847
FXUS63 KJKL 170915
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
515 AM EDT Mon Aug 17 2026

.KEY MESSAGES...

- Multiple rounds of showers and thunderstorms are possible
  through this evening. Damaging wind gusts could occur in the
  strongest storms.

- A Flood Watch is in effect through this evening east of I-75.
  Torrential downpours on saturated ground pose a risk for
  isolated to scattered flash flooding.

- Dry weather returns Tuesday before another cold front brings
  additional thunderstorm chances Wednesday evening through
  Thursday, followed by cooler temperatures late in the week.

&&

.SHORT TERM...(Today through Tuesday)
Issued at 439 AM EDT MON AUG 17 2026

After an active evening of severe weather and flash flooding,
conditions across eastern Kentucky are mostly quiet early this
morning, outside of some patchy cloud cover and a stray
shower. It is also muggy and mild with temperatures ranging from
the upper 60s to lower 70s. All is not quiet upstream, however, as
regional radar mosaic imagery shows a rather large area of
convection riding the I-64 corridor eastward across southern
Indiana and Illinois, now approaching the Louisville, KY and
Cincinnati, OH metro areas. Mesoanalysis shows this convection is
associated with an incredibly moist pool of air, featuring PWATs
of up to 2.4 inches near Evansville, Indiana, and forced by a
pair of 500 hPa vort maxes--one over south-east Illinois and a
second near St. Louis, MO. The EBWD with this MCS is locally
maximized at around 35 kts, sufficient for organized multicellular
segments as well as embedded supercellular structures. Behind
this MCS is the long-awaited cold front that will finally bring
an end to our daily hit-and-miss torrential soakings, at least
temporarily.

The steering flow should favor the ongoing upstream MCS
continuing to progress eastward at about 25 to 30 kts,
reaching our northwestern doorstep by around daybreak. Convective
strength maintenance is uncertain as the instability over much of
eastern Kentucky is meager--generally 500 to 1000 J/kg of
MUCAPE-- given last evening`s convection. An overall weakening of
the MCS appears probable as it approaches eastern Kentucky, but
it seems unlikely that it will completely die out as some of the
CAMs have suggested. The big question will be how much
instability is able to build ahead and south of this MCS and its
parent vort maxes. Model forecast EBWD values appear to remain at
levels sufficient for organized multicell line segments and
perhaps even supercellular structures. Additionally, the 06Z RAP
continues to support 3000 to 3500 J/kg of MLCAPE nosing into the
southern side of this system by this afternoon, with DCAPE values
holding near 1000 J/kg while PWATs remain in the 2.0 to 2.25 inch
range. This parameter space should be supportive of at least
isolated strong to damaging wind gusts from collapsing, heavily
water-loaded updrafts, as well as from any line segments that
maintain a north-to-south orientation. The most favorable modeled
parameter space appears to be along and south of the Mountain
Parkway. The other concern will be a renewed flooding threat.
While individual cells should remain fairly progressive, the
extremely moist atmospheric profile will continue to support
extremely high rainfall rates. After last night`s convection,
3-hour FFG is only 1 to 2 inches for most locations east of I-75,
and that could easily be surpassed if multiple storms move over
the same location repeatedly. Therefore, the Flood Watch has been
expanded and extended through this evening--to ensure that all
convection up to and including the frontal passage is captured.
Most guidance has that front reaching the VA/KY border this
evening.

Behind the front, northwest upslope flow can be expected
overnight. This will tend to promote fog and/or low stratus
overnight, perhaps with a few lingering showers or instances of
drizzle. The air mass should then gradually dry out during the
day on Tuesday, allowing low stratus and fog to lift into a
fair-weather cumulus field, ending any lingering drizzle or
light rain showers. Temperature-wise, daily maximums are forecast
to reach the mid 80s north to low 90s south today, lowering to
mainly the lower to mid 80s on Tuesday. The air mass will also be
noticeably less humid on Tuesday, with dew points settling into
the 60s after ranging in the mid 70s for most places today.

.LONG TERM...(Tuesday night through Sunday)
Issued at 456 AM EDT MON AUG 17 2026

Dry weather will persist for most of Wednesday as surface high
pressure translates through the Central Appalachians. In its wake,
an upper level trough will be digging across the Great Lakes and
supporting a cold front sagging across the Ohio Valley. By
Wednesday evening, the front will approach eastern Kentucky and
rain chances will return to the JKL CWA. Of note, some models
depict an additional shortwave traversing the base of the trough
(roughly centered over the Ohio Valley) around the time frontally
forced convection approaches, or perhaps slightly before. This
enhanced mid level flow may elevate shear somewhat, and depending
on frontal timing, instability may also be adequate for stronger
storms, although model spread remains quite high at this time. Any
risk for severe weather (or lack thereof) remains dependent on
how these ingredients line up, with overall risk looking quite low
at this time. Meanwhile, a moist air mass will be in place ahead
of the front, with LREF mean PW values generally in the range of
1.6-1.7 in (roughly 80th percentile or higher compared to
climatology). This, in addition to potentially enhanced convective
coverage if shortwave energy interacts with the front, could
allow for at least isolated instances of flash flooding. Again,
model variability remains very high at this stage, but WPC has
already outlined northwestern portions of JKL area in a Day 3
Marginal (Level 1/4) Risk for Excessive Rainfall on Wednesday, and
an additional Day 4 Marginal Risk on Thursday as the system sags
south. Guidance does suggest the front will slow as it passes
through the southern portion of our area and into Tennessee.
Exactly how quickly this boundary progresses is still a source of
uncertainty, but rain chances have been maintained through
Thursday to account for this slowing motion. Any hydrological
concerns will also be dependent on the speed of this frontal
passage in addition to the extent of convective coverage.

Following the frontal passage, troughing will continue to
amplify, eventually digging all the way into the Southeast as
ridging retreats towards the Four Corners region. This will usher
in cooler weather, with high temperatures as low as the upper 70s
possible for some locations on Friday. Additional impulses will
keep at least scattered showers and storms in the forecast each
day, with rain chances generally peaking in the afternoon/evening.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
ISSUED AT 153 AM EDT MON AUG 17 2026

Aside from highly isolated weak convection, VFR conditions were
noted over the terminals at the 06Z TAF issuance. Given recent
rainfall, radiation fog formation is possible in the most
sheltered valley locations early this morning, but modest low-
level winds just off of the surface are likely to keep any more
widespread fog formation in check. A cold front will approach the
area during the daylight hours Monday with two or more rounds of
convection possible. The first round of storms is over the Lower
Ohio Valley and could reach more northern terminals by daybreak.
Guidance continues to struggle with the evolution of this system,
so forecast confidence in impacts at the terminals is somewhat
low. Another round of convection is then expected during the
afternoon and evening hours just ahead of/along the cold front.
Winds will generally be light and variable early this morning,
becoming southwest after daybreak before shifting northwest late
in the day behind the cold front. Winds will generally remain
around 10 kts or less, but could be locally strong and erratic
near thunderstorms.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
Flood Watch through this evening for KYZ044-050>052-058>060-068-
069-080-086>088-104-106>120.

&&

$$

SHORT TERM...GEERTSON
LONG TERM...FAGAN/GEERTSON
AVIATION...GEERTSON