277
FXUS63 KJKL 071150 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
750 AM EDT Mon Sep 7 2026

.KEY MESSAGES...

- Fair weather with more comfortable humidity is here for Labor
  Day, followed by temperatures and humidity creeping higher by
  mid week.

- A cold front looks to arrive on Thursday, bringing our next
  decent shot of showers and thunderstorms. Heavy to excessive
  rain is possible.

&&

.UPDATE...
Issued at 725 AM EDT MON SEP 7 2026

No significant changes were made to the forecast with mainly just
the inclusion of 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.

&&

.SHORT TERM...(Today through Tuesday)
Issued at 430 AM EDT MON SEP 7 2026

08Z sfc analysis shows a welcomed, but temporary, change in air
mass early this morning as a passing cold front has allowed drier
and cooler air to move into the area from the north. As such, the
northern parts of eastern Kentucky is getting a bigger taste of
this change than the southeast. In fact, a sfc trough axis is hung
up over our southeast mountains and likely contributing to a
batch of low stratus in this area while the higher dewpoints are
sustaining some patchy dense valley fog there. By the numbers -
temperatures vary from the low 60s in the north to near 70 degrees
in the far south. Likewise, dewpoints range from the dry mid 50s
north to the still quite sticky upper 60s in the south. The
thickest fog is indicated over the far southeast early this
morning.

The models, and their individual ensemble suites, are in pretty
good agreement aloft through the short term portion of the
forecast. They all depict a 5h trough still influencing the
weather over eastern Kentucky this morning. However, the
persistent ridge to the west is in the process of shifting back
this way for today and Tuesday pushing up the heights - bringing
in more heat and subsidence aloft for eastern Kentucky through the
end of the short term portion of the forecast. On account of the
very small model spread, mainly unadjusted NBM data were used for
the forecast grids. However, some small enhancements were made to
highlight terrain details in temperatures tonight and lower
dewpoints during the afternoons. Meanwhile, in addition to
including the most current consensus of the CAMs, PoPs were
adjusted up this afternoon to at least the 10 to 15 percent range
on account of enough signal in the CAMs for widely scattered
showers around peak heating. Subsidence will be stronger on
Tuesday justifying the near zero NBM PoPs.

Sensible weather will feature another relatively cool and pleasant
day with plenty of sunshine. A lee side trough on this side of the
Appalachian spine may be enough to trigger a few low meager
showers during peak heating - generally east and south of the
Mountain Parkway. This paltry convective threat ends by sunset -
lingering longest near Lake Cumberland - with clearing and good
radiational conditions setting up during the night. This will
allow for a moderate ridge to valley temperature spread as well as
probably a bit more extensive fog coverage in the more sheltered
spots. Tuesday looks drier and warmer as the sfc high to our east
strengthens - while a cold front steadily approaches to our
northwest.

The main adjustments to the NBM starting point included enhanced
terrain details in the upcoming overnight temperatures. As for
PoPs - had them peak near 15 percent for much of the southeast
late this afternoon - even in places that the NBM and latest CAM
runs kept dry - due to the potential for some light showers
developing before the drier air can effectively work into that
part of the area. The NBM PoPs near zero makes sense for Tuesday
and were left unchanged.

.LONG TERM...(Tuesday night through Sunday)
Issued at 455 AM EDT MON SEP 7 2026

The extended portion of the forecast remains on track with the
large 5h ridge being shunted south by a stronger northern stream
system Wednesday night through Thursday. The associated sfc front
may be wet enough to support excessive rainfall for parts of the
area and WPC has upped far eastern Kentucky to a Day 4 Slight
Risk of excessive rainfall on this account. We will need to keep
tracking this heavy rain potential during an otherwise benign
extended forecast period.

The previous long term discussion follows:

When the long term period opens, eastern Kentucky will again find
itself on the eastern fringe of an upper level ridge centered
over the Mississippi Valley. To the northwest, a closed upper
level low will be located over southern Saskatchewan. With time,
the low and its associated trough will translate east, helping to
flatten the ridge until the forecast area finds itself at the base
of a broad upper level trough late Wednesday into Thursday. Prior
to this, weather will be relatively quiet, with surface high
pressure located to the east of the forecast area on Tuesday.
Dewpoints should remain largely in the 60s except perhaps in our
westernmost counties; thus, although Tuesday will be unseasonably
hot, with high temperatures in the mid to upper 80s, it will not
feel as muggy. Overnight, clear skies and a weak pressure gradient
will allow a very modest ridge valley split to develop (on the
order of a few degrees), with typical valley fog development.
Moisture will return again Wednesday as the surface high sinks
south and winds become increasingly southwesterly, bringing
dewpoints back into the upper 60s or perhaps low 70s in our
westernmost counties. Highs will again climb into the upper 80s to
perhaps 90 in a few locations. Other than the lingering heat, no
impactful weather is expected.

The pattern begins to change by Wednesday night as upper level
troughing digs into the area. A surface cold front extending from
the now vertically stacked low over Canada will progress toward
Kentucky through the overnight hours, with rain chances increasing
in northeastern Kentucky as early as Thursday morning. There is
still some uncertainty regarding the exact timing of this front,
although ensemble guidance is hinting that rain would most likely
begin in the late morning or early afternoon for most of the
forecast area. There is high confidence that this front will
interact with an anomalously moist air mass; LREF mean PW values
are in the 1.6-1.8 range, generally representing at least the 80th
percentile compared to climatology. This, plus deterministic
model soundings showing a deep warm cloud layer, indicates that
any storms that form could be efficient rain producers capable of
unleashing torrential downpours. Given this environment, WPC has
introduced a Day 5 Marginal Risk for Excessive Rainfall for the
entire forecast area. Thankfully, the progressive nature of this
system, relatively dry antecedent conditions, and expected fast
storm motions should work to mitigate the flash flood threat
somewhat. Additionally, some machine learning guidance has also
picked up on a low end risk for severe thunderstorms on Thursday,
and given many deterministic models depict a belt of stronger mid
level flow just north of the forecast area, it is not
inconceivable that moderate shear (~30 kts) could support a more
organized storm mode as the front moves through. Even so, any
severe risk will remain heavily dependent on frontal timing, and
with the best shear along and north of the Ohio River, widespread
severe weather appears implausible at this time.

Model spread increases significantly following the passage of the
cold front. Some deterministic guidance is hinting that an
additional shortwave trough could spark additional rain chances
Friday afternoon into Friday night, particularly near the TN and
VA lines, while other model guidance suggests shortwave ridging
will build in, keeping the forecast area dry. Similar uncertainty
exists on Saturday. For now, NBM output has averaged these two
solutions, resulting in chance PoPs in the southern half of the
forecast area on Friday and Saturday afternoons, although this
will bear refining in the future. Ridging looks to build back in
by the end of the period, marking a return to a drier pattern.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
ISSUED AT 750 AM EDT MON SEP 7 2026

VFR conditions were present across the area at the 12Z TAF
issuance. Fog in the river valleys will dissipate shortly leaving
VFR conditions under a developing cumulus field. A stray shower
will be possible through the day though with minimal impacts on
any of the TAF terminals. Again any river valley fog is not
expected to affect the TAF sites tonight. Winds will be light and
variable through the period.

&&

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

&&

$$

UPDATE...GREIF
SHORT TERM...GREIF
LONG TERM...FAGAN/GREIF
AVIATION...GREIF