Alert archive / Indiana / Mesoscale Discussions in 2025

Mesoscale Discussion 913

May 20, 2025Vermilion County, Illinois; 6 counties in Indiana

The Storm Prediction Center issued this mesoscale discussion at May 20, 2025, 5:51 PM CDT for Vermilion County, Illinois; 6 counties in Indiana. It was in force for 54 min.

The area

The outline as issued.

The facts

Issued: May 20, 2025, 5:51 PM CDT (22:51 UTC)
Expired: May 20, 2025, 6:45 PM CDT
In force: 54 min
Issued by: the Storm Prediction Center
Concerning: Severe thunderstorm watch 304

Counties Vermilion County, IL, Benton County, IN, Fountain County, IN, Montgomery County, IN, Parke County, IN, Vermillion County, IN, Warren County, IN

The radar

The Indianapolis radar (KIND), 117 km from the middle of the area, began a volume at 22:52 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 nearest sounding before it

Lincoln, IL (KILX), launched 12:00Z, 10.9 hours before the alert went out and 93 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.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 562 m above ground
0-6 km bulk shear: 65 kt
0-1 km storm-relative helicity: 634 m²/s²
0-3 km storm-relative helicity: 684 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.4

Open this sounding in Storm Lab

The text

As transmitted.

799 
ACUS11 KWNS 202252
SWOMCD
SPC MCD 202251 
INZ000-ILZ000-202345-

Mesoscale Discussion 0913
NWS Storm Prediction Center Norman OK
0551 PM CDT Tue May 20 2025

Areas affected...Parts of east-central Illinois and west-central
Indiana

Concerning...Severe Thunderstorm Watch 304...

Valid 202251Z - 202345Z

The severe weather threat for Severe Thunderstorm Watch 304
continues.

SUMMARY...The tornado threat is likely peaking now (as of 2245Z),
and should lessen with northeastward extent over the next hour.

DISCUSSION...A supercell with a history of producing tornadoes (and
a couple upstream cells) are tracking eastward toward the cool side
of a warm front, though they are still in a very localized corridor
of surface-based instability and 150-200 m2/s2 effective SRH.
Therefore, the tornado threat is likely peaking now with this
activity, before it moves to the cool/stable side of the boundary.

..Weinman.. 05/20/2025

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...IND...LOT...ILX...

LAT...LON   40068795 40368811 40608783 40688744 40558723 39998677
            39708696 39718730 40068795 

MOST PROBABLE PEAK TORNADO INTENSITY...100-130 MPH
MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 19, 7:36 PM CDT	Mesoscale Discussion	SPC	Calhoun, Jersey, Monroe, Randolph, Saint Clair	2 hr
May 19, 8:26 PM CDT	Tornado Watch	SPC	Alexander, Bond, Calhoun, Clinton, Fayette, Franklin and 17 more	7 hr
May 19, 10:42 PM CDT	Mesoscale Discussion	SPC	Bond, Calhoun, Clinton, Jackson, Jersey, Madison and 5 more	2 hr
May 20, 1:07 AM CDT	Mesoscale Discussion	SPC	Alexander, Bond, Clay, Clinton, Crawford, Edwards and 27 more	83 min
May 20, 2:15 AM CDT	Tornado Watch	SPC	Clay, Edwards, Gallatin, Hamilton, Hardin, Lawrence and 7 more	4 hr
May 20, 1:09 PM CDT	Tornado Watch	SPC	Alexander, Johnson, Massac, Pope, Pulaski, Union	8 hr
May 20, 1:42 PM CDT	Tornado Watch	SPC	Bureau, Cass, Champaign, Christian, Clark, Coles and 31 more	6 hr
May 20, 1:44 PM CDT	Mesoscale Discussion	SPC	Champaign, Christian, Clark, Coles, Crawford, Cumberland and 15 more	106 min
May 20, 2:36 PM CDT	Tornado Watch	SPC	Hardin	8 hr

Nearby

Mesoscale Discussions in Indiana, 2025 Mesoscale Discussions in Illinois, 2025 Every mesoscale discussion in 2025

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.