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EF1 tornado in Ransom County, North Dakota

Tornado July 15, 2007 · Ransom County, North Dakota

EF1
Rating
10.0 mi
Whole path
200 yd
Path width
$500K
Damage as recorded

NOAA records this tornado county by county. Its path ran through Cass County → Ransom County; the totals above are for the whole tornado.

EF0EF1EF2EF3EF4EF5Unrated

The path drawn at its surveyed width of 200 yards (0.11 mi) — zoom in and the swath grows to true scale. Other tornadoes recorded nearby that day are shown faint.

What EF1 means. On the Enhanced Fujita scale, EF1 is moderate damage: roofs badly stripped, mobile homes pushed off foundations or overturned, windows broken, consistent with estimated gusts of 86–110 mph. The rating comes from a survey of the worst damage after the storm, not from a wind measurement, so it says as much about what the tornado hit as about how strong it was.

What the National Weather Service wrote

This tornado began in Cass County at 625 pm CST. The tornado yanked one aluminum high voltage power tower out of its steel footings and toppled several others. It also snapped several wooden power poles at multiple road crossings across its path. Peak winds were estimated at 105 mph.

The wider storm

At 3 pm CST on the 15th, a stationary front was located from near Minot (ND) to Jamestown (ND) to near Sisseton (SD). South of the front, mid afternoon temperatures ranged in the mid 80s to lower 90s. To the north of the front, a meso-high had formed, with much cooler and drier air around it. The temperature across the boundary ranged from 89F at Minot, to 73F at Devils Lake, to 64F at Crookston. The upper air pattern had a western ridge and an eastern trough, putting the northern plains in northwest flow aloft. A strengthening upper jet also moved toward eastern North Dakota, giving this system good surface and upper level support.

A supercell thunderstorm developed over southern Steele County around 530 pm CST and tracked across western Cass County and into eastern Ransom County before weakening after 7 pm CST. Then, another supercell thunderstorm formed over northern Steele County around 725 pm CST. This storm tracked just west of the path of the first storm, again mainly hitting central Steele County, western Cass County, and eastern Ransom County, before weakening around 915 pm CST. Both thunderstorms tracked south-southeast at speeds between 40 and 50 mph and spawned multiple tornadoes which were embedded within the overall downburst wind and hail pattern.

The significant downburst wind and wind driven hail was seen in two partially overlapping paths, with each path from 5 to 7 miles wide and between 60 and 80 miles long (this damage path showed up clearly on satellite images). The strength of these winds is believed to have exceeded 80 mph with speeds over 100 mph in some localized areas. Hail sizes ranged from penny to hen egg sized.

Most areas received considerable hail damage at the same time as the strong winds. Law enforcement officials and witnesses stated that the hail often persisted for longer than 5 minutes and completely covered the ground. The hail damaged roofs, windows, and siding in many homes along the damage path. Stripped and decimated corn, bean, and wheat fields were typical along the entire storm path too. The ND Farm Service Administration estimated losses occurred on over 700,000 acres in five counties. Total crop losses may exceed $250 million, with other property losses from $15 to $20 million. Cass and Steele Counties received a Presidential Disaster Declaration.

Began near Sheldon (46.6413, -97.3907).

Other tornadoes from the same storm system

4 more tornadoes the National Weather Service filed under this storm episode.

Source: NOAA Storm Events Database, event 48309. Narratives are written by the National Weather Service forecast office that issued the report.

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