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El Paso county, 28 May 2001 1. Summary During Monday evening (Memorial Day) 28 May 2001, a very severe thunderstorm impacted the Ellicott area, which is 23 miles east of downtown Colorado Springs. A Tornado Watch was in effect for the area until 10:00 p.m. Thunderstorms began to develop from Fountain to Ellicott before 6:00 p.m. MDT. Episodes of hail occurred in the Ellicott area, ranging from pea to golf ball size between 5:30 p.m. and 9:50 p.m. The hail piled up several inches deep from a few miles south of Ellicott to around 3 miles north and northeast of Ellicott. Winds gusted over 60 mph over a wide area around Ellicott during that same time. After a thunderstorm cell merger, and between 7:20 p.m. and 7:25 p.m. a mesocyclone between 3 and 4 miles in diameter intensified. Video evidence was invaluable in determining the following. Between approximately 7:23 p.m. and 7:28 p.m. extreme straight-line winds, consisting of some twisting microbursts, rated F1 to F2 (low F2) blew from the east-southeast and east, damaging and destroying around 70 mobile homes. Winds are estimated between 75 mph and 120 mph. Embedded within the extreme straight-line winds were three narrow tornadoes with short damage paths. One tornado, rated F2 (low F2), struck a mobile home park located one mile west-northwest of the intersection of Ellicott Highway and Highway 94 just east of Log Road. Four mobile homes were destroyed, and several more were damaged in that mobile home park. Another tornado, rated F1 struck a mobile home and flipped it over about ½ mile south of Highway 94 on Log Road. Another tornado developed about 200 yards southeast of the Ellicott Junior-Senior High School building (located about 3/4 of a mile south of the intersection of Ellicott Highway and Highway 94), rated F2 (high F2), and did severe damage to the building. Extreme straight-line winds from the east-southeast, consisting of some twisting microbursts, damaged or destroyed over 50 mobile homes from about 1 3/4 miles to one mile south-southeast of the intersection of Ellicott Highway and Highway 94. Nineteen persons were injured, mostly those who were in mobile homes which flipped over or rolled. The worst injury was a broken leg. During the morning and early afternoon of 29 May, and again during the
morning of 30 May representatives from the National Weather Service (NWS)
conducted surveys of damage. The purpose of the survey was: a) to determine, as closely as possible, the magnitude and areal extent
of the damage, and b) to evaluate whether the damage was caused by straight-line winds
or tornadoes.
2. Survey team Survey team members included the Warning Coordination Meteorologist, a Lead
Forecaster, and an SCEP student, all from WFO Pueblo, Colorado.
3. Summary of damage and specific damage locations Survey team members determined that a 3/4 mile wide area of F0 to F2 damage, which occurred between about 7:23 p.m. and 7:25 p.m. extended from around 2 miles to 1 1/4 miles south-southeast of the intersection of Ellicott Highway and Highway 94. This was likely due to extreme straight-line winds, consisting of some twisting microbursts, blowing from the east-southeast up to around 120 mph. Several mobile homes were rolled over, and occupants sustained minor injuries. Other residences and vehicles in the area sustained damage too numerous to mention individually. It appeared that vehicles that were on the scene at the time of the event did NOT move or moved very little. Two of the mobile homes rolled on top of two vehicles, partially crushing them, trapping one man inside his car for 30 minutes. The F2 tornado which struck the junior-senior high school building occurred from approximately 7:25 p.m. to 7:26 p.m. The tornado path length was about ½ mile long, extending from around 200 yards east-southeast of the Ellicott Junior-Senior high school building (3/4 of a mile south of the intersection of Ellicott Highway and Highway 94), between that building and a new school under construction to the south, and then another 500 yards west-northwest into a pasture. The tornado moved west-northwest. Maximum path width was around 200 yards. Video showed two intertwined (braided) funnels. The damage along the path was rated from F2 to F1. The F2 damage (high F2 with winds around 150 mph) occurred on the southwest and west side of the Ellicott Junior-Senior High School building. Evidence suggests that a red dumpster (which rested about 400 yards west-northwest of the building) and a modular trailer used for a classroom (the frame found just south of the building), originally on the south side of the main school building, became airborne and struck the south side of the Junior-Senior High School building. Another red dumpster also hit the building and came to rest next to a shattered section of brick wall. Another blue dumpster (25 x 6 x 6 feet) also may have hit the building, arriving from around 150 yards away at the construction site of the new school building. These missiles caused catastrophic failures of the Junior-Senior High School’s south brick and metal framed wall. The wind entered the southwest side of the building which caused a catastrophic failure of the large “free-span” corrugated metal roof. An eyewitness said the southwest portion of the school building looked like it exploded. The roof was found rolled up in several large sections, from around 60 to 200 feet long and 15 to 20 feet high. The farthest rolled up section of roof rested about 500 yards west-northwest of the school building in an open field. A structure around 20 yards south of the school building sustained F2 damage. The roof and parts of the south and west wall failed and the entire north wall failed. This structure may have been hit by the blue dumpster after the blue dumpster had hit the school and curled on back to the south. There were two vehicles on the west side of the school building. One of the vehicles, a Ford Taurus, was in the parking lot and was damaged by small pieces of debris. This vehicle did NOT move or moved very little. Apparently, the roof narrowly missed this vehicle and hit a nearby flag pole and small red truck in the parking lot. The flag pole was bent down at an 80 degree angle. The small red truck, just to the north of the Taurus, was heavily damaged and was rolled around 40 feet to the west-northwest. A preliminary damage estimate to the Junior-Senior High School building and the new school under construction is $8 million. An F1 tornado occurred just east of South Log Road, about ½ mile south of Ellicott Highway, nearly simultaneously with the F2 tornado that hit the schools. It moved west and its path length was approximately 1/10 of a mile long and 30 yards wide. An occupied mobile home was flipped over, but there was little debris scatter. The occupants received minor injuries. Two vehicles on blocks adjacent to the mobile home did NOT move. This tornado lifted over an open field west of Log Road. At approximately 7:28 p.m. a brief tornado and twisting microburst did damage in a mobile home park around one mile west-northwest of the intersection of Ellicott Highway and Highway 94 just east of Log Road. The F2 tornado path length was around 1/3 mile long and 30 yards wide. The tornado traveled west. Severe damage to mobile homes (which were struck broadside) and power poles occurred along the path, and F0 to F1 damage occurred approximately 100 yards to the north of the tornado path due to a twisting microburst. One mobile home was thrown up onto the roof of an adjacent mobile home. All occupants escaped with minor injuries. Another mobile home was flipped over with five occupants; a mother, two infants, a child, and a deaf and blind woman. None were seriously injured. This mobile home, as were most in the Ellicott area, was anchored with 4" auger-type metal stakes which were screwed into the ground with little, if any concrete support. Another mobile home to the west was not anchored down and was rolled over 100 feet across Log Road. There was very little debris scatter from the mobile homes. It was observed that all vehicles next to the mobile homes that were flipped over did NOT move. Mobile homes, primarily on the north side of the tornado path, sustained broken windows and roof and siding damage due to flying debris and hail. A few of these mobile homes were partially pushed off their blocks. Sheet metal from outbuildings and other light-weight materials were scattered up to 500 yards west of Log Road in an open field. Damage to more permanent residences was mainly restricted to broken windows (mainly from the large hail), roofs partially ripped off, shingles ripped off, metal or aluminum siding or roofs dented by hail, and paint stripped off wooden siding by the hail. Individual report of damage to homes, businesses, outbuildings, vehicles,
trees, shrubs, windows, fences, signs, and power lines are too numerous
to include in this report individually.
4. Mesoscale and misoscale meteorology of the event The severe cell remained nearly stationary over Ellicott for over an
hour and dumped heavy rain, large quantities of large hail, and occasional
damaging wind gusts from the east and southeast. Between 7:00 p.m.
and 7:20 p.m. another storm cell moved east-northeast and collided with
the Ellicott storm. This cell merger further intensified the storm
and its large mesocyclone. A band of severe wind gusts, consisting
of some twisting microbursts, from the east-southeast south of Highway
94 and from the east north of Highway 94 developed on the east side
of the mesocyclone. The winds maximized in the three brief tornadoes:
near the school buildings, in the mobile home park west-northwest of Ellicott,
and on South Log Road. Video
(see
video) evidence shows the likelihood of three
tornadoes, the school building tornado consisting of two braided funnels
for a time. The rest of the damage was F0 to F2, and
was likely caused by straight-line winds, some twisting microbursts. Below
is a doppler radar image of the high precipitation supercell, showing a large
hook on the southwest side. Ellicott is just to the right of the hook.
5. Eyewitnesses The survey team conducted person interviews with many people who were
in the area during the events. Eyewitness reports from the media
and emergency officials were also considered. Many reported hearing
loud noise and seeing twirling debris. Loud noise can occur with
both extreme straight-line winds and tornadoes. Twirling debris can
also occur with either turbulent extreme straight-line winds or tornadoes.
The eyewitness, who saw the junior-high school building disintegrate, reported
seeing a small funnel-shaped cloud on the ground. Another eyewitness
and video from a storm chaser confirm that two funnels were intertwined
in the vicinity of the school buildings.
6. Watch, Warnings, and Statements The Tornado Watch and all warnings and statements issued by WFO Pueblo,
pertaining to the Ellicott storm, are listed in Table 1 below. The
initial SVR (severe thunderstorm warning) mentioned the most likely kinds
of severe weather were hail around one inch in diameter and winds around
60 mph. The severe hail reports began coming into WFO Pueblo 17 minutes
after the initial warning was issued. The TOR (tornado warning) was
issued at 7:26 p.m., nearly concurrent and shortly before the touchdowns.
TABLE 1. Watch, Warnings and Statements issued between 2:00 p.m. and 8:49 p.m. 28 May 2001. All times are MDT. Type Valid time Significant Weather Outlook 700 AM - Midnight
Public Information Statement 10:08 AM - through Midnight
Significant Weather Outlook Noon - Midnight
Tornado Watch 5:00 - 10:00 PM
Short Term Forecast 603 - 700 PM
Severe Thunderstorm Warning 628 - 730 PM
Severe Weather Statement 650 - 730 PM
Severe Weather Statement 707 - 730 PM
Severe Thunderstorm Warning 723 - 900 PM
Tornado Warning 726 - 830 PM
Severe Thunderstorm Warning 849 - 1000 PM
7. Observations and Conclusions Power was lost in the Ellicott area between 6:00 and 7:00 p.m., and in many cases was not restored until the following day. Residents could have been warned of future weather warnings and statements via battery powered radios or TVs, or by NOAA Weather Radio. NOAA Weather Radio coverage is good in the Ellicott area from the transmitter on Cheyenne Mountain 35 miles west-southwest of Ellicott. Ellicott does NOT have tornado sirens and commercial power was unavailable anyway. If sirens would have been there, they would have needed to be hooked up to backup generator power. People may be surprised by the amount of damage to mobile homes done by straight-line winds. Straight-line winds flipped over and rolled the vast majority of the mobile homes in Ellicott. There had been torrential rains and large hail in the area an hour before the fierce winds hit. The ground was saturated, and the two foot long auger tie-downs seen at many sites were pulled out of the loose soil when the high winds hit. Augers that were left in the ground, along with the straps, were separated from the bottom frame of some mobile homes. Ellicott consists of numerous mobile homes, in both small parks and
on private land. During severe wind events, either tornadic or straight-line
winds, mobile homes are very vulnerable. It was remarkable that no
fatalities or serious injuries occurred during this event. If the
winds which struck the schools would have struck occupied mobile homes,
very serious injuries or fatalities would have been likely. The WCM
at WFO Pueblo, along with emergency management in El Paso county should
make a special effort to educate mobile home dwellers in that area, regarding
the NWS warning procedure and safety concerns.
8. Acknowledgments The survey team wishes to thank the many eyewitnesses who willingly offered valuable information regarding the event. We thank KRDO-TV for providing on-air information which prompted more eyewitness accounts. We thank KOAA-TV for providing aerial video of the Ellicott area. We thank the Colorado Springs Gazette for information regarding the storm event. We thank Matt Parker, graduate research assistant at Colorado State University, for a short and important video clip of the event. We thank the Warning Coordination Meteorologist at the National Weather Service Office in Omaha, Nebraska and the former Warning Coordination Meteorologist in Pleasant Hill, Missouri for their expertise regarding the damage survey. We thank El Paso county law enforcement and fire services, and emergency management for their help with information and access to the scenes. Finally, we thank the Salvation Army for providing refreshment.
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