Storm Damage Survey of Sunday, July 15, 2007

Public Information Statement on event
Hi-Resolution Satellite Map Shows Damage

An NWS storm damage survey team examined portions of southeast North Dakota which were hit with severe thunderstorms on Sunday evening, July 15th. 2007.  The travel path began in Finley and extended through the towns of Hope, Colgate, Page, Buffalo, Tower City , Embden, Sheldon, Alice, through portions of the Sheyenne National Grasslands, and to McLeod.  The storm damage assessment has confirmed that two consecutive and powerful supercell thunderstorms traversed this area and spawned multiple tornadoes which were embedded within the overall downburst wind and hail pattern. 

These thunderstorms tracked south-southeast at speeds between 40 and 50 miles per hour, beginning in Steele county, and maintained strength as they traveled through western Cass county and eastern Ransom county.  The first storm followed this path from 6:30 p.m. through approximately 8:00 p.m.  The second storm moved along a path just to the west of the first storm from 8:45 p.m. through 10:15 p.m.  Most of the area received widespread damage from downburst winds, hail, and the several tornado touchdowns.  (see the Hi-Resolution Satellite Map of damage)  

The storm damage survey team established that five tornadoes occurred throughout Cass and Ransom County between 7:15 p.m. and 9:30 p.m.  The tornadoes were declared as a combination of EF1 and EF2 ratings with peak winds between 105 and 130 miles per hour.  Extreme tree, building, and power pole damage within several narrow paths was well correlated with rotation evident on Doppler weather radar and funnel cloud sightings from storm spotters.  Although significant damage was evident through much of the southeastern portion of the state, these tornadoes were associated with the more extreme damage and with debris which was often carried tens to hundreds of yards downstream.  The extreme damage track and debris spread were also oriented differently from the dominant downburst wind pattern.  

Significant downburst wind damage was seen in two partially overlapping paths, with each path from five to seven miles wide and between 60 and 80 miles long.  The strength of these winds is believed to have exceeded 80 miles per hour with speeds over 100 miles per hour in some localized areas.  These downburst winds broke numerous large tree branches, snapped full grown tree trunks, and even uprooted many large trees.  Structural damage along the storm path included roof, door and siding damage to a hundred or more farm outbuildings; dozens of smaller yard sheds tumbled or crushed; numerous dented grain storage bins; field irrigation systems  overturned; a few homes with significant roof, rafter and shingle damage; and extensive damage to several parks, ball fields, and recreation areas.   Hail and wind damage to insured and uninsured structures at the farms and communities along the storm paths could be in the $1-10 Million range (rough estimate only!). 

Throughout the duration of these storms, numerous wooden power poles and metal high voltage power towers were snapped or crumpled.  Although most of these towers were blown over as a result of strong downdraft winds, south of Embden there was a high voltage electrical tower pulled out of its anchor system and laid down horizontally indicating the possibility of significant updraft winds.  There were 60  steel or aluminum, high voltage power towers and 8 double pole, wooden, high voltage power poles destroyed in three counties.  The number of local distribution, singlular wooden power poles which were snapped off is still untotalled, though all of these were repaired in short order.  Total losses to the electrical system could be in the $3-5 Million range (rough estimate only!)

Most areas received widespread wind damage along with considerable hail damage along paths two to five miles wide.  Hail ranged in size from one half inch to two inches in diameter and was often accompanied by winds in excess of 60 miles per hour.  Several law enforcement officials and witnesses stated that hail often persisted for longer than five minutes and completely covered the ground.  Significant damage occurred due to the hail accompanied by strong winds including many homes with broken windows and siding.  Stripped and decimated corn, bean , and wheat fields were a common sight throughout the entire path of the thunderstorms.  The ND Farm Service Administration estimates that losses occurred on over 700,000 acres in five counties.  Total crop losses could easily exceed $100-200 Million (rough estimate only!).   

Photo Archive:

This 360,000 bushel grain bin in Finley, ND was dented in due to the high downburst winds.

Figure 1:  This 360,000 bushel grain bin in Finley, ND was dented in due to the high downburst winds.

 

A farmstead two miles south of Finley received significant damage to trees, windows, and their garden shed.

Figure 2:  A farmstead two miles south of Finley received significant damage to trees, windows, and their garden shed.  Fortunately the kittens were okay!

An irrigation system near Colgate, ND was overturned out in an open field.

Figure 3:  An irrigation system near Colgate, ND was overturned out in an open field.

 

 

Figure 4:  On a farmstead two miles west of Buffalo, ND , a grain bin and barn door suffered significant damage.

Roof damage in Tower City and its accompanying debris field indicated the possibility of a brief tornado touchdown.

Figure 5:  Roof damage in Tower City and its accompanying debris field indicated the possibility of a brief tornado touchdown.

 

 This garage in Tower City was lifted and flattened to the ground along with many snapped and uprooted large trees.

Figure 6:  This garage in Tower City was lifted and tossed to the ground along with many snapped and uprooted large trees.

Stripped and snapped cornfields were a common sight throughout the entire path of the thunderstorms.

Figure 7:  Stripped and decimated corn, bean , and wheat fields were a common sight throughout the entire path of the thunderstorms.  The ND Farm Service Administration estimates that losses occurred on over 700,000 acres in five counties.  Total crop losses could easily exceed $100-200 Million (rough estimate only!).

 

 This Minnkota Power tower was one of the nine towers damaged seven miles south of Embden.

Figure 8:  This Minnkota Power tower was one of the nine towers damaged seven miles south of Embden.  There were 60  steel or aluminum, high voltage power towers and 8 double pole, wooden, high voltage power poles destroyed in three counties.  The number of local distribution, singlular wooden power poles which were snapped off is still untotalled, though all of these were repaired in short order.  Total losses to the electrical system could be in the $3-5 Million range (rough estimate only!)

This three car garage south of Buffalo was lifted and thrown backwards off its concrete slab.

Figure 9:  This three car garage south of Buffalo was lifted and thrown backwards off its concrete slab. 

 

 This barn was lifted and portions of it were thrown against structures to its south.

Figure 10:  This barn was lifted and portions of it were thrown against structures to its south.  Debris from these buildings was also blown to the east.

Here, a wooden barn southeast of Tower  City was blown over while dozens of large trees were uprooted.

Figure 11:  Here, a wooden barn southeast of Tower City was blown over while dozens of large trees were uprooted.  And don't forget hail - virtually all these farmsites and communities were affected by significant wind driven hail.  

 

 Numerous structures such as this received roof, door, or siding damage as high winds and hail buffeted the region.

Figure 12:  Numerous structures such as this received roof, door, or siding damage as high winds and hail buffeted the region.  Hail and wind damage to insured and uninsured structures at the farms and communities along the storm paths could range in the $1-10 Million (rough estimate only!). 


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