JKL issues Area Forecast Discussion (AFD) at Oct 22, 8:04 AM EDT
036
FXUS63 KJKL 221204
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
804 AM EDT Thu Oct 22 2026
.KEY MESSAGES...
- Dry weather with mainly clear skies, mild days, and chilly
nights will persist well into week.
- Light, patchy frost may develop tonight and again late Friday
night in valleys away from lakes, rivers, and larger creeks.
&&
.SHORT TERM...(Today through Friday)
Issued at 403 AM EDT THU OCT 22 2026
Satellite imagery shows tentacles of fog expanding through the
deeper river valleys of eastern Kentucky early this morning.
Otherwise, skies are clear and starlit, and temperatures range
from the mid 30s in the coolest valleys to the upper 40s on thermal
belt ridges. A sprawling area of high pressure over the Central
CONUS remains centered near Duluth, MN. Looking aloft, a 500 hPa
ridge stretches from Texas northward to along the Manitoba/Ontario
border. A weak upper-level perturbation is noted over the Great
Lakes along the eastern side of that ridge.
Little substantive change is expected in the weather pattern over
the next 36 hours. The upper-level disturbance will dive southward
across the Commonwealth late this morning into midday, followed by
renewed weak low-level northeasterly CAA. That feed of cooler air
will ease on Friday as upper-level ridging begins to propagate
eastward again and the attendant surface high shifts east to the
St. Lawrence Valley, eventually causing low-level flow to veer
more easterly. With a slightly cooler air mass in place tonight,
the only concern of note will be patchy frost that could be more
extensive than the prior night. Otherwise, just anticipate routine
fog formation late tonight into Friday morning in the typically
favored valley locales.
In sensible terms, river valley fog and any frost this morning will
burn off and give way to sunny skies. It will again be seasonable
with high temperatures in the mid 60s to low 70s. Clear skies
follow tonight with fog in the favored river valleys and patchy
frost, mainly in the outlying colder hollows. It will be seasonably
chilly with lows ranging from the mid 30s in the coldest hollows to
the mid 40s on thermal belt ridges. Looking ahead to Friday, bright
sun returns with afternoon highs once again reaching the mid 60s to
low 70s.
.LONG TERM...(Friday night through Wednesday)
Issued at 804 AM EDT Thu Oct 22 2026
Confidence is high that the peaceful weather described above will
persist into the long term forecast period. Forecast guidance
collectively resolves a mid/upper level ridge building into the
Greater Ohio River Valley this weekend. Synoptic-scale subsidence
downstream of the ridge axis will keep skies clear and keep a
surface high pressure system nearby. The northerly orientation of
the flow aloft and the light/variable nature of the surface-level
winds will limit the amount of meaningful advection realized over
the CWA. So, given the dryness of the antecedent airmass, there are
no meaningful rain chances in the forecast for the next 7 days.
Ridging patterns like this favor efficient diurnal radiative and
mixing processes, and those processes will be the primary factor
governing Eastern Kentucky's sensible weather conditions through
early next week. Bountiful solar insolation and nocturnal ridge-
valley splits should yield 25-35 degree diurnal temperature ranges
each day. Subtle geopotential height rises suggest that Saturday and
Sunday's temperatures could fall on the higher end of the forecast
guidance envelope, and highs should reach widespread readings in the
the low/mid 70s each day. Lows will be more terrain-dependent, with
ridgetops remaining in the 40s as colder air pools in the valleys
after dark. The most sheltered and shaded valleys will see
temperatures cool down into the mid 30s, and patchy frost cannot be
entirely ruled out in these hollows. In the broader valleys, the
presence of rivers, lakes, creeks, and streams will favor fog
formation as lows drop into the upper 30s/lower 40s. More locations
should see fog than frost amidst the aforementioned warming trend,
but trends in afternoon dewpoint observations will need to be
monitored closely. If diurnal mixing is deep enough to mix down the
dry air aloft, the areal coverage of frost could be greater than
what is currently included in the forecast grids. It would not be
surprising if 20-30 degree dewpoint depressions are realized, and
the blended NBM guidance used to populate the long term forecast
grids is likely too moist. Small differences can make a big impact
when it comes to forecasting crossover temps and fog/frost, but
neither of these weather conditions would produce significant
impacts.
Such quiet weather can only persist for so long though, and the
ridging pattern is poised to gradually break down next week. As an
upper level trough ejects into the Plains on Monday, the ridge over
the Ohio Valley will flatten out. The resultant height falls point
towards a slight decrease in temperatures, and the flow aloft will
shift towards a more westerly and then southwesterly orientation by
Tuesday. This shift will introduce relatively greater amounts of
moisture to the column and thus some cloud cover back into the
forecast. Model spread begins to increase beyond then, as there are
differing solutions surrounding the trajectory and evolution of that
ejecting trough. Hazardous weather appears unlikely with this first
system, as there will not be much low-level moisture return out
ahead of its arrival and it will likely lose its upper atmospheric
support as time progresses. Some guidance suggests that there could
be some light precipitation on Wednesday, but ensemble probabilities
for measurable precipitation remain less than 15%. Thus, the
greatest changes in the forecast associated with this late-period
system will likely be tied to that increase in cloud cover. Expect
slightly cooler highs and slightly warmer lows as those clouds
modify the diurnal radiation budget, but temperatures should remain
in the same general upper 60s/lower 70s and low/mid 40s range.
&&
.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
ISSUED AT 734 AM EDT THU OCT 22 2026
Fog is bringing localized IFR or worse conditions to many valley
locations this morning, mainly away from the TAF sites. The fog
should lift/burn off by mid-morning, leaving clear skies and
light variable to northerly winds. Fog is possible in many valley
locations again late tonight.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...GEERTSON
LONG TERM...MARCUS
AVIATION...GEERTSON
Source: JKL issues Area Forecast Discussion (AFD) at Oct 22, 8:04 AM EDT (https://mesonet.agron.iastate.edu/p.php?pid=202610221204-KJKL-FXUS63-AFDJKL)
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