682
FXUS63 KJKL 200550
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
150 AM EDT Thu Aug 20 2026

.KEY MESSAGES...

- 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 1155 PM EDT WED AUG 19 2026

No significant changes were made to the forecast with mainly just
the inclusion of the latest obs and trends for the T/Td/Sky grids.
The PoPs and weather grids represent the latest thoughts on the
evolution and impacts of the developing MCS to the west. These
adjustments have been sent to the NDFD and web servers along with
a freshening of the SAFs and zones.

UPDATE Issued at 720 PM EDT WED AUG 19 2026

23Z sfc analysis shows that the weak high pressure in place over
the state has been worn down even further during these past 24
hours. This entails some mid level clouds and light showers
dissipating through the northern parts of the CWA this evening.
We remain south of the main front residing west to east over the
northern Ohio Valley while an area of low pressure over southern
Missouri moves this way. Currently, temperatures vary from the
upper 70s for most of the northern parts of the area - owing to
the clouds and showers that lingered there - and the lower 80s in
the sunnier south. Meanwhile, amid light southerly winds of up to
5 mph, dewpoints are generally in the upper 60s to lower 70s.
Have updated the forecast mainly to add in the latest obs and
trends for the T/Td/Sky grids but also to incorporate the current
CAMs thoughts on the dying MCS that is progged to slip into the
area well after midnight. These minor adjustments have been sent
to the NDFD and web servers along with a freshening of the SAFs
and zones.

&&

.SHORT TERM...(tonight through Thursday night)
Issued at 413 PM EDT WED AUG 19 2026

There is a messy wx map late this afternoon, with one frontal
boundary stalled across the Deep South, and another one to our
north over the Midwest. The southern boundary is relatively quiet
at this point, while the northern one has thunderstorms developing
near it. Mesoscale models are suggesting an MCS will develop over
southern MO this evening as warm/moist air overrides the southern
boundary. It then propagates eastward during the night, with its
remnants reaching us overnight and early Thursday as it weakens.
The northern convection may also slowly drop south tonight. As has
been the case in recent weeks, there is not a lot of confidence
in exactly how it all plays out. A blend of the latest model runs
still suggests likely POPs making it into our area from the west
early Thursday, but this is a drop from the previous forecast
cycle. Clouds lingering during the day Thursday will cut into
destabilization and probably limit the POP, even though the
northern boundary should slowly sink south into the area as a cold
front. A shortwave trough should approach from the northwest
Thursday night as the front gets ready to drop south of the area.
Models generate convection with this, especially for our southern
counties. Without a lot of confidence, the POP is held below the
likely threshold at this point, but that could change if there is
continuity in the models in future runs.

.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 06Z TAFS through 06Z Thursday night)
ISSUED AT 150 AM EDT THU AUG 20 2026

VFR conditions prevailed at the TAF sites at 06Z. Valley fog has
also developed along many of the mainstem rivers but is not
expected to reach the terminals. Instead, an MCS presently over
the Mid-Mississippi Valley is expected to press eastward and
eventually impact all terminals for a few hours between 10 and
16Z. The precipitation is likely to bring a period of sub-VFR
flight categories. After a lull, additional - more scattered -
storms may develop across the area into the afternoon and evening.
Winds, away from any storm, will be light and variable early this
morning, becoming southwest around 5 kts during the daylight
hours.

&&

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

&&

$$

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