571
FXUS63 KJKL 191828
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
228 PM EDT Wed Aug 19 2026

.KEY MESSAGES...

- Mainly dry weather through this evening, though locally dense
  river valley fog is expected early this morning.

- A cold front brings scattered to widespread thunderstorms
  tonight and Thursday, with a few strong wind gusts and
  localized heavy rain and flooding possible.

- Noticeably cooler and less humid air arrives this weekend and
  continues into early next week.

&&

.UPDATE...
Issued at 901 AM EDT WED AUG 19 2026

Based on satellite obs, have updated the very near term for fog
and low clouds holding on longer this morning in southeast KY.

&&

.SHORT TERM...(Today through Thursday)
Issued at 409 AM EDT WED AUG 19 2026

A quiescent morning is underway across eastern Kentucky with fair
skies as surface high pressure crests over the central and
southern Appalachians. Thermometers range through the 60s, or
about 5 to 10 degrees cooler than this time yesterday--the coolest
that much of the area has seen in 2 weeks or more. Nighttime
Microphysics satellite imagery shows tendrils of fog weaving
through the deeper river valleys, growing thicker with time.
Looking aloft, a 500 hPa trough is situated over the Great Lakes.
Under this trough, a cold front extends from an ~1001 mb low over
Hudson Bay south to Lake Huron and then southwestward into
Iowa/Nebraska.

Through the short-term period, pockets of vorticity energy will
ride through the flow aloft carving out modest upper-level
troughing across the Ohio Valley. At the surface, this will
result in the aforementioned cold front sinking southward while
subtle waves of low pressure ride along it. Guidance is in fair
agreement showing the front reaching the Ohio River by ~12Z
Thursday and then slowly sagging into the Commonwealth, though
its farther southward progress will be very slow with little
upper-level support. PWATs of 1.0 to 1.2 inches this morning will
rebound in return flow to between 1.75 and 2.00 inches by late
tonight as the front approaches. This will result in a gradual
increase in cloud cover through the daylight hours.

While there are multiple clusters of convection upstream, the first
cluster, now over Missouri, is projected to dive southeast and
dissipate as it runs out of instability. Behind that, the return
of better moisture and instability develops out of the Mid-South.
RAP/HREF guidance supports the convective cluster now over South
Dakota diving southeast, with it or a descendant MCS approaching
the Commonwealth late tonight, entering a moderate instability
(1500 to 2500 J/kg of MUCAPE) and shear (35 to 45 kts of EBWD)
environment over the Mid-Mississippi Valley. As that MCS
progresses toward the eastern Kentucky Coalfields after 06Z
Thursday, it will move into a less favorable environment with much
weaker instability, leading to a gradual overall weakening trend.
However, HREF probabilities still support at least a 10% chance
of sustained winds greater than 30 kts (gusts likely higher)
within 25 miles of a point west of an imaginary line from Mount
Sterling to Irvine to London, suggestive of a risk for isolated
damaging wind gusts. This is closely mirrored by a Marginal Risk
(1/5) of severe weather noted in the SPC Day 1 Convective Outlook.

Convective coverage and intensity for most of the day on Thursday
will be dependent upon how quickly we are able to clear out behind
the MCS. So far, CAMs suggest modest post-MCS destabilization and
rather sparse convective initiation, which makes sense given only
weak upper-level forcing, slackening shear as winds weaken aloft,
and a possible weak capping layer between 850 and 700 hPa.
Another upper-level perturbation does approach late in the day,
weakening the capping and making convective initiation more
probable as we transition into the long-term period Thursday
evening. Overall late-day rain chances are highest over southern
and southeastern Kentucky, as the cold front will likely already
be working across or south of the I-64 corridor. The parameter
space would support torrential rainfall rates with any stronger
storms on Thursday, but again coverage is uncertain. WPC has
maintained a Marginal Risk ERO (1/4), indicative of the possibility
for isolated high-water issues.

In sensible weather terms, look for fog to lift and dissipate this
morning, giving way to mostly sunny skies. High clouds will
increasingly filter the sunshine as the day passes while a few
fair-weather cu could bubble up as well. It will be seasonably
warm with highs in the mid to upper 80s. For tonight, temperatures
fall back into the mid 60s to near 70F, with showers and thunderstorms
arriving from the west after midnight. Some of the storms could
be on the strong side, especially near and west of I-75. Looking
ahead to Thursday, most of the day is presently favored to be dry,
though hit-and-miss storms cannot be ruled out, especially south
of the Mountain Parkway late in the day. It will again be
seasonably warm with highs in the lower to mid 80s.

.LONG TERM...(Friday through Wednesday)
Issued at 228 PM EDT WED AUG 19 2026

Some showers and storms will be possible at the start of the
extended period ahead of a sagging cold front. The primary
corridor for pre-frontal convection will initially reside along
and south of the Hal Rogers Parkway/KY-80 corridor toward the
Tennessee border. Aloft, the broad pattern features a ridge over
the western CONUS and a trough over the eastern CONUS. With broad
troughing modeled over the Great Lakes/Northeast and a distinct
shortwave axis extending south- southwestward through OH/IN/KY,
mid-level forcing will lag behind the surface boundary. This
lingering PVA combined with steepening mid-level lapse rates may
support isolated to scattered post-frontal convection Friday
afternoon, with the greatest chances remaining east of the
Pottsville Escarpment. Given weak ambient shear, any activity that
develops should remain pulse-like. While PWATs remain elevated
between 1.3 and 1.6 inches (50th to 75th percentile) into Friday
evening, significant mid-level drying will filter in from the
northwest, as reflected by modeled 700 mb RH dropping into the
teens. Clearing skies, calm winds, and strong subsidence/capping
under high pressure will favor areas of fog overnight Friday,
particularly within the river valleys.

An embedded shortwave within the longwave trough is modeled to
dig out of northwestern Canada into the Great Lakes and Ohio
Valley over the weekend. A reinforcing cold front will cross
Kentucky, though timing discrepancies maintain uncertainty in
POPs. Regardless, precipitation chances should remain isolated,
with the highest potential staying northeast of the forecast area.

High pressure briefly builds across eastern Kentucky early next
week, ushering in a cooler and drier airmass. Dew points lowering
into the upper 50s and lower 60s will be a welcome relief from
recent values in the upper 60s to lower 70s. Dry weather persists
through Tuesday before another shortwave propagates out of the
Upper Midwest into the region mid-week, bringing isolated to
scattered shower and thunderstorm chances back to the forecast.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
ISSUED AT 215 PM EDT WED AUG 19 2026

VFR conditions prevailed at TAF issuance and will last well into
tonight. Showers will be possible overnight into Thursday morning,
and a few thunderstorms can`t be ruled out. Valley fog may also
develop during the same time frame if clouds aren`t too extensive.
The precip or fog would bring sub-FVR conditions. During the mid-
late morning timeframe, an MVFR ceiling is also a possibility.

&&

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

&&

$$

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