116
FXUS63 KJKL 121708
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
108 PM EDT Fri Sep 12 2025

.KEY MESSAGES...

- Dry weather is expected to persist for the next week.

- Temperatures should warm above normal today and remain near that
  level well into next week.

&&

.UPDATE...
Issued at 105 PM EDT FRI SEP 12 2025

There are no significant changes to the forecast with the midday
update.

UPDATE Issued at 1030 AM EDT FRI SEP 12 2025

The valley fog has burned off everywhere except the Upper
Cumberland Basin, and it will most likely have burned off by the
top of the hour. Minor cloud adjustments have been made with the
late morning update, but the forecast is on track.

UPDATE Issued at 745 AM EDT FRI SEP 12 2025

The areal extent of fog and hourly temperature grids were updated
based on recent satellite and observation trends. Overall, this
led to no substantial changes at this time. Fog, initially dense
in some spots particularly near area lakes as well as the
Cumberland, Kentucky, and Big Sandy river should lift and
dissipate over the next couple of hours by the 9 to 10 AM
timeframe. High temperatures a couple of degrees above normal are
still anticipated.

&&

.SHORT TERM...(Today through Saturday)
Issued at 600 AM EDT FRI SEP 12 2025

Early this morning, the axis of an upper level trough extended
from the Northeast into portions of the Southeast east of the
crest of the Appalachians and eastern KY. To the west, an upper
level ridge extended from Mexico across the Southern Plains tot
he Upper MS Valley to Central Great Lakes. An upper level trough
continues to gradually evolve over the western Conus while an
upper level low was over northern Hudson Bay with a shortwave
trough south into northern Ontario. At the surface, a ridge of
high pressure extended from Quebec to the OH and TN Valleys.
Mostly clear to clear skies overnight and light winds have led to
the development of river valley fog over much of the Big Sandy,
KY, and Cumberland basins with patchy fog also evident in portions
of the Liking River Valley as well per satellite. In a few spots
this fog is likely to have become dense. Recently observed
temperatures ranged from the low 50s in the deeper sheltered
valleys to the upper 50s to low 60s on ridges.

Today and tonight, a gradual increase in 500 mb heights is
anticipated today with near neutral height tendencies tonight
with this occurring as the upper trough currently east of eastern
KY moves to near the eastern seaboard and upper level ridging
remains from the Southern Plains to MS Valley regions and also
east into the Southern and Central Appalachians. Further north,
the upper low initially over Hudson Bay is progged to move into
Quebec with the trailing shortwave trough working into the Great
Lakes. The ridge of sfc high pressure will continue to remain
across the region. Valley fog should gradually lift and dissipate
through around 10 AM EDT or about 2 to 3 hours past sunrise today
and give way to mostly sunny to sunny skies. Temperatures should
continue the upward trend of the past few days to a couple of
degrees above normal with low to mid 80s for all areas outside of
elevations above 2000 feet. Normal highs for today 80 at Jackson
and 81 for London. Under high pressure tonight, light winds and
mostly clear to clear skies will again favor valley fog
development along the larger creeks, area rivers, and lakes.
Another moderate magnitude ridge/valley temperature split is
anticipated with the normally colder locations bottoming out
around 50 with upper 50s for the coalfield ridges.

On Saturday, a slight decrease in 500 mb is anticipated as the
upper trough over eastern Canada to the Great Lakes passes by to
the north and northeast of eastern KY. At the same time, the
upper high should remain from northern Mexico and the Southern
Plains into the MS Valley region and portions of the Southeast
although weaken. The associated sfc high pressure ridge should
remain across the Appalachian region. Highs for Saturday should
be similar to today if not a degree or so warmer. With the
shortwave passing to the north and northeast some high and mid
level cloud cover should spread into the area during the
afternoon.

.LONG TERM...(Saturday night through Thursday)
Issued at 545 AM EDT FRI SEP 12 2025

The period is expected to begin with the axis of an upper level
ridge extending from Mexico across the SOuthern Plains to the mid
MS Valley to Upper MS Valley to Ontario with ridging also
extending into the Lower OH Valley/Appalachians. A weak lingering
trough is expected to extend from coast VA and the coast of the
Carolinas to off the GA coast to FL while a more potent rough
should extend from Quebec to the Northeast. Further west, an upper
trough should extend from Alberta to the Rockies/Four Corners
region with another series of shortwaves over the Pacific headed
toward BC and the Pacific Northwest. At the surface, a ridge of
high pressure should extend from the mid Atlantic states to the
Lower MS Valley/northern Gulf as the period begins.

From Saturday night to Sunday night, guidance generally lingers
an upper level trough from the VA coast to FL while tracking the
upper trough initially from Quebec to the Great Lakes the eastern
Great Lakes and St Lawrence Valley to the Maritimes and across
sections of the Northeast. Meanwhile, the upper ridge centered
over Northern Mexico to the Southern Plains builds into the Great
Lakes to MS Valley. Across eastern KY this upper pattern along
with sfc high pressure remaining across the Appalachians will
support mild/above normal temperatures, especially for highs on
Sunday with valley fog and a moderate magnitude ridge/valley
temperature split favored both Saturday and Sunday nights.

Monday to Tuesday night, guidance begins to diverge early next
week downstream of an upper level ridge extending from the
Southern Plains into the mid MS Valley and Great Lakes as far as
how lingering troughing near the eastern seaboard evolves. Recent
GFS runs keep more of an open wave/500 mb trough axis near the
eastern seaboard while ECMWF runs tend to close off an upper low
over SC and GA and track this system to near the GA and AL border
as mid week approaches. As is the case at midweek to the end of
the period, the GFS would be a warmer, sunnier, and entirely dry
solution with upper level and sfc ridging dominating. Meanwhile,
the ECMWF bring and increase in moisture into the Southern to
Central Appalachians including eastern KY by late Tuesday night
though precipitation is generally confined to near the crest of
the Appalachians/Blue Ridge east and southeast. Pops from NBM
PPI/POP of less than 10 percent were maintained during this
timeframe with the NBM generally middle of of the road
temperatures by the Tuesday to Tuesday night timeframe maintained.
If the GFS solution were to verify, temperatures would be on the
order of 5 or more degrees above normal versus the currently
forecast couple of degree above normal high temperatures for
Tuesday.

Wednesday to Thursday, as the period ends, the recent guidance
varies several dm with 500 heights across the Appalachians and
eastern KY areas. The past couple of GFS operational runs are
generally further east and closer to or east of the Southeast US
coast with an upper trough/broad upper level low with eastern KY
nearer to the axis of upper level ridging at midweek. Meanwhile,
the recent ECMWF operational runs have an upper low centered over
the Southeast vicinity of KATL and extending into the Southern
Appalachians near dawn on Wednesday. The recent GFS runs keep
higher heights/upper ridging the dominant influence on the weather
over eastern KY to end the period while recent ECMWF runs have
the upper low/open wave over the Southeast if not tracking it into
the Appalachians as is the case with the 00Z ECMWF operational
run with the 00Z ENS mean similar. At the very least, this leads
to uncertainty in temperatures and cloud cover, while the 00Z
ECMWF and ENS means suggest some showers are not completely out
of the question near the end of the period.

For now have kept the forecast dry per the NBM PPI and POP with
no more than 10 percent to end the period, while higher PPI and
pops south of the area nearer to the crest of the Appalachians.
The NBM temperatures were generally middle of the road among the
guidance so no changes were made to high temperatures. A bit of a
ridge/valley split was included for Wednesday night lows, though
if a solution nearer to the ECMWF or ENS mean were to verify cloud
cover would likely preclude such a split over most of if not all
of eastern KY.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
ISSUED AT 108 PM EDT FRI SEP 12 2025

VFR conditions are expected for the next 24 hours. The exception
will be fog developing in valleys once again during the 03Z to 12Z
timeframe. For this TAF package, have gone with a blend of
persistence and statistical guidance at KSME, indicating a period
of MVFR visibility, though sub-MVFR conditions are possible during
this time if fog occurs. With surface and upper level high
pressure dominating, winds will remain light and variable, except
through ~21z this afternoon when winds will be primarily out of
the northeast at 5 kts or less.


&&

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

&&

$$

UPDATE...CMC
SHORT TERM...JP
LONG TERM...JP
AVIATION...CMC