920
FXUS63 KLMK 180802
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
402 AM EDT Sat Jul 18 2026

.KEY MESSAGES...

* This afternoon and evening, scattered thunderstorms will bring
  heavy downpours, lightning, and gusty winds.

* Early tonight, a line of storms, ahead of a cold front, will drop
  south into southern Indiana before central kentucky. This line has
  the potential to produce damaging winds, mainly along and north of
  Interstate 64.

* Highs in the upper 80s to low 90s linger until Tuesday when a more
  substantial severe threat may occur in the evening with the main
  threat being gusty winds.

* Cooler than average temperatures move in from Wednesday through
  the weekend in the low to mid 80s.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 402 AM EDT Sat Jul 18 2026

As we begin a new day, many things remain the same. Precipitable
water values remain around 2 inches with temperatures near the dew
point in the low and mid 70s. This has led to some patchy fog, but
it is expected to quickly clear as the sun rises. Light winds and
cloud cover over parts of the area have helped to limit overall fog
coverage.

There is an upper trough axis sitting just to our east over eastern
Kentucky with an upper ridge axis running through the Rockies. This
is producing northwest flow that will push a surface low east
through southern Canada, just north of the Great Lakes. South of
this low, the low`s cold front stretches west to east, just north of
Indiana, but throughout the day, the front will dive south towards
our CWA.

Throughout the day, southern Indiana and central Kentucky will see
temperatures quickly warm into the mid 80s to low 90s. This will
help to once again drive instability with MLCAPE values reaching
between 1,500 to 2,500 J/kg generally across the CWA. With shear
remaining low, scattered pulse thunderstorms and showers are
expected. Any of these storms will be capable of producing
lightning, gusty winds, and heavy rainfall. The lack of winds make
these storms slow movers, leading to isolated flash flooding
threats, but overall, believe activity will be more scattered than
yesterday. The HREF 6-Hour PMM values look lower, hopefully limiting
the flooding threat.

Early tonight, the aforementioned cold front dropping south though
Indiana should be near Indianapolis. Ahead of the front, a west to
east oriented line of convection is expected to move towards the
CWA. Most model soundings over the CWA show a large stable layer
setting up early in the night, acting to protect the surface from
stronger winds, but soundings near Jefferson County, Indiana show
the line could arrive while still being surface based with around
1,200 J/kg of DCAPE. This would make it more likely for stronger
gusts to make it to the ground. This is in line with SPC`s outlook,
keeping the "Slight" mostly to our northeast. Before the line
becomes elevated and weakens, we are going to need to keep an eye on
our southern Indiana and northern Kentucky counties.

The rest of the night, this line will continue working south through
central Kentucky. This is expected to drop rain chances behind the
front as PWATs and dew points begin to drop. With widespread
rainfall and another night of near calm winds, patchy fog will
likely develop.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 402 AM EDT Sat Jul 18 2026

===== Sunday - Saturday =====

Beginning Sunday morning, leftover showers or maybe a weak storm may
be around by sunrise across our southern communities generally in a
west-to-east area from Ohio County towards Casey County KY and
points south. The cold front that will have caused the storms on
Saturday night will stall over this area, bisecting our CWA. PWATs
behind the cold front will drop considerably near 1.2-1.3" according
to the mean LREF guidance. In areas further south, PWATs will remain
somewhat elevated ranging 1.7-2.0" in the afternoon. Resultantly,
scattered storm coverage will return in these areas with dry
conditions for areas north of the cold front. Sunday in the south
won`t be a total washout, with some communities remaining dry.
Otherwise, rain totals have a 90% chance of remaining <0.5".
However, once CAMs begin running for the afternoon hours, wouldn`t
be surprised if isolated areas receive closer to 1-2" in the
heaviest of storms. Highs will be generally slightly cooler in the
north with mid to upper 80s with uniform upper 80s across the south.

By Monday morning, patchy fog may develop in rain soaked areas, but
begins calm with temperatures reaching the upper 80s across the
whole CWA with dewpoints increasing as the aforementioned cold front
begins lifting north again as a warm front. PWATs tick up in the
afternoon and spotty storms can`t be ruled out. A recent trend is
indicating a potent low over the Great Lakes will be approaching the
northern Ohio Valley, increasing SW flow late in the evening.
Depending on how far the warm front lifts Monday afternoon will
determine where convection will preferentially occur. As the potent
low approaches at low to mid levels, an MCS may develop ahead of the
resultant cold front that will form over the upper plains. A NW-SE
oriented CAPE gradient may develop and encroach upon our SW CWA.
This MCS, should one develop outside our CWA, may `chase` this CAPE
gradient moving SE and graze our western CWA bringing heavy
downpours and gusty winds late Monday night into the overnight hours
on Tuesday. There is still great uncertainty with this scenario
based on the location of this potential CAPE gradient and will be
monitored until the day arrives.

A more substantial severe storm threat is still trending for Tuesday
evening as the potent low swings off towards our NE, with the cold
front from the upper plains finally swinging through as well. A main
line of storms with decent 0-6km shear near 30-40kts may develop
allowing more organized storms to develop bringing gusty winds as
the main threat, possibly in the form of bow echos along an extended
line of storms. Severe probabilities remain low for now (<15%) but
the main threat seems to be strong winds. Highs on Tuesday will be
hot in the upper 80s and low 90s. Heat advisory criteria may be
met with heat indices in the low to mid 100s.

For the rest of the week, Tuesday`s cold front will clear the CWA
sometime early Wednesday, knocking highs down into the low to mid
80s and dry skies. Thursday through Saturday are trending cooler
than average as the overall synoptic pattern supports upper level
troughing in the eastern CONUS and ridging in the intermountain
west. Highs generally will remain in the low to mid 80s.

&&

.AVIATION /06Z TAFS THROUGH 12Z SUNDAY/...
Issued at 216 AM EDT Sat Jul 18 2026

Through the rest of the night, remaining showers are ending near
RGA. A rogue isolated shower will remain possible, but widespread
showers aren`t expected. With all the rain earlier, fog is also a
concern, but guidance currently looks optimistic with fog coverage
expected to be limited. During the day, expect another very humid
day with lots of moisture in the atmosphere. This is expected to
lead to more scattered afternoon and evening convection before a
west to east cold front drops south through southern Indiana and
central Kentucky, bringing a line of convection after 03z Sunday.

&&

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

&&

$$

SHORT TERM...KDW
LONG TERM...BKF
AVIATION...KDW