573
FXUS63 KJKL 040535
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
135 AM EDT Thu Sep 4 2025

.KEY MESSAGES...

- Multiple rounds of showers and thunderstorms are likely to
  impact the area between now and Saturday, with the highest
  probabilities immediately ahead of approaching cold fronts
  Thursday afternoon and Friday evening.

- A few of the storms Thursday afternoon may be strong to severe;
  damaging wind gusts are the primary concern.

- Widespread rainfall totals between 1.0 to 1.75 inches are
  possible through late Saturday night, but locally higher totals
  are possible wherever stronger convection occurs.

- Below normal temperatures and drier weather will return this
  weekend after the two frontal boundaries clear the area.

&&

.UPDATE...
Issued at 1053 PM EDT WED SEP 3 2025

Adjusted PoPs lower to remove mention from the forecast through
the early overnight, with increasing PoPs thereafter. Also updated
forecast hourly temperatures through the overnight using the
latest observed hourly temperature readings as the initialization.

UPDATE Issued at 733 PM EDT WED SEP 3 2025

Adjusted PoPs to match latest radar trends. Will have thunder
chances out of the CWA by 01z in the grids, though thunder chances
return toward morning with the advance of the cold front toward
the area. Tricky part of the forecast is with clearing this
evening the extent of fog formation across the area.

&&

.SHORT TERM...(This evening through Thursday night)
Issued at 420 PM EDT WED SEP 3 2025

Regional radar imagery shows widely scattered convection across
the forecast area at mid-afternoon. The bigger picture setup shows
the upper-level low responsible for the cooler and unsettled
weather of late now almost fully absorbed by a digging trough (and
a much deeper embedded ~546 dam closed low now centered
immediately north of Lake Superior). Multiple disturbances are
rotating around the parent low within the larger trough; one is
currently exiting the area, while a second approaches from the
Lower Ohio River Valley, followed by a third further upstream
between Chicago and Kansas City. Behind that, a more substantial
vorticity lobe and surface cold front are diving southeast from
the Upper Midwest. Most of the ongoing convection of the JKL CWA
is associated with the second disturbance. There is sufficient
instability with the SPC Mesoscale analysis indicating 500 to 1000
J/kg of MLCAPE across most of the area. Moisture is at seasonable
levels, with PWATs in the 1.1 to 1.2 inch range, and temperatures
are likewise mild for early September, ranging from the upper 70s
to lower 80s in locations not recently impacted by substantial
rainfall or cloud cover.

The aforementioned strong upper-low continues to deepen to ~540
dam while pinwheeling southeast across Lake Superior this evening.
This low continues to deepen overnight and during the day on
Thursday but will actually pivot back to the north and further
deepen to around ~527 dam by daybreak Friday, spinning to just
west of James Bay. The ongoing convection should slowly diminish
this evening with the loss of surface-based instability, though
there will still be the possibility of a stray shower or storm
through the overnight with increasing low-level warm air and
moisture advection ahead of the approaching front. Toward morning
(most likely after 4 AM EST), the next surface trough arrives on
our northwestern doorstep, most likely attended by a decaying
squall line. While severe storms are not expected with the line,
winds could still be strong and gusty (20 to 40 mph) as the line
passes. The big question on Thursday becomes how much
destabilization is able to occur as that squall line stalls and
dissipates over our area. At the present time, forcing for the
squall line appears more meager with southern extent and thus
locations closer to the Tennessee border are favored to see less
rainfall/cloud cover and a quicker return of sunshine heading into
the afternoon hours ahead of the cold front. If sufficient
instability does develop, increasing shear of 30 to 35 knots could
support a few transient supercell structures. The primary hazards
with any stronger storms would be small hail and damaging wind
gusts. On the rainfall side, most areas can expect 1/2 to 1 inch
of rainfall. However, localized amounts exceeding 2 inches could
occur where storms are most persistent. Given the still dry
conditions in many areas, widespread high water issues are not a
concern. However, those isolated locations that have received
multiple inches of rainfall in recent days and now have nearly
saturated soils might have minor flood issues if they are affected
again by the most persistent thunderstorm activity. Convection
should wane Thursday evening with the boundary stalling over our
area as it is abandoned by its upper-level forcing.

In sensible terms, look for isolated to scattered garden-variety
showers and thunderstorms to diminish this evening with the loss
of daytime heating. Otherwise, it will be variably cloudy with
some fog in the deeper sheltered valleys and low temperatures in
the upper 50s to lower 60s. Toward sunrise on Thursday morning,
anticipate gusty showers and possible thunderstorms sweeping in
from the northwest with clouds and showery conditions lingering
for much of the morning. There is potential for some clearing
heading into the afternoon ahead of another line of showers and
thunderstorms, but that is less certain, especially northeast of
US-25. If strong storms develop, the primary threat appears to be
damaging wind gusts and small hail. It will be cooler with high
temperatures only in the mid 70s north to around 80 near the
Tennessee border. Showers and storms diminish again Thursday
evening with mainly low clouds lingering overnight. Low
temperatures are forecast to range from the mid 50s along the I-64
corridor to the lower 60s near the Virginia border.

.LONG TERM...(Friday through Wednesday)
Issued at 250 PM EDT WED SEP 3 2025

A 990mb surface low will continue to churn over Ontario on
Friday, placing the majority of eastern CONUS in a troughing
pattern. By late Friday morning, a shortwave will form near the
Great Lakes Region and follow the outer periphery of the
aforementioned low. This disturbance will eject a cold front
towards eastern Kentucky, providing another area of focus for
shower and thunderstorm development.

Friday afternoon temperatures will be quite warm: in the mid to
upper 80s. Ample SBCAPE will exist, especially in southeast KY
where ensemble probabilities place a greater than 60 percent
chance of SBCAPE exceeding 1000 J/kg. Low level lapse rates will
be relatively strong, but upscale storm growth will be hampered by
lack luster midlevel lapse rates. A few severe storms may form
late Friday afternoon / evening with the primary threat being
damaging winds. Luckily, the window for severe storms will be
brief as the environment becomes less favorable after sunset. Rain
will persist overnight with FROPA eventually occurring Saturday
morning.

A much cooler and drier forecast exists for the remainder of the
weekend as high pressure settles into the region. Afternoon highs
will be in the upper 60s to mid 70s Saturday and Sunday. A slight
warming trend will be evident next week as upper level ridging
forms over eastern CONUS. By Wednesday, expect highs to be in the
upper 70s and lower 80s.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
ISSUED AT 135 AM EDT THU SEP 4 2025

VFR conditions are prevailing across all TAF sites with this
issuance. However, to the northwest, a cold frontal boundary is
diving southeast toward the area. Showers and thunderstorms will
accompany that boundary through the morning into the afternoon and
late evening. Reductions in category are expected with this front
and those reductions will vary throughout the day due to lowered
CIGS and reduced VSBY. Showers and storms will begin to taper off
toward 00Z/Friday but terminals are forecast to remain at least
MVFR through the remainder of the forecast period. Lastly, light
and variable winds will prevail but gusty and erratic winds will
accompany convection.

&&

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

&&

$$

UPDATE...CMC
SHORT TERM...GEERTSON
LONG TERM...SCHLESSIGER
AVIATION...VORST