EF0 tornado, Union to Crystal, North Dakota, August 26, 2007

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

August 26, 2007

Touchdown

6:55 PM CDT (23:55 UTC)

Lifted

7:05 PM CDT (00:05 UTC)

On the ground

10 minutes

Path length

5.0 miles (8.0 km)

Path width

30 yards (27 m)

Deaths

0

Injuries

0

Counties

Pembina and Cavalier counties

Touchdown point

48.550, -97.996

Lift-off point

48.572, -97.900

Record number

0708261755-01

A cold front moved across North Dakota on the 26th, with a hot and humid airmass in place ahead of the front. At 6 pm CST, a surface low was located over southern Manitoba (Canada), just north of Pembina, ND. The cold front stretched to the southwest, back toward Devils Lake (ND) and Bismarck (ND). Ahead of the cold front, temperatures ranged in the low to mid 80s with dew points around 70F. Behind the front, temperatures did not cool significantly, but dew points dropped to the mid 40s. Thunderstorms began to form along and ahead of the cold front by early evening (from northeast ND into south central ND), eventually crossing into northwest Minnesota several hours later. Eight distinct tornadoes occurred over northeast North Dakota and northwest Minnesota during this event.

This tornado tracked intermittently to the east-northeast and passed about a mile north of Union. The tornado then crossed into Pembina County, where it dissipated one mile southwest of Garder at 605 pm CST. The tornado had a total path length of 5 miles, and 4 miles of the total occurred in Cavalier County. No damage was reported. The highly visible funnel and its intermittent contact were viewed and reported by several spotters in Pembina and Walsh Counties. Peak winds were estimated at 70 mph.

This tornado originated 3 miles west of Union (in Cavalier County) at 555 pm CST. It crossed into Pembina County about 1 mile northeast of Milton. The tornado produced no damage, as it remained in rural farm fields. The total path length was 5 miles, but only about 1 mile occurred in Pembina County. The funnel and intermittent contact was viewed by spotters in Pembina and Walsh Counties at distances of 5 to 15 miles away. Peak winds were estimated at 70 mph.

After the first tornado tracked from near Union (Cavalier County) to near Garder (Pembina County), a second tornado was produced by the same parent supercell thunderstorm. This tornado touched down about 5 miles west-southwest of Crystal (Pembina County) and continued to about 1.5 miles west of Hoople (Walsh County). The total tornado track was about 5 miles, and about 3 miles of the track occurred in Pembina County. The tornado made numerous strikes in shelterbelts 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.

3 minutes of warning. NWS FGF issued a tornado warning for this county at 23:52 UTC, 3 minutes before the tornado touched down, in force until 00:22 UTC.

The county was under a tornado watch, issued at 22:10 UTC and running to 01:51 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 19:58 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), 124 km away, was scanning. The volume nearest the touchdown began at 23:54 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 2007 tornado in North DakotaEvery tornado in North Dakota since 1950Warnings in force in North Dakota nowThe forecast where you are

10 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.