879
FXUS63 KJKL 181941
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
341 PM EDT Tue Aug 18 2026

.KEY MESSAGES...

- Mainly dry and cooler weather returns through Wednesday, though
  locally dense river valley fog is expected late tonight.

- A cold front brings scattered to widespread thunderstorms
  Wednesday night 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 1122 AM EDT TUE AUG 18 2026

Hourly grids have been freshened up for recent observations and
trends. Some drizzle or sprinkles in upslope flow may linger from
the stratocu and cumulus as those this should be fleeting as
daytime heating and mixing progress into the afternoon.

&&

.SHORT TERM...(Today through Wednesday)
Issued at 400 AM EDT TUE AUG 18 2026

A cold front has finally settled south of the area early this
morning, bringing an end to the repeated daily torrential downpours.
It is still quite mild and muggy, though, as temperatures remain
mostly in the lower 70s with relative humidity values near 100%.
This moisture is manifesting as low stratus and fog in a weak but
still damp post-frontal northwesterly upslope flow. The moisture
is sufficiently deep for patchy drizzle or perhaps even some
sprinkles at times, especially along and east of the Pottsville
Escarpment. The latest surface analysis shows this northwesterly
flow is associated with anticyclonic flow around a ~1017 mb high
centered near St. Louis, MO. Farther upstream, a cold front
extends southwestward from a low near James Bay to over the
Northern Plains ahead of a digging 500 hPa trough.

That 500 hPa trough translates eastward and digs across the Great
Lakes, reaching its greatest depth on Wednesday morning, but only
glancing the Ohio Valley. As a result, the surface high pressure
will build eastward today, bringing drier air with it, cresting
over eastern Kentucky tonight, with PWATs bottoming out near 1.0
inch. The high pressure will then subside southward on Wednesday
as the upstream cold front approaches, yet slowing to a crawl as
it reaches the Lower Ohio River. In the southwesterly return flow
ahead of this boundary, PWATs over eastern Kentucky rise to
between 1.50 and 1.75 inches by the end of the day on Wednesday.
Showers and thunderstorms approach our Bluegrass counties late in
the day but are currently favored to not reach us until after the
end of the short-term period.

In sensible weather terms, a dreary mixture of fog, low stratus,
and/or drizzle this morning will gradually transition over to an
extensive cumulus field this afternoon. It will be cooler and
less humid than recent days, with high temperatures only in the
lower to middle 80s while dew points dip back into the 60s. For
tonight, mostly clear skies and light winds should allow for
extensive radiational fog formation in sheltered river valleys,
perhaps even growing deep enough to impact adjacent ridges. It
will be cooler, with lows in the lower to middle 60s. For
Wednesday, fog will mix out in the morning under mostly clear
skies, which will then give way to increasing mid-and high-level
cloud cover during the afternoon. Temperatures will rebound into
the mid to upper 80s by the afternoon.

.LONG TERM...(Thursday through Tuesday)
Issued at 330 PM EDT TUE AUG 18 2026

At the onset of the extended forecast period, large-scale 500 mb
troughing remains anchored across much of the eastern CONUS. In
the pre-dawn hours Thursday, a nocturnal 40-50 kt low-level jet
(LLJ) oriented across western and central Kentucky will coincide
with a shortwave passing through the Ohio Valley. While the LLJ
weakens to 30-40 kts as it shifts into eastern Kentucky, rounds of
showers and thunderstorms are expected through Thursday. The
first round will move through during the morning hours, favoring
areas across the Cumberland, Southern Licking, and Big Sandy River
basins near the TN, VA, and WV borders. A brief lull in activity
is expected before redevelopment occurs early Thursday afternoon
along the I-64 corridor, propagating south through the remainder
of the day. Models indicate drier air working in aloft by late
afternoon, which could suppress rain chances. However, the
environment will support PWAT values near 1.75 inches (80th to
85th percentile of climatology). Given saturated soils from recent
rainfall, isolated instances of minor flooding remain possible
Thursday through Thursday night, supporting WPCs Marginal Risk
(Level 1 of 4) for excessive rainfall. Adequate storm motion
should keep activity progressive, limiting widespread flash
flooding potential.

As the frontal boundary associated with Thursdays convection lingers
near the area on Friday, shower and thunderstorm chances will
persist, with the highest probabilities during the afternoon along
and south of the Hal Rogers Parkway / KY Highway 80 corridor.
Beyond Friday, models and ensemble guidance remain in broad
agreement on a continued upper-level pattern featuring a ridge
over the western CONUS and troughing across the east, though
amplitude differences remain. Another shortwave embedded within
the longwave trough is projected to dig out of the Upper Midwest
into the Great Lakes and Ohio Valley Saturday into Sunday.
Multiple 00Z AI-based guidance suites from August 18th show
conditional severe potential on Saturday, primarily centered over
SW Pennsylvania, with lower probabilities (5-15%) extending
southwest into eastern Kentucky. At present, PoPs support isolated
to scattered coverage across the Licking and Big Sandy basins on
Saturday. Isolated shower or storm activity may linger across the
Big Sandy early Sunday morning; otherwise, dry weather is expected
to return through Monday morning. By Monday afternoon, guidance
depicts another upper-level lowwhich a few models attempt to
close offdigging southeast from the Upper Midwest into the
Northern Great Lakes. This feature could bring another round of
shower and thunderstorm chances to the area on Tuesday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
ISSUED AT 155 PM EDT TUE AUG 18 2026

Cumulus was present across the region at issuance time with all
areas in or climbing into the VFR range with these as high
pressure builds into the OH Valley and ushers drier air. More
widespread fog is probable tonight compared to last night as that
high pressure system crests over eastern Kentucky. This fog should
bring reductions to MVFR initially as early as 04Z in some areas,
with some reductions to IFR or lower in many locations between 07Z
and 08Z and 12Z, before fog begins to lift and categories improve
in all areas by 13Z to 14Z. West northwest to northwest winds at
10KT or less are expected to begin the period, before becoming
light and variable by around 00Z. West to northwest winds at less
than 10KT should return to end the period along with the potential
for a few cumulus as well after about 15Z.

&&

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

&&

$$

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