CEDAR FALLS - Prioritizing cleanup was a necessity following a veritable avalanche of tree damage from Friday morning's storm.

The Cedar Falls Public Works Department used a familiar plan.

"It's kind of similar to how we do snow removal," said Public Works Director Bruce Sorensen. "Clear the arteries first and then get side streets done as they can."

The intense storm hit about 4 a.m. It toppled trees throughout the Cedar Valley, blocking streets, damaging power lines, crushing cars and damaging homes.

"We estimated 66 mph before the equipment went kaput," said Aubry Wilkins, a meteorologist with the National Weather Service in Des Moines, referring to wind speeds clocked at the Waterloo airport.

Though the NWS hasn't completed a survey of the damage in Cedar Falls, Wilkins said it is possible the storm produced a downburst over the city.

A downburst is described as a column of cold air descending very quickly during a thunderstorm. As the column reaches the ground, the rushing air produces strong winds.

A microburst would produce damaging winds extending less than 2.5 miles but with speeds in excess of 160 mph. A macroburst is larger but packs a slightly less powerful punch with winds in excess of 134 mph.

A macroburst could last up to 30 minutes, however, according to the National Weather Service.

About 8,000 Cedar Falls Utilities' customers had their power knocked out as utility poles and power lines were downed in the storms. While several hundred homes remained without power Saturday afternoon, nine electric crews - including crews from municipal utilities in other cities - will continue working until dark, said CFU spokesperson Betty Zeman.

Up to 500 customers could remain without power overnight, she said. CFU is advising customers to call 268-6999 this morning if their power has not been restored.

MidAmerican Energy reported that 81 customers in the Waterloo metro region were without power Saturday afternoon. Most of those were in the city of Waterloo, though a handful of customers were also in surrounding rural areas or neighboring cities.

No time line was given for when power to those customers would be restored.

Chad Turner took the day off from work at Principal Financial Group Friday. He didn't have much of a choice. A 3-foot diameter Linden tree from his boulevard fell across a car and blocked his driveway on Iowa Street. Up and down the street, the neighborhood worked to clear smaller trees and make the street passable. The big Linden was beyond their capabilities.

The scene in the back yard wasn't much better. Several trees were down, taking down electric service lines to several homes. One of the trees landed on his garage, damaging shingles, siding and a portion of the roof.

"You can see the outside from the inside, and that's not good," Turner said.

After a full day of clean-up efforts, Cedar Falls Fire Rescue Battalion Chief Larry Burman said the department hasn't been called for emergency medical or rescue help. The storm turned thousands of people usually not accustomed to running chain saws and other equipment into lumberjacks, he said. And that can lead to trouble.

"Nobody has fell off a roof or ladder, that's most amazing thing to me. Some of the more dangerous times is days after the storm," Burman said.

The city of Cedar Falls opened the compost site in the 300 block of North Main Street to take tree debris until it is no longer needed. That facility will be open from 7 a.m. to 8 p.m. until further notice. The city also will waive fees for yard waste collection pickup Monday.

Street crews were assisted by parks workers as the city worked to make streets passable as soon as possible.

Residents in many neighborhoods kept working on clearing storm damage as additional thunderstorms rolled through Friday morning.

Clark Vanhauen donned a poncho to shed rain as he helped clear debris from his neighbor's home. Vanhauen had a pine tree crash into his house. It damaged an awning, siding and knocked out his electric service connection.

"It's nothing that can't be fixed," Vanhauen said.

Mike Dowd, the next door neighbor, was working with Vanhauen and a friend to load up a trailer to take brush away. He had a tree down in the front yard and two in the back, one which struck his garage. He pointed to the pine tree that struck a glancing blow to Vanhauen's house and noted how it could easily have caused major problems. In the process, he noted a larger tree above his home had a large split. Dowd paid $2,000 to have some trees and brush cleared last year. It appeared another bill may be forthcoming.

Large trees down across the road blocked access up and down Madison Street in the Cedar Heights area. Many of the trees sheared off right at the base. Other trees were uprooted, and some lost major branches that were large enough to appear to be trees unto themselves at first glance.

Dave Mitchell and Jamie Brandt didn't bother with rain gear as they worked at sawing up trees at the home of Mitchell's mother on Sunnyside Circle. In the backyard, about 10 neighbors worked up and down the block helping each other.

"It's quite a group effort," Mitchell said.

More than 15 residents from the Windsor Nursing and Rehab Center had to be moved to the Parkview Nursing and Rehab Center Friday because of roof damage and a power outage at the Cedar Falls facility. Nicole Bateman, a nurse at Windsor, was uncertain when the residents would be able to return. None of the residents were injured.

At the Waterloo Regional Airport, a 4 ton helicopter broke loose from its moorings and crashed into a fence during the storm.

Chris Preston of Livingston Aviation said a couple of the rotor blades snapped. Despite a couple of near misses from tornadoes, the airport hadn't had aircraft damaged for nearly three decades. The last time was July 9, 1980, 29 years and three hours from Friday's storm.

The city of Waterloo suspended normal size restrictions at its yard waste drop-off site and has marshalled all available resources to help clear downed trees and limbs from streets, parks and golf courses.

Leisure Services Director Paul Huting said the effort could take weeks.

"We took a big hit, it's a mess," Huting said. "Our number one priority is getting the trees cleared off the streets, but we've got a lot off damage at the golf courses and the parks too."

The Irv Warren golf course, which is expected to host professionals for the Greater Waterloo Open later this week, was of particular concern.

"The course is totally saturated, and there's a lot of limbs down," Huting said. "With the Waterloo Open coming up, that's not a good thing."

Golf crews are working to clear the course, which was closed Friday, but most city park and forestry crews were clearing streets, which was a public safety concern.

Mayor Tim Hurley said he's directed staff to share resources and manpower to clean up the storm.

"Our mowing crew, for example, isn't mowing," he said. "They're helping with debris."

The city also is checking to see if workers hired through a federal employment program to help clean up flood debris from June 2008 can be shifted over to assist in storm debris cleanup.

The yard waste dump site on Easton Avenue will accept all storm-related branches, logs and brush. The usual size restriction is waived until further notice, but citizens are asked to cut the debris up into the smallest size practical. The site is open seven days a week from 7 a.m. to 7 p.m.

Hurley said the city is not contemplating a special, and costly, curb-side collection of storm debris at this point.

Crews at the University of Northern Iowa said it will be several days, possibly even weeks, before the extent of damage on campus can be assessed completely.

Winds damaged at least 350 trees on the campus, and of those at least 100 will have to be completely removed, said Paul Meyerman, assistant director of operations planning.

"You go out to one area and say 'Oh crud.' Then you turn a corner, and it just never ends," he said.

The storm also damaged both Latham Hall - windows were broken and a tree punctured the roof - and Price Laboratory School, where windows also were broken. Meyerman said the roof has been patched and crews are working to cover the windows to keep from incurring any further damage.

Dean Shoars, director of the physical plant, is hopeful the area near 23rd and College streets can be cleared in time for the College Hill Arts Festival, scheduled for July 17-18.

Insurance adjusters scrambled to get out to help homeowners file claims. Kendall Kramer, a manager with State Farm Insurance, said his company was bringing in help from outside the area to set up a catastrophe center.

Courier Staff Writers Emily Christensen, Tim Jamison and Matthew Wilde contributed to this report.