EF1 tornado, Memphis to Otisco, Indiana, June 21, 2026

Area Forecast Discussion
National Weather Service Louisville KY
844 PM EDT Sun Jun 21 2026

.KEY MESSAGES...

* Strong to severe thunderstorms will be possible this evening into
  tonight. Damaging winds, isolated tornadoes, and flash flooding
  are the main threats.

&&

.MESOSCALE...
Issued at 844 PM EDT Sun Jun 21 2026

Cluster of multi-cellular and supercellular storms are currently in
progress across southern Indiana this evening.  Environment across
our northwest/northern CWA (focusing on southern IN) remain in a
favorable environment for continued tornado production.  Effective
layer shear values on the order of 40-45kts and 0-3KM ESRH values of
350-400 m2/s2 (based on VWX VWP) remain in place across the region.
Much of this low-level enhanced flow is being driven by the
convectively generated MCV moving across central IN.  So the storms
should continue to maintain themselves up to the I-65 corridor. East
of the I-65 corridor, mesoanalysis shows that low-level theta-e
drops off quickly and storms most likely will become elevated and
reverting from more of a tornado threat to a wind damage threat.

Further west, a more discrete supercell is in progress across
portions of Gibson/Pike county.  It remains in a favorable
shear/instability axis and will affect Dubois county over the next
hour.

Overall, the next 1-2 hours of focused severe weather will remain
north of the Ohio River across southern Indiana.  The cluster of
storms will eventually move into SE IN and into portions of northern
KY by 230-330Z.

&&

.SHORT TERM /THROUGH MONDAY/...
Issued at 355 PM EDT Sun Jun 21 2026

Ahead of a surface low, currently over northern Missouri, is an area
of convection stretching from St. Louis up through Peoria. Into the
overnight, this low will get pushed towards central Indiana by
junkie zonal flow and is expected to push the line of convection
towards southern Indiana and central Kentucky.

Ahead of the line, in southern Illinois and far western Kentucky dew
points are in the mid 70s. They taper off into the mid 60s over
southern Indiana and central Kentucky. Temperatures over the CWA are
in the low to mid 80s but will continue increasing a few degrees
being lifted by southern winds and mostly clear skies ahead of the
system.

Model agreement has improved greatly from 24 hours ago. CAMs have
the main line entering our southwestern Indiana counties around 23-
00z and continuing to push east and south through the CWA tonight.
This is entering an environment with crazy high precipitable water
values of 1.8 to 2.25+ inches. Anything near 2 inches is a lot and
has to put flash flooding concerns on the mind, so any place that
sees training storms, multiple waves, or slow moving storms could
pick up multiple inches in a short amount of time. Our 6 hours Flash
Flood Guidance ranges from 2.5 to 6 inches over southern Indiana and
central Kentucky with our southwestern counties, near Bowling Green,
being able to take that higher amount. Where we have the Flood Watch
in Indiana is closer to the low and where the higher chances
currently are for flooding. The flooding threat may end up being the
greatest threat this evening/tonight.

On the severe weather side, model soundings and hodographs dynamics
look favorable for tornadoes over southwestern Indiana. Deep layer 0-
6 km shear is over 40 knots. There is good turning with good inflow
in the low levels of the hodograph and low level SRH values are
high, but with the expected arrival of the line being when we lose
diurnal warming near sunset, a stable layer is expected to develop
at the surface. There will be a point to our west moving into our
area that surface based storms become more elevated where it will be
harder to get a tornado to the ground. LCLs are lower in some of the
guidance than they has been, and overall, instability remains fairly
weak with MLCAPE remaining under 1,000 J/kg. The better instability
remains south of Interstate 64 and west of Bowling Green. Believe
it's possible the stronger convection ends up missing a good chunk
of the CWA as convection chases the instability south through
western Kentucky while some activity stays with the low moving over
central Indiana.

By around 6z or a little after, the bulk of the convection will
likely be south and east of the CWA. For the rest of the night,
ceiling are expected to be low with isolated to scattered showers
likely.

Monday, the system's cold front will lag on the back side of the low
and is expected to push through during the afternoon hours. This
will veer winds towards the northwest, limiting highs to the mid to
upper 70s over southern Indiana and the low 80s over southern
Kentucky. Additional waves of showers and non-severe thunderstorms
will remain possible through Monday.

&&

.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
Issued at 355 PM EDT Sun Jun 21 2026

By Monday night, CAA is over the CWA as a large surface high gets
pushed east from the Plains through Indiana by Tuesday night. This
will bring a return of WAA on Wednesday, lifting temperatures that
were slightly below normal Tuesday and Wednesday back to near normal
by Thursday.

The CWA is expected to remain dry through Wednesday, but as the high
pushes off the the east, zonal flow will push small surface lows
from the Plains through the Ozarks into the Lower Ohio Valley. It
don't look like a washout, but shower and thunderstorms chances will
increase during this period. Towards the end of the week, a strong
ridge will likely bring warmer temperatures and drier weather.

&&

.AVIATION /00Z TAFS THROUGH 06Z TUESDAY/...
Issued at 748 PM EDT Sun Jun 21 2026

VFR conditions will continue from now until a broken line of storms
approaches from the west near 01Z at HNB, to near 05Z in south
and eastern airports. These storms will bring MVFR ceilings and
variable winds gusting up to 35kts or higher if individual cells
turn severe. Once the showers or storms roll through all
airports, ceilings will lower to low end MVFR and high end IFR,
with the lowest ceilings in the NW near HNB. Winds will continue
to blow from the S/SW until the storms end, eventually turning
out of the west later Monday afternoon. Ceilings are slow to
recover if much at all during the day on Monday remaining in
MVFR category through the afternoon. Thunderstorms may refire in
BWG/RGA later in the day, but otherwise airports remain dry
with MVFR conditions expected Monday afternoon.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...None.
IN...Flood Watch until 8 AM EDT /7 AM CDT/ Monday for INZ076>079-
     083-084-089>092.

&&

MESOSCALE....MJ
SHORT TERM...KDW
LONG TERM....KDW
AVIATION.....BKF