TAF sites. Valley fog is forecast to develop again
late tonight and then dissipate early Tuesday morning. The highest
dew points and smallest dew point depressions are in the far
southern and southwestern portions of the forecast area early
this evening, including KSME. In consideration of that, KSME may
have some effects from it around dawn, but it should avoid the
other TAF sites. As heating occurs on Tuesday, scattered
showers/thunderstorms are forecast to develop, mainly over the
southwest portion of the forecast area (including KSME and KLOZ)
where dew points and instability will be greatest.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

UPDATE...HAL
SHORT TERM...GEERTSON
LONG TERM...MARCUS
AVIATION...HAL