JKL issues Area Forecast Discussion (AFD) at Oct 20, 2:01 PM EDT123
FXUS63 KJKL 201801
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
201 PM EDT Tue Oct 20 2026
.KEY MESSAGES...
- A light, mainly patchy, frost is possible again early this
morning and late tonight, primarily in sheltered valleys away
from lakes, rivers, and larger creeks.
- Expect near-normal temperatures throughout the work week, with
mostly clear skies and overnight ridge-valley temperature splits
likely to continue through at least next weekend.
&&
.UPDATE...
Issued at 725 AM EDT TUE OCT 20 2026
No significant changes were made to the forecast with mainly just
the inclusion of the latest obs and trends for the T/Td 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 OCT 20 2026
08Z sfc analysis shows a large area of high pressure holding
northeast of Kentucky and still in firm control of our weather.
This has meant another night of cloud free skies, light winds, and
dry dewpoints - near ideal conditions for radiational cooling. As
a result, a rather large ridge to valley temperature split has
developed along with thin trails of fog following the rivers -
likely locally dense. This limited fog has set up amid another
night probably featuring some patchy frost away from bodies of
water and in the more sheltered valleys. Currently, temperatures
are down in the upper 30s in a few of the valleys while ridges
have only slowly fallen into the low 50s. Meanwhile, dewpoints are
generally in the upper 30s to lower 40s.
The models, and their individual ensemble suites, are in pretty
good agreement aloft through the region during the short term
portion of the forecast. They all depict the southern 5h ridging
southwest of the area retrograding further to the southwest
allowing for a slight lowering of heights over eastern Kentucky
through Wednesday. This also enables weak northwest flow at mid-
levels to carry some weak, essentially harmless, energy packets
through our area. Given the rather small model spread, most of the
forecast grids came from unadjusted NBM data this morning.
However, did enhance the terrain distinctions again tonight on
account of the dry air and sfc high position while incorporating
the latest COOP MOS guidance. Did also drop afternoon dewpoints
and RH from the NBM numbers today and Wednesday considering deeper
mixing into drier air aloft. As for the PoPs - they are zero
through the period from the NBM and were kept that way since
ridging at the sfc dominates.
Sensible weather will feature a persistent forecast of cool/clear
nights and seasonally mild afternoons with plenty of sunshine. At
night, radiational cooling will again set the stage for a rather
large ridge to valley temperature difference. Look for narrow
areas of dense river valley fog to form after midnight dissipating
shortly after dawn along with a small potential for frost in the
most sheltered valleys.
The main changes to the NBM starting point were to adjust hourly
temperatures tonight for enhanced terrain effects given the dry
air and sfc high off to the northeast. Did also tweak dewpoints
and RH lower for this afternoon and Wednesday afternoon due to
deeper mixing into drier air found just off the sfc.
.LONG TERM...(Thursday through Tuesday)
Issued at 158 PM EDT TUE OCT 20 2026
Tranquil weather looks to continue through the long term period,
and with a fairly stagnant pattern in place, weather will change
very little from day to day. Aloft, a closed low will initially be
located off the coast of the Northeast, with midlevel troughing
over the eastern US; meanwhile, a strong and expansive ridge will
sit over the central CONUS. Over the course of the period, this
trough will gradually break down, allowing the ridge to expand
eastward closer to our area, though eastern Kentucky still looks
to be under the influence of ridging through early next week.
Thus, at the surface, models are in good agreement that high
pressure will dominate, keeping weather uneventful through the
forecast period. With such a dry air mass in place, even clouds
will be hard to come by through Saturday. Thus, expect plenty of
sunshine and high temperatures near average in the upper 60s and
low 70s. Each night, clear skies and a weak pressure gradient will
favor the development of ridge valley temperatures splits,
accompanied by typical valley fog. MOS guidance suggests that lows
will fall into the upper 30s in sheltered valleys and the low 40s
in most other locations, and this seems reasonable given this
pattern.
By early next week, a few clouds do look to return, associated
with increasing atmospheric moisture as the ridge expands eastward
and midlevel flow shifts from northerly to westerly. North of the
area, a trough will attempt to dig into the Midwest; however, our
persistent ridge will prevent this trough from pushing into our
area, even as it flattens a bit. At the surface, an area of low
pressure associated with this trough will translate east into
Quebec, with a cold front extending through the Great Lakes
region. However, given the upper level pattern and persistent
surface high pressure, this front is not expected to make it into
Kentucky by the end of the period. Model spread does increase by
Tuesday, with some disagreement regarding how quickly the ridge
breaks down. Even so, the most favored outcome at this time is yet
another pleasant fall day, with PoPs only peaking in the very low
single digits.
&&
.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
ISSUED AT 130 PM EDT TUE OCT 20 2026
High pressure will continue to keep the weather dry and lead to
mostly VFR conditions. The light winds and clear skies tonight
will promote the potential for mostly river valley fog late
tonight into Wednesday morning. This is not expected to affect
the TAF sites at this time. The winds will generally remain at 5
knots or less most of the period out of the northeast and east.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...GREIF
SHORT TERM...GREIF
LONG TERM...FAGAN
AVIATION...DJ
Source:
JKL issues Area Forecast Discussion (AFD) at Oct 20, 2:01 PM EDT---------------
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