EF2 tornado, Mound City to Grantsburg, Illinois, May 25, 2011

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

May 25, 2011

Touchdown

6:55 PM CDT (23:55 UTC)

Lifted

7:14 PM CDT (00:14 UTC)

On the ground

19 minutes

Path length

19.9 miles (32.0 km)

Path width

325 yards (297 m)

Deaths

0

Injuries

0

Property damage

$255,000

Counties

Pulaski, Massac and Johnson counties

Touchdown point

37.220, -88.990

Lift-off point

37.406, -88.718

Record number

1105251755-01

Numerous strong to severe thunderstorms occurred in the warm sector of a low pressure system over central Missouri. The air mass in the warm sector was very unstable, with afternoon mixed-layer cape values in the 2500 to 4000 j/kg range. A 65 to 75 knot mid level jet was located across Arkansas, with the nose of the jet moving into western Kentucky. This feature enhanced the lift and strong deep-layer shear already in place, creating an environment very favorable for supercells and tornadoes. A 40 to 55 knot low level jet across eastern Arkansas moved into western Kentucky during the evening, resulting in isolated tornadoes and widespread damaging winds.

The tornado moved northeast across Mound City, where much of the damage occurred. One small mobile home was picked up and thrown into a power pole. There was roof damage to several homes, mainly shingles. Numerous trees were uprooted and snapped. The tornado damage path ended at the Ohio River. Peak winds were estimated near 105 mph. The average path width was 200 yards.

Mainly tree damage was observed. Some trees were uprooted and snapped. One small shed was damaged. There was minor damage to business roofs in Pulaski. Some straight-line wind damage was observed on the southeast end of the path. Peak winds were estimated near 90 mph. The average path width was 100 yards.

The tornado gained strength after crossing into Massac County from Pulaski County. North of the Mermet Lake Conservation Area, the tornado reached peak intensity. A barn was destroyed, and debris was thrown several hundred yards. Two grain bins were destroyed, including one that was thrown over 265 yards. Other small outbuildings were destroyed. There was minor to moderate damage to four homes from falling trees and strong winds. As the tornado moved northeast, it damaged a house near the Massac/Johnson County line. The back porch was ripped off. Trees were snapped and thrown into a vehicle and garage. There was roof, siding, soffit, and shutter damage to the home as well. In a nearby field, an irrigation system was overturned. The tornado funnel was photographed from a residence near Round Knob. Peak winds were estimated near 115 mph. The average path width was 300 yards. The tornado continued northeast into Johnson County.

The tornado crossed into Johnson County from Massac County in the vicinity of Interstate 24. A barn was destroyed just before where the tornado crossed Interstate 24. Significant tree damage was observed near the community of Ganntown, where trees were snapped and uprooted and a home had minor damage. The metal roof of the house was damaged. On the west side of Grantsburg, a 20-by-50 foot pole barn was destroyed, and swirls were seen in tall grass. Near the end of the damage path in the Shawnee National Forest, over 100 trees were snapped or uprooted. Peak winds were estimated near 100 mph. The average path width was 150 yards.

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

12 minutes of warning. NWS PAH issued a tornado warning for this county at 23:43 UTC, 12 minutes before the tornado touched down, in force until 00:15 UTC.

The county was under a tornado watch, issued at 16:14 UTC and running to 01:37 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 0.30 chance of a tornado within 25 miles, in the hatched area where significant tornadoes were expected. The outlook in force was issued at 19:39 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.

Metropolis IL (M30), 17 km from the path, in the two hours either side.

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

The Paducah radar (KPAH), 28 km away, was scanning. The volume nearest the touchdown began at 23:55 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 2011 tornado in IllinoisEvery tornado in Illinois since 1950Warnings in force in Illinois nowThe forecast where you are

93 more were confirmed in the United States that day.

All 94 of them

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.