EF1 tornado, Forest River to Warsaw, North Dakota, June 26, 2009

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 26, 2009

Touchdown

6:35 PM CDT (23:35 UTC)

Lifted

6:42 PM CDT (23:42 UTC)

On the ground

7 minutes

Path length

3.1 miles (4.9 km)

Path width

300 yards (274 m)

Deaths

0

Injuries

0

Property damage

$250,000

Crop damage

$50,000

County

Walsh County

Touchdown point

48.382, -97.416

Lift-off point

48.402, -97.356

Record number

0906261735-01

A warm front pushed northward through eastern North Dakota during the afternoon of the 26th. By the early evening, low pressure had set up over northwest South Dakota, with the warm front extending to the northeast along a line from near Bismarck to near Devils Lake. The airmass in the warm sector was quite juicy, with surface dew points in the mid to upper 60s and temperatures in the low 90s. Thunderstorms fired up along the front and moved very slowly, which led to heavy rainfall and some flooding issues. Atmospheric conditions were also favorable for tornadoes, with the warm front, juicy air, and outflow boundaries from the thunderstorms. This led to a large number of funnel cloud reports, mostly because the rotating low clouds advanced through the larger population density centered around the Grand Forks/East Grand Forks area.

From near Forest River, a tornado tracked east-southeast to about 1.5 miles southwest of Ardoch. The tornado broke down several large tree limbs in shelterbelts and produced a fairly wide debris swirl to the west of Ardoch, as viewed by observers near the southwest edge of Ardoch. Peak winds were estimated at 80 mph.

The tornado lifted a barn from its foundation and destroyed it while uprooting numerous trees in the farmyard. Later the tornado broke down three power poles and snapped off numerous other trees along its route. Peak winds were estimated to 105 mph.

The tornado snapped off numerous large tree limbs and blew down a 3000 bushel steel grain bin along its path. Peak winds were estimated at 90 mph.

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

39 minutes of warning. NWS FGF issued a tornado warning for this county at 22:56 UTC, 39 minutes before the tornado touched down, in force until 00:00 UTC.

The county was under a severe thunderstorm watch, issued at 19:53 UTC and running to 23:44 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 Slight Risk, with a 0.02 chance of a tornado within 25 miles. The outlook in force was issued at 20:02 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.

The Fargo/Grand Forks radar (KMVX), 96 km away, was scanning. The volume nearest the touchdown began at 23:34 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 2009 tornado in North DakotaEvery tornado in North Dakota since 1950Warnings in force in North Dakota nowThe forecast where you are

18 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.