643
FXUS63 KLMK 170738
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
338 AM EDT Mon Aug 17 2026

.KEY MESSAGES...

* Another round of showers and storms is currently ongoing with an
  MCV moving through the region, departing by late Monday morning.
  Any storms that develop will have the capability of producing
  damaging winds and brief heavy rainfall.

* A few showers and isolated storms are possible Monday afternoon,
  especially east of I-75, with a very low likelihood in strong to
  severe storms occurring.

* A reprieve from the hot and humid weather, as well as showers and
  storms, comes Monday evening once the cold front departs to the
  south. Showers and storms arrive again for the mid and late week
  time frame, however temperatures should be slightly below normal
  for this time of year.

&&

.SHORT TERM /THROUGH TUESDAY NIGHT/...
Issued at 338 AM EDT Mon Aug 17 2026

A cluster of showers and thunderstorms currently over southern
Illinois and southwest Indiana is tracking eastward towards our CWA.
This cluster will move over southern Indiana and north central
Kentucky through the remainder of the overnight, exiting off to the
east by the mid-mornign hours. Per the latest SPC mesoanalysis,
while the cluster is in an area of 30-40 kt 0-6 km bulk shear thanks
to a modest low-level jet, the system will move away from the
highest area of elevated instability (~1500 J/kg MUCAPE) over the
coming hours, allowing it to weaken some as it moves over the area.
A low-level inversion over the region will also limit the potential
some for storms to become strong to severe, though gusty winds,
frequent lightning, and localized heavy rainfall will still be a
concern until the showers and storms considerably dissipate.

As this system moves through, a weak frontal boundary will slowly
push southeastward across the region, bringing with it a much-needed
reprieve from the heat and humidity experienced over the past
several days. There will be chances for showers and isolated
thunderstorms during the afternoon hours, with the concern for any
strong to severe storms being very low. For areas along and south of
the front (south central Kentucky) increased instability (HREF mean
CAPE > 2000 J/kg) will result in 40-60% chances of showers and
isolated storms. For places behind the front, chances for
precipitation will be much lower (15-30%). For afternoon
temperatures, highs for places north of the front will be in the mid
to upper 80s, with areas south of the front in the upper 80s/low 90s.

For Monday night, the cold front will finally depart off to our
southeast, with surface high pressure building in behind. In
addition to the temperature and humidity relief, this will also
provide a brief break from showers and storms over the region.
Overnight temperatures Monday and Tuesday night will be very
comfortable, with mid to upper 60s lows Tuesday morning and low to
mid 60s lows Wednesday morning forecast. For Tuesday afternoon,
expect temperatures in the low to mid 80s along and north of the
Parkways and in the upper 80s for areas south. Broad zonal flow
aloft will also prevail over the region starting early Tuesday and
continuing through the end of the short term forecast period.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Issued at 338 AM EDT Mon Aug 17 2026

While zonal flow will aloft will continue on Wednesday, a broader
pattern shift will begin to take place across most of the CONUS. The
upper ridge out west will amplify through the early portions of the
weekend as the upper trough over the eastern portions of the
country begins to dig southward. The initial digging of this trough
will come late Wednesday into Thursday as an embedded shortwave and
surface cold front moves towards the Ohio Valley. Conditions over
southern Indiana and central Kentucky will be dry for the daytime
hours, with highs in the mid to upper 80s forecast north of the
Parkways, and places getting into the low 90s south. Chances for
showers and storms will increase Wednesday night, with widespread
45-65% POPs forecast. There is still uncertainty in the guidance as
to whether these storms will line up with the best instability and
wind shear, so intensity of these storms is still uncertain.

The broad shortwave will slowly move through the region, finally
departing to the east by Friday. As a result, chances for showers
and storms (30-50%) will linger from late Wednesday night into early
Friday. Available moisture will slowly decrease as the previously-
mentioned frontal boundary pushes southward, exiting out of the area
by Thursday night. LREF PW of ~1.8" across the area late Wednesday
will decrease to less than 1.4" by Friday morning, which should help
limit the extent of persistent heavy rainfall. With the multiple
rounds of showers and storms, as well as the passing cold front,
afternoon temperatures will remain in the 80s Thursday and Friday,
with morning lows in the upper 60s Thursday and low to mid 60s
Friday.

The axis of the upper trough and an additional shortwave will move
over the region by the latter half of the weekend, though
deterministic and ensemble guidance shows varying outputs on the
timing and progression of these features. Lower end chances for
showers and storms will accompany these features, but once the axis
and shortwave moves through, calmer conditions are likely to follow.
Afternoon highs will be in the 80s, with morning lows in the 60s
Saturday and SUnday.

&&

.AVIATION /06Z TAFS THROUGH 12Z TUESDAY/...
Issued at 144 AM EDT Mon Aug 17 2026

A few showers and storms have developed near HNB and SDF, with a
lager cluster of storms over Illinois entering the region within the
next 1-2 hours. Very heavy rain, lightning, and gusty winds will
accompany these storms, impacting all terminals except BWG through
most of the morning hours. While ceilings should remain VFR, brief
MVFR visibilities are possible with heavier downpours. This cluster
should slowly dissipate as it moves east, departing out of the
region after 15z. Isolated to widely scattered showers and storms
could develop after 18z, with any activity dissipating by 00z. A
slow moving cold front will cause winds to shift from the SSW to the
NW for all terminals except for HNB from the late morning through
the afternoon hours, with winds steadily increasing during the
morning.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...None.
IN...None.

&&

$$

SHORT TERM...BEN
LONG TERM...BEN
AVIATION...BEN