EF0 tornado, Ambrose, North Dakota, May 22, 2012

1. EF065 to 85 mphthis tornado

   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 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

EF0

Date

May 22, 2012

Touchdown

5:07 PM CDT (22:07 UTC)

Lifted

5:17 PM CDT (22:17 UTC)

On the ground

10 minutes

Path length

5.3 miles (8.6 km)

Path width

50 yards (46 m)

Deaths

0

Injuries

0

County

Divide County

Touchdown point

48.983, -103.592

Lift-off point

48.998, -103.477

Record number

1205221607-01

Tornado Watch number 290 and Severe Thunderstorm Watch number 291 were in effect during this event. ||Strong afternoon destabilization occurred north and east of an area of low pressure situated over southwest North Dakota May 22nd. The trigger for thunderstorm development was a strong upper level jet streak advecting northeast across the Rockies and into the Northern Plains. While a strong capping inversion was in place in the low's warm sector, a weaker cap existed over northern North Dakota, where convection first initiated late in the afternoon over the far northwest. Additional strong to severe thunderstorms developed during the evening across the north central and from the south central into the James River Basin. Severe hail, severe thunderstorm winds, and two confirmed EF0 tornadoes occurred during this event.

This tornado touched down in the open country of Divide County, along the international border. There were no reports of damage associated with this tornado.

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

No tornado warning for this county appears in the archive as in force at the moment the tornado touched down.

The county was under a tornado watch, issued at 21:05 UTC and running to 23:41 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 19:57 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.

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 2012 tornado in North DakotaEvery tornado in North Dakota since 1950Warnings in force in North Dakota nowThe forecast where you are

1 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.