658
FXUS63 KJKL 081409
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1009 AM EDT Tue Sep 8 2026

.KEY MESSAGES...

- Temperatures will inch higher through midweek, with humidity
  also climbing a bit into Wednesday and Thursday.

- A cold front moving into the area late in the week will give us
  our next expectation of showers and thunderstorms for Thursday
  or Thursday night.

&&

.UPDATE...
Issued at 1009 AM EDT TUE SEP 8 2026

Updated the forecast to include the latest observational and
model data across the region, particularly for the T/Td/Sky
grids. Early morning fog wording has been removed from the
forecast as fog has mixed out across the area. No major
adjustments were made to the forecast, and it remains on track.

UPDATE Issued at 720 AM EDT TUE SEP 8 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 Wednesday)
Issued at 425 AM EDT TUE SEP 8 2026

08Z sfc analysis shows high pressure off to the east of the state,
though there remains the hints of a lee side trough that was
partially responsible for a few stray showers late yesterday
afternoon and early evening. For this night, perhaps it kept a
bit more clouds around for eastern Kentucky, but clear skies did
dominate and allowed river valley fog to develop while the ridges
retained sufficient dewpoint depressions to keep such visibility
restrictions at bay. The mostly clear skies also supported a small
ridge to valley temperature difference thanks to limited
radiational cooling. Specifically, temperatures currently vary
from the mid 60s in the north and in the more sheltered locations
to the low 70s in the south and on the ridges. Likewise, dewpoints
range from the low to mid 60s north to the still rather sticky
upper 60s and lower 70s in the southwest.

The models, and their individual ensemble suites, are in very
good agreement aloft through the short term portion of the
forecast. They all depict 5h ridging building in from the west to
once again dominate the pattern over Kentucky. This ridge camps
out overhead through Wednesday, but never achieves the strength
for our area that it had earlier last month. As such it will
provide a fitting farewell to these waning days of summer with a
fitting reminder of the warmth and dry conditions we saw earlier
in August. Punctuating the fleeting nature of this ridge, by
Wednesday afternoon the active northern stream will start to press
south into the Ohio Valley and shunt the heat dome south of the
state. While through this point any mid level energy will be well
north of the JKL CWA it does hint at a return later Wednesday
night coming southeast out of the Upper Midwest. Again, on account
of the small model spread, the forecast grids contain mainly
unadjusted NBM data. However, some small enhancements were made to
highlight terrain details in temperatures tonight and slightly
lower dewpoints during the afternoons. Meanwhile, PoPs were left
in the low single digits to zero through the period in accordance
with the latest CAMs guidance.

Sensible weather will feature a slightly warmer day compared to
yesterday with humidity building. This extension of summer-time
heat will last into at least Wednesday, as well, with mostly
sunny skies and dry conditions. Heat indices peak around 90
degrees today and will be in the low to mid 90s for Wednesday. At
night, we will see continued mild conditions with a small ridge
to valley difference in temperatures along with typical river
valley fog development.

The main adjustments to the NBM starting point consisted of
enhanced terrain details for the upcoming overnight temperatures.
As for PoPs - kept them near zero through the period with little
adjustment from NBM needed.

.LONG TERM...(Wednesday night through Monday)
Issued at 500 AM EDT TUE SEP 8 2026

The extended portion of the forecast remains on track with a
fairly strong 5h trough working through the Ohio Valley to close
out the work week as the ridge retreats further to the south. The
trough`s associated sfc front may be wet enough to support
excessive rainfall for parts of the area on Thursday and Friday.
WPC has eastern Kentucky in a Day 3 and Day 4 Marginal Risk of
excessive rainfall. We will need to keep tracking this heavy rain
potential during an otherwise benign extended forecast period.

The previous long term discussion follows:

The period begins Wednesday morning with stout ridging over the
southern half of the CONUS, while an active zonal jet stream remains
across the far northern CONUS. The ridge will progressively get
shunted south and east through Thursday and into Friday as a
progressive shortwave pushes a cold front southeast into the
southern Ohio Valley. However, it appears that the shortwave may
outrun the surface front, leaving it to decay over or north of
eastern Kentucky into the weekend as mid-level ridging builds back
over the region.

The NBM was kept for the extended period, with the exception of
adding modest ridge-valley splits for Wednesday night into Thursday
morning ahead of the approaching system. Considerable uncertainty
arises in the greater synoptic pattern as the coming weekend
progresses into next week, particularly concerning the evolution of
a cut-off upper level low over the Pacific Northwest this weekend,
with downstream implications over the Midwest and Ohio Valley as
ensemble systems become increasingly out of phase with each other.

WPC has introduced a Slight Risk ERO for Thursday into Thursday
night across much of WV and into northeastern and far eastern
Kentucky. This is as the approaching system Thursday into Friday
will be intruding into a warm and humid environment characterized by
PWs peaking in the 90th-95th percentile (according to the LREF)
across much of the area northwest of the Cumberland Mountains. The
orientation of the front, the perpendicular upslope wind component
on the backside of the front, and the timing of arrival of heavy
rain and/or thunderstorms at or near peak heating all suggest some
potential for flash flooding along the windward side of the
Appalachians.

PoPs are continued into the weekend as it appears the front decays
over the region to end the week, with the potential for additional
shortwaves and possibly weak surface lows to initiate at least
spotty showers and thunderstorms across the area before mid-level
heights likely rise Sunday into Monday of next week.

There is high confidence that temperatures remain above normal
through the period, with the coolest day (and closest to normal
readings) coming Friday with the upper trough overhead. Highs will
generally be in the mid to upper 80s with lows mostly in the 60s,
though a few lower 70s readings are possible Wednesday night in the
warm humid environment ahead of the approaching front.

&&

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
ISSUED AT 730 AM EDT TUE SEP 8 2026

VFR conditions were present at 12Z issuance. Localized valley fog
will clear out shortly and then VFR conditions hold for the rest
of the period. Any valley fog that develops tonight is also
expected to not impact the TAF terminals. Look for winds to remain
light and variable through the period, as well.

&&

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

&&

$$

UPDATE...GINNICK
SHORT TERM...GREIF
LONG TERM...CMC/GREIF
AVIATION...GREIF