851
FXUS63 KJKL 062027
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
427 PM EDT Sun Sep 6 2026

.KEY MESSAGES...

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

- A cold front is forecast to arrive on Thursday, bringing our
  next expectation of showers and thunderstorms.

&&

.SHORT TERM...(tonight through Monday night)
Issued at 412 PM EDT SUN SEP 6 2026

A cold front is sinking to our south this afternoon, supported by
upper level East Coast troughing. Surface high pressure behind the
front will slowly pass by to our northeast during the short term
period, with its air mass giving us a modest reprieve from heat
and humidity. Upper level ridging will begin to build in from the
west already on Monday, supporting warm readings despite the new
air mass. Both nights will probably have good radiating
conditions. There is some question regarding cloud cover, but
current thinking is that it will not be a significant hindrance,
and the coolest valleys could dip below 60. Valley fog is expected
both nights.

.LONG TERM...(Tuesday through Sunday)
Issued at 427 PM EDT SUN SEP 6 2026

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 18Z TAFS through 18Z Monday afternoon)
ISSUED AT 149 PM EDT SUN SEP 6 2026

Very isolated showers/thunderstorms persisted in far southeast KY
at TAF issuance, but will be winding down quickly. Conditions
across the area were generally a mix of VFR and MVFR (due to
ceilings). The ceilings will lift or breakup this afternoon,
leaving VFR conditions area wide to last well into the night. Fog
is forecast to develop in valleys late tonight, especially in
southeast KY. However, confidence in timing and extent is meager.
It would bring localized IFR or worse conditions, and may affect
some TAF sites. Fog will dissipate on Monday morning and leave VFR
conditions area wide to last into the afternoon.

&&

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

&&

$$

SHORT TERM...HAL
LONG TERM...HEF
AVIATION...HAL