978
FXUS63 KJKL 011901
AFDJKL

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

.KEY MESSAGES...

- Pleasant and mostly dry weather is expected to continue through
  Labor Day, with only a small chance of showers or thunderstorms
  this afternoon, mainly over southern Kentucky.

- Showers and thunderstorms are possible area wide Tuesday, with
  higher probabilities for Wednesday and Thursday ahead of an
  approaching cold front.

- Rainfall totals through Thursday are expected to be around an
  inch or less for most locations.

- Below normal temperatures are expected through the period, with
  the coolest conditions mid to late week behind the relatively
  strong cold front.

&&

.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...(Tuesday night through Sunday)
Issued at 434 AM EDT MON SEP 1 2025

The start of the long-term period features the remnant of Tuesdays
shortwave. In addition to this disturbance, an even stronger trough
is forecast to develop and track southeastward toward the
Commonwealth. Throughout the day Wednesday, the first disturbance
will bring increased PoP to the forecast area, but as the second
trough tracks southeast, a surface cold front will approach the
region. Showers and storms will accompany both features and will
persist through the day Wednesday into Thursday before FROPA occurs
late Thursday afternoon.

The upper-level trough and its closed circulation will remain
persistent over the Great Lakes, and another perturbation will track
through the mean flow, bringing another system through the Upper
Midwest and Great Lakes. As the two systems Fujiwhara around each
other, another round of showers and storms is expected for Friday
into Saturday before the associated cold front moves through the
area on Saturday morning. A surface high-pressure system will build
into the region behind the exiting cold front, bringing below-
average temperatures and much more fall-like weather for the
remainder of the forecast period.

The period will be marked by multiple upper-level disturbances that
will bring increasing shower and thunderstorm activity from
Wednesday through early Saturday morning. Several fronts will move
through the region, the first late Wednesday night and again late
Friday night. Temperatures will remain nearly seasonal, with highs
in the mid to upper 70s and overnight lows in the upper 40s to mid-
50s. Behind the final front, below-average temperatures and dry
weather will build into the region for the weekend.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
ISSUED AT 220 PM EDT Mon Sep 1 2025

VFR conditions are generally expected to prevail through the TAF
period, though with some notable exceptions. Scattered showers and
thunderstorms are forecast to impact the Lake Cumberland and I-75
corridor areas this afternoon/evening and could lead to brief
reductions in category at KSME and KLOZ, thus warranting a PROB30
at both. Additionally, fog is expected to develop in the favored
river valleys and also at locations that experience rainfall later
this afternoon into this evening. It is possible that this fog
could impact KSME and KLOZ, hence the mention of MVFR in the TAF
late tonight; however, overall confidence in its occurrence is
only moderate. Lastly, winds will be light and variable outside of
convection.

&&

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

&&

$$

SHORT TERM...GEERTSON
LONG TERM...VORST
AVIATION...GEERTSON