908
FXUS63 KJKL 180539
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
139 AM EDT Tue Aug 18 2026

.KEY MESSAGES...

- Mainly dry weather returns Tuesday through Wednesday, before
  another cold front brings a return of thunderstorms Wednesday
  night or Thursday.

- Somewhat cooler and less humid weather is expected for the
  weekend.

&&

.UPDATE...
Issued at 752 PM EDT MON AUG 17 2026

What appear to be the back edge of this evening`s precip (actually
post frontal) is over our northwest counties. Have tried to time
this ending southeastward.

&&

.SHORT TERM...(This evening through Tuesday night)
Issued at 430 PM EDT MON AUG 17 2026

Late this afternoon a cold front is on the western edge of the
forecast area, progressing southeastward beneath west northwest
flow aloft. Instability ahead of the front varies across the
forecast area, with earlier clouds somewhat limiting heating in
our northern counties. Dew points are also higher in the south.
This is resulting in SPC mesoanalysis 100mb mixed layer CAPE near
3K J/Kg by the TN border, but only around 1.5K J/Kg in the north.
Shear is not impressive, but sfc-3 Km of 25-30 kts is enough to
pose a risk of svr wx in the higher instability, and SPC has a
watch for our southernmost counties. As wet as it is from recent
rains, a Flood Watch remains in place for most of the area.
However, the most intense storm potential in the far south
fortunately does not line up with where flooding rains occurred
yesterday.

The cold front will progress southeast out of the forecast area
this evening, and our threat of significant wx will end. Much
drier air will move in aloft, but only modestly drier in the
lowest levels. With rather weak surface flow, it`s a setup for
fog. Have hit it rather hard in the forecast, and the situation
will need to be watched for the need of a SPS or for advisory
later tonight.

Drier air continues to arrive in the lower levels on Tuesday, but
soundings show enough destabilization first to possibly give some
light showers around mid day in our southeast. However, the
atmosphere looks capped to deep convection and thunder. Any
showers dry up by evening and mainly clear skies are then expected
through the night. The drier air mass should allow for lows in
the low-mid 60s y dawn on Wednesday-- cooler than we`ve seen for
a while.

.LONG TERM...(Wednesday through Monday)
Issued at 444 PM EDT MON AUG 17 2026

The long-term period will begin Wednesday, with more zonal flow
aloft across the Ohio Valley, but changes are on the horizon.
This comes as an upper-level ridge amplifies out in the western
CONUS while the eastern CONUS trough digs southward.
Wednesday looks to stay largely dry across eastern Kentucky, as a
cold front slowly works southward across the Ohio Valley.
However, by Wednesday night this boundary will sag closer to the
area and shortwaves riding through the broader flow will aid in
forcing convection. This will lead to an increasing threat of
showers and thunderstorms Wednesday night, with chances peaking in
the 40 to 50 percent range mainly north of I-64 and lesser chances
toward the Virginia border. The chance of showers and thunderstorms
then increases further Thursday, as the frontal boundary sags deeper
into Kentucky and a more pronounced shortwave arrives. There is a
decent surge of moisture noted with the boundary, with PWAT values
generally in the 1.5 to 1.75 inch range, but the overall movement of
this activity is expected to be more progressive. Even so, if you
can get multiple rounds of convection we could see at least some
minor flooding issues, and WPC does have us in a Marginal Risk (1
out of 5) for Thursday into Thursday night. There is at least
some question on the potential for a few stronger storms, with
MUCAPE in the 1000-2000 J/kg range and effective shear in the
30-40 kt range. This is a reasonable enough parameter space to
aid in organizing convection, with the main risk being strong wind
gusts. This comes as DCAPE values rise to around 1000 J/kg
Thursday afternoon. By the end of the week, this boundary is
expected to slowly sink southward. There is some uncertainty as to
how far, but enough to keep rain chances lower for Friday and
Saturday, generally in the chance range. Then by the late weekend
into early next week there remains at least some model uncertainty
with regard to the depth of the eastern CONUS trough. Some
guidance shows a cutoff upper low developing further south across
the northern Ohio Valley, which could certainly lead to more
widespread shower and thunderstorm activity if realized
especially on Sunday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
ISSUED AT 139 AM EDT TUE AUG 18 2026

A cold front is sagging southeast of the area early this morning.
In its wake, a mixture of low stratus and fog is expected to
develop in a weak northwest upslope flow regime, leading to the
development of MVFR or worse conditions through daybreak. The low
stratus and fog will gradually lift after sunrise and scatter out
into a cumulus field during the afternoon. Winds will be light
and variable through 12Z, then become northwest at less than 10
kts by late morning.

&&

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

&&

$$

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