433
FXUS63 KLMK 210804
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
404 AM EDT Tue Jul 21 2026

.KEY MESSAGES...

* Severe thunderstorms are likely from midday Tuesday through
  Tuesday evening, with all severe hazards possible. Damaging
  straight-line winds are the main hazard, but a few tornadoes and
  large hail will possible. Localized heavy rainfall may lead to
  flash flooding, especially east of I-65.

* Calm weather moves in with cooler than average highs for Wednesday
  through Friday this week.

&&

.SHORT TERM /THROUGH THIS AFTERNOON/...
Issued at 404 AM EDT Tue Jul 21 2026

Today, an upper ridge will begin to amplify northward into Canada as
an upper trough begins to drop south through the Upper Ohio Valley.
The upper trough will push a surface low east across Ontario and
into Quebec. The system`s cold front will drag south through the
Great Lakes and westward towards the Ozarks under northwest flow
directed towards the Ohio Valley. Ahead of the front, across the
CWA, precipitable water values sit between 1.5 to 2", but just ahead
of the front values will jump as high as 2.4", mainly west of
Interstate 65. This moisture as well as strong WAA will be driven by
10-15 mph southwest winds with gust to 20-25 mph. This will push
temperatures into the mid 80s to low 90s as dew points climb through
the 70s to near 80, again west of Interstate 65. It`s in this area
that heat indices have the best chance to reach 105. The heat
advisory extends farther east to make a pretty picture, but there is
a chance that remaining cloud cover from upstream convection over
Missouri and Illinois and our own convection could impact overall
warm temperatures and high humidities, especially in areas farther
north and east.

The severe threat continues to evolve. Yesterday it looked like we
would have two distinct lines of convection with one arriving during
the late morning and one during the afternoon/evening just ahead of
the cold front. Now, it`s looking more likely that there will be one
main line that could be broken or have supercells embedded or pass
through around the main line. All hazards remain with straight-line
wind being the main threat. MLCAPE levels remain high between 2,000
to just over 3,000 J/kg. Deep layer shear around 40 knots with areas
with backed surface winds, adding to a tornado threat. Model
soundings still show some areas with fairly stable low level lapse
rates or even elevated storms. This may be a little protection, but
would still expected parts of the area to see severe weather today.
Very high MUCAPE values in rotating updrafts could lead to large
hail.

It still appears, that thunderstorms will begin to move into parts
of southern Indiana around 16z with storms reaching Louisville
around 19-20z and Lexington around 20-21z as the surging part of the
line is expect to dive through the Bluegrass region a little
quicker. Areas farther west and south toward Bowling Green may see
storms anywhere from 21z to 02z Wednesday as the line drops a little
slower to the south.

There is also a flash flooding concern with the extremely high
precipitable water values. These values are high for any time of
year. Believe in general these storms will keep moving and reducing
their flooding risk, but with the expected heavy rainfall rates, any
area that see multiple storms could be a serious risk of flooding.
Because of this, we are issuing a flood watch along with our
neighbors.

&&

.LONG TERM /TONIGHT THROUGH MONDAY/...
Issued at 404 AM EDT Tue Jul 21 2026

Early tonight, most of the activity will be out of central Kentucky.
Winds will begin to ease as they veer towards the north. Skies will
try to clear and this could lead to areas of fog from earlier
moisture as temperatures fall into the mid 60s to low 70s.

Behind the front, surface high pressure will bring CAA and cooler
temperatures with highs in the upper 70s to mid 80s through Friday
before the high passes to the east and WAA returns, brining mid 80s
to low 90s back for the weekend. Dry weather is expect through the
end of the workweek with low-end rain chances returning around the
weekend into early next week as little surface systems ride in on
northwest flow.

&&

.AVIATION /06Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 211 AM EDT Tue Jul 21 2026

Convective activity over central Illinois and to areas farther to
the northwest are generating a layer of high level cloud debris that
is blowing southeast over southern Indiana and central Kentucky.
This along with some light winds should help limit fogging tonight,
but during the day, a cold front will bring a line of possibly
severe thunderstorms to area TAF sites. Sites should expect strong
gusty winds and reduced visibilities from heavy downpours. Hail is
also a concern in these storms.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...Heat Advisory from 10 AM this morning to 7 PM CDT this evening
     for KYZ023-024-026-027-061>063-070>076-081.
     Flood Watch from 1 PM EDT /noon CDT/ this afternoon through
     late tonight for KYZ034>043-045>049-053>057-063>067-
     073>078-081-082.
IN...Heat Advisory from 11 AM EDT /10 AM CDT/ this morning to 8 PM
     EDT /7 PM CDT/ this evening for INZ083-089.

&&

$$

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