742
FXUS63 KJKL 180826
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
426 AM EDT Fri Sep 18 2026

.KEY MESSAGES...

- Well-above normal temperatures persist into the weekend, with
  near-record heat possible over the Cumberland River Basin today.

- The heat, humidity, and a nearby frontal boundary could foster
  isolated to scattered thunderstorms across the area at various
  times over the next several days.

- Rain chances increase early next week as the persistent upper
  level ridging breaks down.

&&

.SHORT TERM...(Today through Saturday)
Issued at 426 AM EDT FRI SEP 18 2026

Unseasonably warm temperatures are noted across eastern Kentucky
this morning with readings ranging through the upper 60s to lower
70s. Skies are generally clear, though some fog is noted in
typical sheltered river valleys. Surface weather analysis shows weak,
amorphous high pressure over the Tennessee Valley, while a cold
front is draped from coastal New England to along the lower Ohio
River and westward into the central Plains. Translating aloft, an
~597 dam upper-level high is centered over northeast Texas. This
leaves Kentucky under northwesterly flow on the northeastern
periphery of the high.

The upper-level high will slowly weaken through the short-term
period, resulting in gradual height falls over the Commonwealth as
multiple weak perturbations ride around the high. At the surface,
the frontal boundary to our north this morning will consequently
sag southward into eastern Kentucky today, stall over the forecast
area tonight, and perhaps waver back to the north on Saturday. At
least isolated to scattered convection is expected to spark along
the southward-sagging cold front today, reaching locations north
of the Mountain Parkway between daybreak and midday and generally
sagging south-southwest with time. Shear will be minimal,
instability levels moderate, and the atmospheric profile very
moist (near climatological maximums for PWATs), favoring mainly
pulse-type, garden-variety convection. On Saturday, stronger MLCAPE
levels approaching 3000 J/kg and a slightly more notable dry
layer around 700 hPa could support stronger water-loaded updrafts
and subsequent downbursts--perhaps generating isolated wind gusts
approaching severe limits. Accordingly, SPC has placed a Marginal
Risk (1/5) of severe thunderstorms across the western half to
two-thirds of the JKL CWA.

In sensible weather terms, anticipate mostly to partly sunny skies
today once any valley fog burns off. Isolated to scattered
showers and thunderstorms are expected to reach northeastern
Kentucky after daybreak, with rain chances gradually dropping
south and west through the day, reaching the Lake Cumberland area
late afternoon or early evening. It will still be quite hot,
though not quite as warm as yesterday--expect highs mainly in the
mid 80s over the northeastern hills to the lower 90s over the
Cumberland River Basin. For tonight, showers dissipate, leaving
behind partly to mostly cloudy skies and renewed fog formation
through the river valleys. It will be mild, with lows in the mid
60s to around 70F. Looking ahead to Saturday, it will again be
partly to mostly sunny with a renewed threat of showers and
thunderstorms, especially during the afternoon and evening, with
high temperatures a degree or two cooler than today.

.LONG TERM...(Saturday night through Thursday)
Issued at 239 AM EDT FRI SEP 18 2026

Upper level ridging over the southeast CONUS will continue weaken as
we move into the the long term period. Largely zonal flow aloft will
be positioned just to our north at the start of the period. Multiple
weak impulses moving through the flow will help to drive it very
slowly southward as the upper high breaks down. By midweek, some
semblance of an upper low is forecast to evolve near the Great
Lakes, pushing faster flow aloft even further south for late week.

At the surface, this will eventually drive a significant cold front
southward. This boundary should start the long term period to our
north, near the Ohio River or further north, with its true position
possibly somewhat muddled by prior convection. There is potential
for some of this convection to feed off of our heat and humidity on
this side of the front and make it south into our area in the
Saturday night through Monday time frame, but confidence in details
is very low due to mesoscale influences which would be in play. The
greatest POP looks to be as the front pushes through. Models have
not come into agreement yet, with cold fropa timing likely to be in
the Tue-Wed time frame.

Noticeably cooler air should arrive behind the front as sprawling
surface high pressure sets up in the vicinity of the Great Lakes and
southeast Canada for late week. Our POP drops off with the change in
air mass, but some light precip won`t be completely ruled out,
depending on the evolution of the persistent upper low/trough and
any impulses rotating around it.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
ISSUED AT 153 AM EDT FRI SEP 18 2026

VFR conditions were observed over the TAF sites at the 06Z
issuance. Valley fog is likely overnight but impacts at the TAF
sites outside of KSME appear unlikely. Any fog should dissipate
rapidly after sunrise. Showers are then possible as early as
12-15Z across northeastern TAF sites such as KSYM, KIOB, and KSJS
ahead of a weakening cold front pushing south out of the Ohio
Valley. Thunderstorm chances pick up around 18Z at all terminals
except KLOZ and KSME, where chances begin more toward 20-22Z,
later tapering off after sunset. Showers and storms could lead to
MVFR or lower reductions and PROB30s have been included in the
TAF sites during the periods of greatest concern. Winds will
remain light and variable through daybreak before increasing to
around 5 kts from the northwest to northeast. Locally stronger
and erratic winds are possible near convection.

&&

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

&&

$$

SHORT TERM...GEERTSON
LONG TERM...HAL
AVIATION...GEERTSON/GINNICK