JKL issues Area Forecast Discussion (AFD) at Sep 28, 4:46 PM EDT817
FXUS63 KJKL 282046
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
446 PM EDT Mon Sep 28 2026
.KEY MESSAGES...
- High pressure supports cool early autumn weather for the start
of the week.
- Warmer temperatures return from the middle to the end of the
week, along with our next reasonable shot at seeing some rain.
&&
.SHORT TERM...(This evening through Tuesday night)
Issued at 245 PM EDT MON SEP 28 2026
A cool, dry, and stable air mass remains in place over eastern
Kentucky under surface high pressure and north-northwesterly flow
aloft between upstream ridging extending from Texas to the Great
Lakes and a large downstream occluded low over southern New
England.
Northwesterly upper flow will continue but will decrease with
time as the upper ridge axis moves over the Ohio Valley Tuesday
night. This will occur as the downstream occluded low departs to
farther to the northeast while leaving a remnant upper trough
along the Eastern Seaboard. Surface high pressure ridging will
continue to slide east with time, allowing for surface winds to
gradually become more south to southeasterly by the end of the
short-term. This will mean a change from continued weak cold
advection today to neutral advection tonight into Tuesday, before
weak warm advection commences Tuesday evening through the
overnight.
Manual edits were made to lower dew point temperatures,
especially during the afternoon periods, and for ridge-valley
splits with MinTs, primarily during the evening through overnight
periods. Otherwise, the forecast is fairly quiet with minimal
edits needed otherwise.
Temperatures will rise several degrees Tuesday from today, as
skies remain sunny and advection trends more neutral. Nighttime
lows will also rise each night through Tuesday night, but not as
much so especially in the valleys. Expect continued fog formation
both tonight and Tuesday night, with locally dense fog probable in
some locations, likely to be covered again by Special Weather
Statements.
.LONG TERM...(Wednesday through Monday)
Issued at 446 PM EDT MON SEP 28 2026
The long-term period opens Wednesday morning with upper level
ridging in place over the Southeast CONUS, mirrored at the surface
by high pressure offset to the east over the Western Atlantic. This
will be maintaining a mild southerly flow across the Ohio Valley.
Looking upstream, a mean 500 hPa trough will be in place over
western Canada while a closed ~568 dam low spins over the Lower
Colorado River Valley. The trough will be supporting an ~991 mb
surface low over the Upper Mackenzie River Valley with a cold front
extending southward into the Northern High Plains and then westward
across the Columbia River Basin. Another ~1000 mb low is noted over
the Southern Rockies ahead of the aforementioned closed low.
For the first few days of the long-term, the upper level ridging
will drift eastward to off the Southeast Coast. This will keep
southerly flow and an unseasonably warm air mass (mean 850 hPa
temperatures ~16-18C, as per the LREF) and mostly dry conditions in
place over eastern Kentucky through Friday. In the meantime, the
closed low over the Desert Southwest will open up and be captured
the eastward-propagating northern-stream trough. As that trough
shifts eastward, it will suppress the 500 hPa ridging over the Ohio
Valley, transitioning the flow aloft to quasi-zonal/weakly troughed.
The cold front associated with the trough will move into the Ohio
Valley but then struggle to make further southeastward progress
Friday night-Saturday night as energy ejects out of the opening low
and rides along the boundary. Meanwhile, PWATs could exceed the 90th
percentile if the NAEFS/ECMWF mean solution materializes, amidst
deep moisture advection from the Gulf of America. If ingredients
come together ideally, a decent soaking rainfall is possible across
portions of eastern Kentucky or adjacent regions this weekend, but
forecaster confidence is low. From a more sensible standpoint, this
pattern will bring back the return of a summer-like feel for the
remainder of the work week with dew points recovering back through
the 50s and into the 60s while afternoon temperatures peak in the
low to mid 80s from Wednesday through Friday. Some of the hotter
portions of the Cumberland could flirt with the upper 80s. Rain
chances will then knock back the high temperatures for Saturday but
it will still be quite humid with the threat of rainfall and
possibly a few rumbles of thunder.
Change will be around the corner to close out the first weekend of
October. Within the broad upper level troughing, a quick-moving
shortwave trough transiting the 49th Parallel (US-Canada border)
over the weekend will phase with northern stream energy diving
southeast from the Yukon. This will bring height falls to the Ohio
Valley early next week while slinging an associated cold front
across the Coalfields Sunday into Monday. Behind that front, LREF
mean 850 hPa temperatures drop to ~9-11C with much drier PWATs (0.6
to 0.8 inches) by late Monday. Rain chances taper off behind the
first cold front on Sunday and appear minimal with this second
boundary. Instead, the more noticeable effect will be a decline in
temperatures to more seasonable levels for Monday with highs
returning to the mid 60s to lower 70s and cool nighttime lows in the
40s and 50s.
&&
.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
ISSUED AT 151 PM EDT MON SEP 28 2026
VFR conditions are expected with light winds through the period,
with the one exception being valley fog development late this
evening and continuing into the couple of hours after sunrise
Tuesday morning. Models continue to show the best moisture to the
east, so fog may linger to 14z or slightly later before fully
dissipating in some locations. As of right now, fog is not
expected to impact TAF locations for an extended period of time,
so will leave out and let future TAF issuances address this as
confidence hopefully increases.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...CMC
LONG TERM...GEERTSON
AVIATION...CMC
Source:
JKL issues Area Forecast Discussion (AFD) at Sep 28, 4:46 PM EDT---------------
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