EF-scale for concrete silos?
Hello, I've been skimming through the very long pdf file for damage that the NWS makes available and it's unclear to me what would be equivalent to a "concrete silo" on the scale. Since major destruction of institutional concrete structure lowbound is 178 and expected is 210 and upbound is 268, I suppose that the concrete construction of a silo must be very shoddy in comparison to come up with the figure of 160 to have "cleanly snapped off two concrete silos"? This is regarding the second major incarnation of the Parkersburg wedge that was rated an EF-3 rather than an EF-5. Is a warehouse building (131/158/186 for destruction of large section) (page 79) closer to what a concrete silo is as of now considered? Or was that factor not really integrated because not enough study yet on concrete silos, I notice on page 19 of the EFscale.pdf document, this:" Research is currently underway to identify additional damage indicators and to obtain estimates of the wind speeds to cause defined damage. Of particular interest are damage to various crops, farm equipment, silos, grain storage facilities and irrigation equipment. These indicators can be incorporated as DIs in the EF Scale as reliable data become available."
Anyway, here' s the news article:
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Article published: May 27, 2008
Tracking of tornadoes saved lives in Hazleton
HAZLETON This town would be a blank spot on the map if the tornado that struck it Sunday evening had hit it dead center, Buchanan County Sheriff Bill Wolfgram said.
As it was, the tornado that hit the town's south edge destroyed more than 10 homes and damaged more than 40 others, according to Hazleton Mayor Roger Carson. It also destroyed 50 of the 56 homes on the lot of Horkheimer Custom Factory Built homes, as well as several buildings and semi tractor-trailer rigs at Paul Michels' trucking company, both on the south edge of Hazleton,
The tornado, believed to be a continuation of the one that killed four people in Parkersburg and two in New Hartford, struck at 6:15 p.m.
"It was huge and black," said Assistant Hazleton Fire Chief Mike Foland, who activated the town's outdoor alert siren about three to five minutes before it struck.
Jerry Horkheimer, proprietor of the 40-year-old modular home business, said the storm left him with little to salvage.
Across a field strewn with shattered bits of 50 modular homes, Horkheimer's friend, Paul Michels, directed the cleanup Monday of his obliterated home and trucking business.
Michels, who rode out the storm in a grease pit beneath his truck maintenance shed, said he lost his house, maintenance shed, three grain bins and at least four semi-tractors and six trailers.
Tragic as they were, the tornadoes that hit Parkersburg and New Hartford, both in Butler County, generated media coverage that probably saved lives in Black Hawk and Buchanan counties, according to the counties' emergency management coordinators.
"The forewarning was huge. Their tragedy gave us the heads up we needed to take shelter and avoid injuries," said Buchanan County Emergency Management Director Rick Wulfekuhle, who estimated that the tornado damaged at least 100 homes in the county, along with comparable numbers of farm outbuildings and vehicles.
The path of the storm could be easily traced Monday by the fresh white scars of snapped-off trees and the trail of debris littering freshly planted crop fields.
The tornado traveled east from Hazleton, destroying several homes and farmsteads along County Road C57, including the home of Dean and Angela Tournier, who took shelter with their two daughters in the basement.
"It was a massive wall of black with flying stuff coming at you. It was so wide you couldn't see the edges. It didn't look like a tornado," Angela Tournier said.
Dean Tournier said the tornado picked up the family horse and put it down half a mile away. "The horse was banged up but basically OK," he said.
Tournier himself was banged up enough to require treatment for cuts and bruises at Mercy Hospital in Oelwein.
The storm seemed to rage for at least five minutes "with stuff flying and banging overhead," while he and his family huddled in the basement, Tournier said.
Farther east on 130th Street, the tornado destroyed a dairy barn and cleanly snapped off two concrete silos at the home of Dan and Diane Sperfslage.
Darryl and Becky Wunder were hosting a party at their 130th Street acreage when Darryl Wunder saw "this black wall coming" and told everyone "to hit the basement."
"We could hear windows breaking and trees cracking," said Becky Wunder, 54, whose family home was destroyed by a tornado 40 years ago in Oelwein. Darryl Wunder estimated damage to their home at $100,000. "We're stubborn. We'll stay in it while we fix it up," Becky Wunder said.
Marc Russell, a meteorologist with the National Weather Service in Des Moines, said last night that the tornado that traveled through Butler, Black Hawk and Buchanan counties was "basically one super cell that may have had some satellite tornadoes."
An assessment team that spent Monday in the area will return today to finish its work, he said.
The tornado was accompanied by heavy rains ranging from 5 to 7 inches along its course.
Flash flooding damaged roads and bridges and caused extensive soil erosion and damage to recently planted crop fields.
Flooding also forced the closure Monday of Backbone State Park near Dundee in Delaware County.
Backbone Park Ranger Dave Sunne estimated that more than half of the park was under water Monday afternoon. The park also will be without electricity for at least the next two to three days, he said.
Scores of crews worked Monday in Buchanan County to replace utility poles snapped off by the tornado.
Worth A Look
According to the National Weather Service two tornadoes hit Buchanan and Delaware counties on Sunday.
Here are the preliminary reports from survey crews on each.
The first tornado:
went on a 32.4 mile line from near Fairbank to near Oneida.
struck during an approximately 65-minute time period from 6:05 p.m. to 7:10 p.m.
injured three people.
had an estimated wind speed of about 160 miles per hour.
was about 0.7 miles wide.
had and intensity consistent with an EF3 tornado.
destroyed three homes, numerous farmsteads and outbuildings, trees and power poles. Many homes had roof damage. Several non-anchored mobiles homes at a dealership near Hazelton were destroyed.
The second tornado:
went on a 6 mile line in Delaware County south of Petersburg for about 10 minutes between 7:30 p.m. and 7:40 p.m.
caused no injuries.
was approximately 250 yards wide
had an intensity of an EF1 tornado.
damaged trees and numerous farm outbuildings.