681
FXUS63 KJKL 222355 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
755 PM EDT Fri Aug 22 2025

.KEY MESSAGES...

- A cold front will bring a potential for showers and
  thunderstorms this weekend, with the greatest probability in
  southeast Kentucky.

- A cool and dry air mass more typical of late September or early
  October will arrive by Monday and persist through the new work
  week.

&&

.UPDATE...
Issued at 740 PM EDT FRI AUG 22 2025

23Z sfc analysis shows high pressure over most of the Ohio Valley
with a lingering area of inverted low pressure in the southeast.
This is keeping the skies and convection mostly clear - but some
lingering threat remains in the far southeast for a stray shower
or storm. Currently, temperatures are running in the upper 70s
to the lower 80s. Meanwhile, amid light north winds, dewpoints
are generally in the mid to upper 60s. Have updated the forecast
mainly to add in the latest obs and trends for the T/Td/Sky grids.
Did also fine tune the PoPs through the night per the current
radar and CAMs guidance featuring small chances over the
Cumberland Valley into dawn Saturday. These minor adjustments have
been sent to the NDFD and web servers along with a freshening of
the zones and SAFs.

&&

.SHORT TERM...(This evening through Saturday night)
Issued at 343 PM EDT FRI AUG 22 2025

Fog and low clouds were slow to break up again today, but the
process was faster than yesterday. This allowed for more heating,
which has managed to fuel some shower and thunderstorm development
near the VA border. Will look for the precip to die out with loss
of heating/instability this evening.

Pattern changes then begin, leading to significant change in the
long term. A significant upper low along the Manitoba/Ontario
borer will slowly move east tonight through Saturday night, with
an associated trough expanding/deepening over the eastern CONUS.
As minor geopotential height falls begin by Saturday morning for
our area, would not completely rule out isolated precip again by
dawn, but the probability looks to low for inclusion in the
forecast at this point. As heating/destabilization occur on
Saturday with more height falls, will expected more development of
convective precip. The deepest moisture will be present over our
southeast counties, which will probably allow for the easiest
development and greatest coverage there. Activity is expected to
decline on Saturday night, but possibly at a slower pace due to
support from the amplifying upper level trough.

.LONG TERM...(Sunday through Friday)
Issued at 435 PM EDT FRI AUG 22 2025

The long-term period opens Sunday morning with a deep trough
dropping across the Eastern CONUS, associated with a nearly
vertically stacked ~550 dam low over James Bay. A surface cold
front extends southward from the low across the Eastern Great
Lakes and then southwestward along the western foothills of the
Central/Southern Appalachians. Behind this cold front, cool and
dry air is flooding southeastward from the Canadian prairies.

The cold front is progged to slowly drop southeast across the JKL
forecast area on Sunday. Locations near the Virginia-Kentucky
border will see the best opportunity for modest destabilization
prior to the fronts arrival. This will have a direct bearing on
overall rain chances. The highest PoPs, 50 to 60 percent, are
adjacent to Virginia but diminish to around 15 percent in the I-64
corridor. Once the boundary clears Eastern Kentucky, the cool and
dry Canadian air mass will flood in on a northwesterly breeze
during the evening, though it may relax a bit in deeper valleys
overnight. Dew points on Monday could drop into the 40s for most
locales by the afternoon while 850 mb temperatures settle to
between 10-11C. The chilly air will be maintained throughout the
day; in fact, a weak secondary cold frontal passage is possible on
Tuesday as a shortwave passes through the lingering troughing
aloft. Given the already dry air in place (PWATs of 0.5 to 0.75
inches), no rainfall is anticipated. However, LREF mean 850 mb
temperatures are forecast to sink further to between 8 and 10C. If
realized, these values would support daily maximum surface
temperatures of only 69 to 74 degrees below 1,500 feet ASL, and
even chillier temperatures over the higher terrain. This would be
10+ degrees below normal for the day. Shortwave ridging builds in
on Wednesday before heights start to fall again on Thursday-Friday
as additional vorticity energy rides through the lingering
troughing aloft. At the surface, this will be reflected by a high
pressure building and then later cresting over the Ohio Valley
late Wednesday. With the high center in close proximity, Wednesday
night may support the coldest temperatures we have seen since the
beginning of June. COOP MOS from the sheltered northern valleys
(e.g. West Liberty and Sandy Hook) suggests mid 40s as a real
possibility, though upper 40s to lower 50s are more likely at most
locations. The surface high will slowly shift off to the east
later in the week, allowing moisture and warmer temperatures to
filter back into the Commonwealth on a southerly flow.

In sensible terms, look for scattered to locally numerous showers
and thunderstorms on Sunday, with the best chances toward the
Virginia-Kentucky border and the lowest chances toward the I-64
corridor. It will still be warm with high temperatures expected to
be in the lower to mid 80s. A dry and cool stretch of weather
then ensues from Sunday night through the remainder of the new
work week with daytime highs mostly in the 70s and nighttime lows
in the mid 40s to mid 50s. The coolest time period appears to be
Tuesday through Thursday morning when nighttime temperatures for
many will drop to around 50 or lower while day highs will struggle
to surpass 75F in all but the warmest spots. Fog formation is
likely in the favored river valleys on most nights.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
ISSUED AT 755 PM EDT FRI AUG 22 2025

Conditions are VFR for all TAF sites at issuance. Any lingering
convection will die out this evening. Valley fog development is
expected late tonight, growing in breadth and depth and bringing
localized IFR or worse conditions for both visibility and CIGs.
Most TAF sites (the dewpoint depression for KSYM seems too large)
have a potential for impacts to varying extents. The fog and low
clouds will dissipate on Saturday morning, with conditions
reverting to VFR again area-wide. A small chance for a shower will
be noted in southwestern parts of the area Saturday afternoon, as
well. Winds will be generally from the north at 5 kts or less
through the period.

&&

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

&&

$$

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