NOAA's National Weather Service Weather Forecast Office

On Thursday May 22 2008 a wide and powerful tornado swept north northwestward for 34 miles from northeast of platteville in Weld County at 1126 AM MDT to 7 miles east northeast of Fort Collins in Larimer County at 1216pm MDT.   The National Weather Service tornado damage assessments conducted on Friday May 23rd and Saturday May 24th documented large areas of damage.  On the enhanced Fujita scale there were pockets of EF3 damage especially near the Missile Silo Park Campground west of Greeley and to homes and businesses in eastern Windsor.  Wind estimates in the heavily damaged areas were as high as 130 to 150 mph. 

The tornado was as wide as one mile at times along its path.  There was one fatality and 15 to 20 injuries.   Damage estimates are not finalized, but preliminary numbers from FEMA are 850 homes damage, with nearly 300 homes signficantly damged or destroyed.  Privately insured damages total 147 million dollars...and the Poudre Valley Rural Electric Association reported one million dollars of damage to electric transmission facilities.  

One question frequently asked is how unusual was this event.  Certainly it was not unusual in time of year (May and June are the peak tornado months in Colorado).  It was not unusual in location (more tornadoes are reported in Weld County than any other county).  It was slightly earlier in the day than normal, as we usually see tornadoes in the mid afternoon to early evening.  The track was longer than most, the tornado was moving fastern than most,  and a track moving north northwest is very unsusual.  Since 1950 there have been a total of 20 tornadoes of f3 and higher within Colorado.  This was the second f3 tornado reported in weld county since 1950.   On May 15, 1952 an F3 tornado injured 5 people within the county. 

For reference...the Enhanced Fujita Scale classifies tornadoes into the following categories:

EF0...wind speeds 65 to 85 MPH. 

EF1...wind speeds 86 to 110 mph.  

EF2...wind speeds 111 to 135 mph.

EF3...wind speeds 136 to 165 mph. 

EF4...wind speeds 166 to 200 mph.  

EF5...wind speeds greater than 200 mph.

Power line support sheared off at base.  Estimated winds 140 mph -155 mph.  Evaluated as EF3.   Location is near the Missile Silo Park Campground west of Greeley. 

Damaged home and tree.  Roof has been removed from house, with collapse of some exterior walls.   Tree debarked with only stubs of larger branches.   Estimated winds 130-140 mph. Evaluated as high EF2/low EF3  Location is west of Greeley near the Missile Silo Park Campground.

This appeared to be an automobile service facility and suffered a near total collapse.  Estimated winds 125-135 mph. Evaluated as EF2   Location is in estern Windsor.

This appeared to be a small professional building with extensive roof damage.   Estimated winds are 125 mph-135 mph.  Evaluated as EF2.    Location is in eastern Windsor.

Front and back of a two story small office building with garages on the back (downwind)
Side of the building.   Estimated winds are 130 -140 mph.    Evaluated High EF2/ low EF3)  Location is in eastern Windsor.

Doppler radar reflectivity image from 1144 AM MDT 5/22/08.

Doppler radar storm relative velocity image at 1144am MDT 5/22/08.