758
FXUS63 KJKL 240145 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
945 PM EDT Sat Aug 23 2025

.KEY MESSAGES...

- A cold front will bring a potential for showers and
  thunderstorms to most of the forecast area through Sunday, 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 945 PM EDT SAT AUG 23 2025

01Z sfc analysis shows a cold front approaching from the
west that will eventually bring drier and cooler weather to the
area. For now though, some drier air has worked into the northern
parts of the JKL CWA while scattered showers and thunderstorms
are slowly fading out in the southern parts but not before
leaving behind some pockets of excessive rainfall. Currently,
temperatures are running in the low to mid 70s. Meanwhile, amid
light and variable winds, dewpoints vary from the lower 60s north
to the upper 60s and lower 70s south. Have updated the forecast
mainly to add in the latest obs and trends for the T/Td/Sky grids
but also to fine tune the PoPs and thunder chances through the
night per the current radar images and CAMs guidance. These
adjustments have been sent to the NDFD and web servers along
with a freshening of the zones, HWO, and SAFs.

&&

.SHORT TERM...(This evening through Sunday night)
Issued at 404 PM EDT SAT AUG 23 2025

The start of major changes is underway. A significant upper low
over Ontario is continuing to deepen as it moves slowly east.
Along with shortwaves rotating around it, its supporting
amplification of a large scale eastern CONUS trough. The falling
geopotential heights and increasing deep moisture over our
southern counties are favoring greater coverage of convective
precip today. The precip will linger into tonight, but should be
on an overall decline with loss of heating/instability. However,
with the support of the deepening trough, it may be slow to die
out.

The upper trough is supporting a cold front which is currently
moving southeast through the Midwest. It will move southeast
through the JKL forecast area on Sunday and Sunday evening. Some
regeneration of showers/thunderstorms is possible ahead of the
front on Sunday, but it now looks to be fairly limited in
southeast KY as somewhat drier air begins to arrive, especially
aloft. Much drier and cooler air eventually arrives behind the
front, being very noticeable by sunrise on Monday.

.LONG TERM...(Monday through Saturday)
Issued at 404 PM EDT SAT AUG 23 2025

The long-term period opens Monday morning with a deep 500 hPa
trough that extends south from James Bay, settling across the
Eastern CONUS. The surface cold front that passes in the short-
term will be well off to our south and east by that time, making
way for a cool and dry high pressure system sinking out of Central
Canada and across the Northern and Central Plains.

The deep 500 hPa trough will persist over the Ohio Valley/Central
Appalachian regions through Friday, with the lowest heights
occurring Tuesday evening with the passage of an embedded
shortwave trough. Even though the shortwave disturbance is quite
potent, moisture is limited (PWATs of 0.50 to 0.75 inches),
leading to a dry forecast. Behind that disturbance, the latest
LREF shows mean 850 hPa temperatures reaching the lowest values of
the period early Wednesday morning, between 7 and 9 degrees
Celsius. Shortwave ridging does build in Wednesday/Wednesday
evening accompanied by surface high pressure cresting over the
Ohio Valley. These conditions favor the two coldest nights of the
period being Tuesday night (when the coolest air mass is in place)
and Wednesday night (when the best radiative cooling conditions
are in place). Another shortwave trough, embedded in the parent
trough, drops out of central/eastern Canada on Thursday into
Friday. By that time though, the axis of the upper level trough
will be a little further east and a bit dampened, which keeps the
better surge of reinforcing cool and dry air to our northeast.
However, it will still be close enough to slow the return of more
typical late-summer temperature and moisture levels. In fact,
temperatures on the coolest days could easily run 10+ degrees
below normal. The trough finally lifts out to the northeast
heading into the weekend, allowing temperatures to return to
seasonable values.

In sensible terms, look for a cool and dry stretch of weather from
Monday into early Friday 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 50F or lower while
daytime highs will struggle to surpass 75F in all but the warmest
spots. Heading into Labor Day weekend, high temperatures are
forecast to reach the upper 70s to lower 80s for most locales
while nighttime lows range in the 50s. Fog formation is likely in
the favored river valleys on most nights.&&

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
ISSUED AT 751 PM EDT SAT AUG 23 2025

Thunderstorm activity over southeast KY looks to be downstream of
the terminals this evening, so the predominant weather is mid
level as. Some few sc will break up with the setting sun, so this
scattered cloud layer is notably absent in most TAF locations for
the next few hours. Higher clouds around 20kft will work in from
the northwest this evening and linger over the region through
tomorrow morning, with a quick clearing expected 16Z-17Z.

Light and variable wind overnight will lead to fog at most
locations, but SYM looks to have a 1-2 deg Tdd which appears to be
a limiting factor for fog formation here. IFR vsbys are expected
at LOZ and SME, with MVFR vsbys at JKL and SJS.

West winds will pick up tomorrow to 8-10kt. Some gusts to 18kt
are possible in the afternoon at SME and SYM but confidence was
too low to put in at this issuance.

&&

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

&&

$$

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