EF1 tornado, Buffalo to Monticello, Minnesota, June 17, 2010

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 mphthis tornado

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

3. EF2111 to 135 mph

   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

EF1

Date

June 17, 2010

Touchdown

6:00 PM CDT (23:00 UTC)

Lifted

6:08 PM CDT (23:08 UTC)

On the ground

8 minutes

Path length

5.1 miles (8.3 km)

Path width

50 yards (46 m)

Deaths

0

Injuries

0

County

Wright County

Touchdown point

45.201, -93.868

Lift-off point

45.272, -93.838

Record number

1006171700-02

Several strong storms developed in west-central Minnesota during the mid afternoon hours of June 17th. ||These storms quickly become severe and produced softball size hail northwest of Alexandria and a tornado near Leaf Valley that became the EF-4 that moved through Wadena, Minnesota. ||By the late afternoon, numerous thunderstorms developed across southern Minnesota along the leading edge of extreme instability. ||Numerous funnel cloud reports and a few brief tornado touchdowns were noted prior to 5 pm, but once the low level shear (0-1 km) increased significantly from 15 knots, to over 35 knots, strong tornadoes developed along the Iowa border.| |These storms along the Iowa border produced a series of long-lived tornadoes near Albert Lea, Minnesota. Very large hail also accompanied some tornadoes along with flash flooding.

Isolated tree damage was noted near the initial touchdown location, but the damage became more concentrated and more intense as the storm approached Constance Lake. Low end EF-1 tornado damage was noted, as the trunks of several trees were snapped at locations on both sides of the lake. An intermittent damage path continued further north, with damage to trees and a small lean-to shelter. The tornado dissipated near the intersection of 85th St NE and Cahill Ave.

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

32 minutes of warning. NWS MPX issued a tornado warning for this county at 22:28 UTC, 32 minutes before the tornado touched down, in force until 23:15 UTC.

The county was under a tornado watch, issued at 18:54 UTC and running to 02:00 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 Moderate Risk, with a 0.10 chance of a tornado within 25 miles, in the hatched area where significant tornadoes were expected. The outlook in force was issued at 20:06 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.

Buffalo (CFE), 9 km from the path, in the two hours either side.

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

The Minneapolis radar (KMPX), 49 km away, was scanning. The volume nearest the touchdown began at 23:01 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 2010 tornado in MinnesotaEvery tornado in Minnesota since 1950Warnings in force in Minnesota nowThe forecast where you are

73 more were confirmed in the United States that day.

All 74 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.