EF1 tornado, New Salem to Sweet Briar, North Dakota, May 24, 2008

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

May 24, 2008

Touchdown

8:10 PM CDT (01:10 UTC)

Lifted

8:25 PM CDT (01:25 UTC)

On the ground

15 minutes

Path length

5.5 miles (8.9 km)

Path width

75 yards (69 m)

Deaths

0

Injuries

0

Property damage

$200,000

County

Morton County

Touchdown point

46.770, -101.469

Lift-off point

46.850, -101.462

Record number

0805241910-01

In the late afternoon of May 24th, Tornado Watch 352 was issued in anticipation of severe thunderstorms and possible tornadoes developing along and ahead of a strong closed upper level low and associated surface low and cold frontal boundary over southern North Dakota. Numerous severe thunderstorm warnings and tornado warnings were issued. Reports included multiple tornadoes in both Morton and Dickey counties. A National Weather Service storm damage survey was completed in Morton County, and the Dickey County Emergency Manager conducted a storm damage survey in Dickey County.

The tornado was originally reported by Morton County law enforcement. A storm damage survey was conducted by the National Weather Service and found that damage occurred to five farms in the New Salem area. Damage to farm houses was minor. Damage to farm outbuildings was significant with roofs torn off and smaller buildings destroyed. In some cases small outbuildings were destroyed while others nearby had little in any damage. Horse trailers were pushed and some were tipped. Tree trunks were snapped part way up their bases. The tornado damage corresponded to EF1 on the Enhanced Fujita Scale. From that it was determined that wind speeds in the tornado were on the order of 100 mph. This was the first of two tornadoes in Morton County this evening.

The National Weather Service conducted a storm damage survey in Morton County. With this tornado there was no evidence of damage. The tornado stayed over open areas. Traffic on Interstate 94 stopped as the tornado crossed the highway. This was the second tornado in Morton County this evening. An EF scale rating of EF0 was assigned with estimated wind speeds around 65 mph.

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

7 minutes of warning. NWS BIS issued a tornado warning for this county at 01:03 UTC, 7 minutes before the tornado touched down, in force until 01:30 UTC.

The county was under a tornado watch, issued at 23:25 UTC and running to 04:36 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 0.05 chance of a tornado within 25 miles. The outlook in force was issued at 01:04 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 Bismarck radar (KBIS), 54 km away, was scanning. The volume nearest the touchdown began at 01:10 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 2008 tornado in North DakotaEvery tornado in North Dakota since 1950Warnings in force in North Dakota nowThe forecast where you are

22 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.