JKL issues Area Forecast Discussion (AFD) at Aug 19, 4:29 AM EDT760
FXUS63 KJKL 190829
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
429 AM EDT Wed Aug 19 2026
.KEY MESSAGES...
- Mainly dry weather through this evening, though locally dense
river valley fog is expected early this morning.
- A cold front brings scattered to widespread thunderstorms
tonight and Thursday, with a few strong wind gusts and
localized heavy rain and flooding possible.
- Noticeably cooler and less humid air arrives this weekend and
continues into early next week.
&&
.SHORT TERM...(Today through Thursday)
Issued at 409 AM EDT WED AUG 19 2026
A quiescent morning is underway across eastern Kentucky with fair
skies as surface high pressure crests over the central and
southern Appalachians. Thermometers range through the 60s, or
about 5 to 10 degrees cooler than this time yesterday--the coolest
that much of the area has seen in 2 weeks or more. Nighttime
Microphysics satellite imagery shows tendrils of fog weaving
through the deeper river valleys, growing thicker with time.
Looking aloft, a 500 hPa trough is situated over the Great Lakes.
Under this trough, a cold front extends from an ~1001 mb low over
Hudson Bay south to Lake Huron and then southwestward into
Iowa/Nebraska.
Through the short-term period, pockets of vorticity energy will
ride through the flow aloft carving out modest upper-level
troughing across the Ohio Valley. At the surface, this will
result in the aforementioned cold front sinking southward while
subtle waves of low pressure ride along it. Guidance is in fair
agreement showing the front reaching the Ohio River by ~12Z
Thursday and then slowly sagging into the Commonwealth, though
its farther southward progress will be very slow with little
upper-level support. PWATs of 1.0 to 1.2 inches this morning will
rebound in return flow to between 1.75 and 2.00 inches by late
tonight as the front approaches. This will result in a gradual
increase in cloud cover through the daylight hours.
While there are multiple clusters of convection upstream, the first
cluster, now over Missouri, is projected to dive southeast and
dissipate as it runs out of instability. Behind that, the return
of better moisture and instability develops out of the Mid-South.
RAP/HREF guidance supports the convective cluster now over South
Dakota diving southeast, with it or a descendant MCS approaching
the Commonwealth late tonight, entering a moderate instability
(1500 to 2500 J/kg of MUCAPE) and shear (35 to 45 kts of EBWD)
environment over the Mid-Mississippi Valley. As that MCS
progresses toward the eastern Kentucky Coalfields after 06Z
Thursday, it will move into a less favorable environment with much
weaker instability, leading to a gradual overall weakening trend.
However, HREF probabilities still support at least a 10% chance
of sustained winds greater than 30 kts (gusts likely higher)
within 25 miles of a point west of an imaginary line from Mount
Sterling to Irvine to London, suggestive of a risk for isolated
damaging wind gusts. This is closely mirrored by a Marginal Risk
(1/5) of severe weather noted in the SPC Day 1 Convective Outlook.
Convective coverage and intensity for most of the day on Thursday
will be dependent upon how quickly we are able to clear out behind
the MCS. So far, CAMs suggest modest post-MCS destabilization and
rather sparse convective initiation, which makes sense given only
weak upper-level forcing, slackening shear as winds weaken aloft,
and a possible weak capping layer between 850 and 700 hPa.
Another upper-level perturbation does approach late in the day,
weakening the capping and making convective initiation more
probable as we transition into the long-term period Thursday
evening. Overall late-day rain chances are highest over southern
and southeastern Kentucky, as the cold front will likely already
be working across or south of the I-64 corridor. The parameter
space would support torrential rainfall rates with any stronger
storms on Thursday, but again coverage is uncertain. WPC has
maintained a Marginal Risk ERO (1/4), indicative of the possibility
for isolated high-water issues.
In sensible weather terms, look for fog to lift and dissipate this
morning, giving way to mostly sunny skies. High clouds will
increasingly filter the sunshine as the day passes while a few
fair-weather cu could bubble up as well. It will be seasonably
warm with highs in the mid to upper 80s. For tonight, temperatures
fall back into the mid 60s to near 70F, with showers and thunderstorms
arriving from the west after midnight. Some of the storms could
be on the strong side, especially near and west of I-75. Looking
ahead to Thursday, most of the day is presently favored to be dry,
though hit-and-miss storms cannot be ruled out, especially south
of the Mountain Parkway late in the day. It will again be
seasonably warm with highs in the lower to mid 80s.
.LONG TERM...(Thursday night through Tuesday)
Issued at 429 AM EDT WED AUG 19 2026
As the frontal boundary associated with Thursday's convection
lingers near the area on Friday, shower and thunderstorm chances
will persist, with the highest probabilities during the afternoon
along and south of the Hal Rogers Parkway/KY Highway 80 corridor.
Beyond Friday, models and ensemble guidance remain in broad
agreement on a continued upper-level pattern featuring a ridge
over the western CONUS and troughing across the east, though
amplitude differences remain. Another shortwave embedded within
the longwave trough is projected to drop out of Northwest Canada
into the Great Lakes and Ohio Valley Saturday into Sunday. This
will drop another cold front across the Commonwealth, though
convective coverage and intensity is uncertain due to frontal
passage timing. A cool Canadian high pressure system follows that
cold front to kick off the last full week of August. However, the
quiet weather won't last very long as yet another shortwave
feature drops into the trough mid-week, bringing another cold
front with a renewed opportunity of convection across eastern
Kentucky, perhaps as early as Tuesday but more likely in the days
beyond the end of the forecast period. Temperatures will run not
far from seasonal norms, mostly in the lower to middle 80s for
afternoon highs while nighttime lows range in the lower to mid
60s. Some of the cooler sheltered valleys could dip into the 50s
early next week. Dew points could still be a bit sticky on Friday
- not far from the 70F mark - but should become much more
comfortable for the rest of the period.
&&
.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
ISSUED AT 157 AM EDT WED AUG 19 2026
High pressure is cresting over eastern Kentucky early this
morning and is bringing favorable conditions for extensive fog
formation in the valleys. The fog is likely to impact adjacent
ridges by daybreak, especially south of I-64. Reductions to at
least MVFR are forecast at JKL, LOZ, SME, and SJS, but could be
briefly worse. Confidence in fog formation was too low at IOB and
SYM to include in this TAF cycle. The fog will lift after
sunrise, allowing conditions to improve in all areas between 12
and 14Z. Light winds will continue through daybreak. West winds
at less than 10 kts then return by midday Wednesday with high
clouds and a few cumulus arriving after ~14Z.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...GEERTSON
LONG TERM...GINNICK/GEERTSON
AVIATION...GEERTSON
Source:
JKL issues Area Forecast Discussion (AFD) at Aug 19, 4:29 AM EDT---------------
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