709
FXUS63 KJKL 212350 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
750 PM EDT Thu Aug 21 2025

.KEY MESSAGES...

- A cold front brings an area-wide potential for showers and
  thunderstorms during the weekend, with the greatest probability
  in southeast Kentucky.

- Noticeably colder and less humid weather will arrive by Monday
  and last through at least Thursday.

&&

.UPDATE...
Issued at 730 PM EDT THU AUG 21 2025

23Z sfc analysis shows high pressure building in from the
northwest that is in control of the weather over eastern
Kentucky. This is working to clear the skies and settle the winds.
Currently, temperatures are running in the mid to upper 70s.
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. These minor
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 Friday night)
Issued at 330 PM EDT THU AUG 21 2025

A frontal boundary is situated just southeast of the Appalachians
this afternoon. Only a modest local change in air mass has
occurred behind the front. However, clouds beneath the frontal
inversion have been slow to mix away. This has held temperatures
down and largely prevented convective precip so far today, even
though dew points near 70 linger in southeast KY.

Models are still insistent that clouds will overall break up for
tonight. If that does eventually occur, there should be valley fog
development, followed by dissipation on Friday morning. Fewer
clouds on Friday would allow for more warming than on Thursday. If
that`s the case, instability could allow for a few afternoon showers
or thunderstorms in southeast KY. However, forecast soundings
show that convective parcels would be rising through very dry air
aloft which, without any significant forcing, would not be
favorable for convective precip. Have used only a 20% POP in far
southeast KY. Any precip and most clouds then dry up on Friday
night as heating is lost, with radiative cooling and valley fog
eventually following.

.LONG TERM...(Saturday through Thursday)
Issued at 445 PM EDT THU AUG 21 2025

The period is expected to begin with upper troughing from the
Southern Appalachians to the northwestern Gulf coast/portions of
Southern TX with an upper low over Ontario and a more potent
shortwave south into the western Great Lakes to Upper and Mid MS
Valley regions. This will all be downstream from upper level
ridging centered west of the Four Corners and extending into the
Pacific Northwest to BC and also into portions of the Southern
Plains. At the surface, an inverted trough is still progged to
extend into parts of Central and eastern KY from the Gulf states
with a sfc low over Ontario and cold front south into the western
Great Lakes to mid MS Valley to Central Plains be more notable.
Sfc high pressure should initially be centered near the Albert and
Saskatchewan border and extend into parts of the Northern Rockies
to Northern Plains.

Saturday to Sunday night, the upper level low should move from
Ontario to near the Ontario and Quebec border with another shortwave
or two moving around the ridging over the western Conus into western
Canada and into the troughing and helping lead toward the evolution
of an upper trough from Canada into the eastern Conus. The first
shortwave trough should reach the Central Great Lakes to Lower OH
Valley late by Saturday evening into Saturday night and cross
eastern KY on Sunday with a secondary shortwave move into the
Great Lakes to OH Valley by late Sunday evening. The associated
sfc low is expected to track into Quebec over the weekend with
the trailing cold front sweeping across the Central and eastern
Great Lakes and into the Northeast to mid Atlantic states to
Southeast over the weekend. This boundary should cross eastern KY
during the late Saturday night to Sunday timeframe with sfc high
pressure nosing into the Lower OH Valley and TN Valley Sunday
night despite the approach of the next shortwave trough. This
frontal passage will usher in a transition to a cooler and drier
trend for next week. However, near and ahead of the boundary over
the weekend, showers and storms will be possible, generally
peaking diurnally. Guidance trends continue to support the higher
chances for convection both on Saturday and Sunday in the more
eastern and southern locations. Temperatures should remain near
normal for Saturday and Saturday night ahead of the front and then
trend to a few degrees below normal for Sunday into Sunday night.

Monday to Tuesday night, the axis of the upper level trough
should gradually work east across the Central and eastern Great
Lakes and OH Valley to Quebec to the mid Atlantic states to the
Appalachians downstream of upper level ridging centered in the
Southwest Conus to Southern Plains and Gulf that is progged to
that builds toward portions of the Central Conus at midweek. Sfc
high pressure will build into the Lower OH Valley region and
Appalachians from the Central and Northern Plains and mid and
Upper MS Valley into midweek. Cooler and drier air will be
ushered into eastern KY by the high` with temperatures expected
to be 10 to as much as 15 degrees below normal.

Wednesday to Thursday, some additional height rises should occur
over the Lower OH Valley through Wednesday with upper troughing
remaining from eastern Canada into the eastern Conus while upper
ridging remains from the western Gulf across the Southern Plains
to the Southwest Conus. North to northwest flow aloft and a sfc
ridge of high pressure will keep a continuation of below normal
temperatures and drier weather. Temperatures should remain about
10 degrees below normal into Wednesday night, with some moderation
on Thursday. Overall, the below normal and drier than normal
trend should persist to end the month of August per long range
guidance and CPC outlooks.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
ISSUED AT 750 PM EDT THU AUG 21 2025

Conditions have lifted to VFR for most places at the start of the
period, with a few spots still holding on to some MVFR CIGs. With
these clouds breaking up, fog will develop in valleys late tonight
and grow in breadth and depth with time until dawn, but probably
have little or no impact at the northern TAF sites. This fog will
bring localized IFR or worse conditions to the valleys perhaps
affect KSJS, KLOZ, and KSME. Any fog will dissipate by mid
morning, Friday, leaving VFR conditions for the rest of the day.
Winds will be light and generally from the north through the
period.

&&

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

&&

$$

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