EF2 tornado, Savanna to Mt Carroll, Illinois, June 12, 2013

1. EF065 to 85 mph

   Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.

2. EF186 to 110 mph

   Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.

3. EF2111 to 135 mphthis tornado

   Considerable damage. Roofs torn off well-built houses, frame homes shifted on their foundations, mobile homes destroyed, large trees snapped or uprooted, cars lifted off the ground.

4. EF3136 to 165 mph

   Severe damage. Whole stories of well-built houses destroyed, large buildings badly damaged, trains overturned, trees debarked, heavy cars lifted and thrown.

5. EF4166 to 200 mph

   Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.

6. EF5over 200 mph

   Incredible damage. Strong frame houses swept off their foundations, car-sized missiles thrown more than 100 meters, steel-reinforced concrete badly damaged, high-rise buildings deformed.

7. Unrated

   The survey recorded a tornado but could not put a number on it, most often because it crossed open country and damaged nothing a rating can be read from.

Rating

EF2

Date

June 12, 2013

Touchdown

6:53 PM CDT (23:53 UTC)

Lifted

7:03 PM CDT (00:03 UTC)

On the ground

10 minutes

Path length

6.6 miles (10.6 km)

Path width

880 yards (805 m)

Deaths

0

Injuries

1

County

Carroll County

Touchdown point

42.167, -90.150

Lift-off point

42.100, -90.058

Record number

1306121753-01

9 damage points were recorded along this path by NWS DVN, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF2. The highest wind the damage implies is 135 mph.

• Pole barn doors (had been closed and locked) were blown in.
• Dozens of large trees snapped. Trees hit cars.

Survey points are preliminary and are the raw material the published rating was built from. Source: NWS Damage Assessment Toolkit.

A surface low moved along a warm front into northwest Illinois and helped to focus thunderstorms along the Highway 20 corridor where the warm front was sitting in the early evening hours. Two supercell thunderstorms developed along the warm front and tracked southeastward, producing damaging winds along with two tornadoes. The first tornado touched down 3 miles south of Hanover and caused no significant damage. The tornado was on the ground for a half a mile. The second tornado touched down 6 miles north of Savanna and ended 4 miles west of Mount Carroll Illinois. The tornado was rated EF-2 with maximum winds of 135 mph, and one person was injured.

A NWS Survey team determined that EF2 tornado with maximum winds of 135 mph. The track began 6 miles north of Savanna and ended 4 miles west of Mount Carroll Illinois. The tornado was well defined with significant tree damage. Several farm outbuildings were damaged and one house was pushed off its foundation where the one injury occurred.

From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.

7 minutes of warning. NWS DVN issued a tornado warning for this county at 23:46 UTC, 7 minutes before the tornado touched down, in force until 00:15 UTC.

The county was under a tornado watch, issued at 18:51 UTC and running to 03:04 UTC.

Every warning and watch covering the touchdown point that day, from the Iowa Environmental Mesonet's archive of National Weather Service products. Lead time is measured from the issue of the warning in force to the touchdown time in the database, both of which were recorded to the minute by different people.

The Storm Prediction Center had this point in a High Risk, with a 0.15 chance of a tornado within 25 miles, in the hatched area where significant tornadoes were expected. The outlook in force was issued at 20:01 UTC.

SPC's Day 1 convective outlook as it stood when the tornado began, read at the touchdown point. The same archive is on the radar archive.

The radiosonde launches on either side of the tornado, from the nearest station that was launching then, drawn and analyzed the way Storm Lab does: the same diagram, the same parcel and shear definitions SPC's mesoanalysis uses.

Savanna (SFY), 10 km from the path, in the two hours either side.

From the Iowa Environmental Mesonet's archive of airport observations.

The Quad Cities radar (KDVN), 70 km away, was scanning. The volume nearest the touchdown began at 23:54 UTC.

Open the radar archive at this moment, over the track

Reflectivity and velocity, decoded from the Level II archive in the browser. Volumes take a few seconds to open the first time.

Local storm reports within 60 km of the path, in the three hours either side.

From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.

The live radar over the trackEvery 2013 tornado in IllinoisEvery tornado in Illinois since 1950Warnings in force in Illinois nowThe forecast where you are

20 more were confirmed in the United States that day.

Ratings are the survey's, read off the damage rather than measured; the rating scale is above. Tornado counts rise through the record as reporting improved, so a year in the 1950s is not comparable with one today except for the strongest tornadoes, which were always noticed.

NOAA Storm Prediction Center tornado database, 1950-2025, the official record kept by NOAA's Storm Prediction Center.