877
FXUS63 KLMK 201137
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
737 AM EDT Thu Aug 20 2026

...Updated Aviation Discussion...

.KEY MESSAGES...

* A cold front pushing into the area from the north tonight will
  bring numerous showers and thunderstorms. A few strong to severe
  storms will be possible, especially west of I-65. Damaging winds
  and localized flash flooding are the main threats with storms.

* Low chances for showers and storms (<20%) linger for Friday-
  Saturday with warm temperatures in the low to mid 80s.

* After a brief cooldown this weekend, low chances for showers stick
  around through midweek next week.

&&

.SHORT TERM /THROUGH FRIDAY/...
Issued at 301 AM EDT Thu Aug 20 2026

     Through Daybreak Thursday...

Looking across the region this morning, there are multiple clusters
of showers and thunderstorms approaching southern Indiana and south
central Kentucky. Two clusters of storms are currently in
western Kentucky, with the northern cluster moving eastward and
currently moving over Ohio County. This cluster has been sub-
severe so far, producing a 36 mph gust in Crittenden County earlier
in the night. The southern cluster has produced > 80 mph winds, as
well as a radar-confirmed tornado. This cluster is moving more in an
ESE direction along the KY/TN border, currently moving over Logan
County. A third cluster/line of severe-warned storms has
also developed in west-central Indiana, moving southeastward
towards southern Indiana and entering the far northern CWA in the
next 1-2 hours.

Per the latest SPC mesoanalysis, surface-based instability is rather
meager over southern Indiana and central Kentucky (<300 J/kg), with
drier low-level moisture and a stable surface layer in place. The
main features that are driving these storms is increased elevated
instability (500-1000 J/kg MUCAPE), as well as a 30-40 kt low-level
jet over SW Kentucky, SE Missouri, and W Tennessee, and a mid-level
jet maxima (40-50 kt). The placement of these jet features has
resulted in 35-45 kt of effective bulk shear over western Kentucky
and southwestern Indiana, along with 200-300 m2/s2 of ESRH over
western Kentucky. With that said, the most recent guidance continues
to suggest that the environment will become less favorable as it
moves over central Kentucky and southern Indiana through the
remainder of the overnight. The main thing to look out for will be
the backbuilding of showers and storms over south central Kentucky
as a result of the enhanced LLJ. This could pose a localized
flooding concern for places south of I-64, where a Flood Watch is
currently out until 8 AM EDT. From the latest HREF 6 hour LPMM,
swaths of 2-3+" rainfall totals are still outlined for areas west
of I-65 and south of I-64, with 1-2" swaths to the east as the
system slowly weakens. Overall, the concern for strong to severe
storms (damaging winds is primary threat) remains in our far western
CWA, where a Severe Thunderstorm Watch is out for Logan, Simpson,
Warren, Butler, and Allen counties until 7 AM EDT. The line of
storms in Indiana could produce some gusty winds, but with weaker
winds shear and instability, the severe potential is on the lower
end.

     Daybreak Thursday through Thursday Night...

The clusters of showers and thunderstorms will be in our far eastern
CWA in east central Kentucky by daybreak as a weak surface cold
front moves in from the northwest. This features will slowly drift
over the region on Thursday, departing to the south and east by
Thursday evening. Chances for showers and thunderstorms will also
decrease throughout the day, with only 35% or less POPs by midday.
Elevated SBCAPE (1000-1500 J/kg) during the afternoon hours,
especially along and south of the Ohio River, could help spark some
isolated showers and storms across the area. Thankfully, wind shear
will be reduced and will keep the potential for strong to severe
storms to near zero. Afternoon highs across the region will be in
the low to mid 80s, with overnight lows in the mid to upper 60s
forecast. Once the cold front pushes through, surface high pressure
and low-level dry air fills in over southern Indiana and central
Kentucky, setting up a period of mostly dry conditions to end the
workweek.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Issued at 301 AM EDT Thu Aug 20 2026

=====Friday - Midweek=====

The weak cold frontal boundary moving through the area should slowly
clear our SE communities though remain close enough for increased
cloud cover Friday morning in the SE. Further towards the NW in
southern IN and along the Ohio River, clearing skies may allow for
fog formation as dew points will remain elevated in the upper 60s at
least. Further towards the south, there may be enough remnant
moisture for some morning-daytime showers and perhaps a rumble of
thunder. PoPs remain low for these areas as there still remains
uncertainty on if an impulse of activity along the Appalachians can
form to create more shower coverage for KY. Otherwise, temperatures
remain warm low to mid 80s with light southerly winds.

For the weekend, the synoptic scale flow features a deep digging
trough over the eastern CONUS, further supported by strong ridging
upstream over the mountain west of CONUS. With a high at the
surface, conditions should at least initially be dry Saturday.
Depending on a shortwave expected to move into the eastern US,
spotty to scattered convection may return in the afternoon. However,
there is a growing trend to keep the trough axis too far east to
feature any really impactful storms in our CWA. For now, low
afternoon PoPs will remain Saturday night into Sunday.

Once the shortwave passes, slightly and much drier air should filter
into the lower Ohio Valley for Sunday, making conditions feel much
less muggy. Sunday should mostly be dry as well. Highs reach the mid
to upper 80s Saturday to the low 80s Sunday. As for early next week,
troughing over the eastern seaboard of the US seems to persist and
we`ll be in between that and a ridge to our west. Being on the
periphery of continuous NW flow, any little disturbance traveling
along this flow will continue to keep low PoPs in place. Highs are
cooler to start, gradually warming as the week progress from the low
80s to upper 80s by Wednesday.

&&

.AVIATION /12Z TAFS THROUGH 18Z FRIDAY/...
Issued at 736 AM EDT Thu Aug 20 2026

Over the next 1-2 hours, showers and thunderstorms will clear out of
the area, with occasional VIS/CIG drops expected with any heavier
showers. For the remainder of the morning and into the early
afternoon, the main impact to flight categories should come from low
stratus, with low MVFR ceilings gradually scattering out later
today. As a cold front sinks from north to south, winds will veer
from southwesterly this morning to the north by this evening before
going light and variable tonight.

VFR conditions are expected for the afternoon and evening, with a
low (10-20%) chance for a shower or storm. Tonight, lingering low-
level moisture will lead to favorable conditions for fog, though
confidence in the magnitude and coverage of fog is low at this time.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...Flood Watch until 7 AM CDT this morning for KYZ026-027-061>064-
     070>078-081-082.
IN...None.

&&

$$

SHORT TERM...BEN
LONG TERM...BKF
AVIATION...CSG