Alert archive / Indiana / Mesoscale Discussions in 2026
Mesoscale Discussion 1237
The Storm Prediction Center issued this mesoscale discussion at Jun 21, 2026, 6:53 PM CDT for 26 counties in Illinois; 31 counties in Indiana. It was in force for 97 min.
The area
The outline as issued.
The facts
- Issued
- Jun 21, 2026, 6:53 PM CDT (23:53 UTC)
- Expired
- Jun 21, 2026, 8:30 PM CDT
- In force
- 97 min
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 363...365
All 57 counties
Bond County, IL, Clark County, IL, Clay County, IL, Clinton County, IL, Coles County, IL, Crawford County, IL, Cumberland County, IL, Edwards County, IL, Effingham County, IL, Fayette County, IL, Franklin County, IL, Hamilton County, IL, Jackson County, IL, Jasper County, IL, Jefferson County, IL, Lawrence County, IL, Marion County, IL, Perry County, IL, Randolph County, IL, Richland County, IL, Saint Clair County, IL, Wabash County, IL, Washington County, IL, Wayne County, IL, White County, IL, Williamson County, IL, Bartholomew County, IN, Brown County, IN, Clay County, IN, Daviess County, IN, Decatur County, IN, Dubois County, IN, Gibson County, IN, Greene County, IN, Hendricks County, IN, Jackson County, IN, Jefferson County, IN, Jennings County, IN, Johnson County, IN, Knox County, IN, Lawrence County, IN, Marion County, IN, Martin County, IN, Monroe County, IN, Morgan County, IN, Orange County, IN, Owen County, IN, Pike County, IN, Posey County, IN, Putnam County, IN, Rush County, IN, Scott County, IN, Shelby County, IN, Sullivan County, IN, Vanderburgh County, IN, Vigo County, IN, Washington County, IN
The radar
The Evansville,IN radar (KVWX), 58 km from the middle of the area, began a volume at 23:57 UTC, the scan nearest the moment this went out.
Open the radar archive at this moment
The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.
The watches that followed
Watches SPC issued over any of the same counties within four hours of this discussion.
The nearest sounding before it
Lincoln, IL (KILX), launched 12:00Z, 11.9 hours before the alert went out and 166 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 1482 m above ground
- 0-6 km bulk shear
- 41 kt
- 0-1 km storm-relative helicity
- 10 m²/s²
- 0-3 km storm-relative helicity
- 35 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
607
ACUS11 KWNS 212354
SWOMCD
SPC MCD 212353
KYZ000-INZ000-ILZ000-MOZ000-220130-
Mesoscale Discussion 1237
NWS Storm Prediction Center Norman OK
0653 PM CDT Sun Jun 21 2026
Areas affected...southern Illinois into southern and central Indiana
Concerning...Tornado Watch 363...365...
Valid 212353Z - 220130Z
The severe weather threat for Tornado Watch 363, 365 continues.
SUMMARY...The tornado threat continues across Tornado Watches #363
and #365.
DISCUSSION...Supercells with a history of producing tornadoes are
ongoing across Tornado Watches #363 and #365 this evening. The
overall environment remains very favorable for thunderstorm
rotation, with effective-layer shear on the order of 40-50 knots and
0-3 kilometer SRH ranging from 400 m2/s2 from the Evansville, IN,
VAD to over 600 m2/s2 from the Indianapolis, IN, VAD.
Likely contributing to this enhanced low-level helicity is a strong
easterly component to the low-level wind field in response to an MCV
tracking northeast into central Indiana. As this MCV moves northeast
toward Indianapolis, increasing low-level theta-e to the south and
east of the MCV should be sufficient to offset the loss of diurnal
heating to maintain sufficient instability into the evening hours,
particularly across the watch area. Thus, the threat for
thunderstorms will continue. The threat for tornadoes will exist as
long as ongoing thunderstorms can remain sufficiently rooted in the
boundary layer to ingest these helicity-rich low-level air parcels.
As storms move east of I65, low-level theta-e quickly drops off and
storms should become increasingly elevated. As this occurs, the
overall tornado threat should lessen and a transition to strong,
damaging winds may occur before thunderstorms weaken.
..Marsh.. 06/21/2026
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...ILN...LMK...IND...PAH...ILX...LSX...
LAT...LON 38599018 39518828 39848672 39738536 38728522 38098731
37678889 37799007 38599018
MOST PROBABLE PEAK TORNADO INTENSITY...100-125 MPH
MOST PROBABLE PEAK WIND GUST...65-80 MPH
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 INSPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 21, 10:06 AM CDT | Mesoscale Discussion | SPC | Alexander, Bond, Clay, Clinton, Coles, Cumberland and 24 more | 114 min |
| Jun 21, 1:28 PM CDT | Tornado Watch | SPC | Bond, Christian, Clark, Clay, Clinton, Coles and 31 more | 9 hr |
| Jun 21, 2:34 PM CDT | Mesoscale Discussion | SPC | Clark, Clay, Crawford, Cumberland, Edwards, Effingham and 5 more | 116 min |
| Jun 21, 4:23 PM CDT | Mesoscale Discussion | SPC | Clark, Crawford, Edgar, Lawrence | 97 min |
| Jun 21, 4:43 PM CDT | Tornado Watch | SPC | Hamilton, White | 8 hr |
Nearby
Mesoscale Discussions in Indiana, 2026Mesoscale Discussions in Illinois, 2026Every mesoscale discussion in 2026
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.