Carl Cerniglia with the National Weather Service says the damage has the tell-tale circular pattern of a tornado and the storm has a rating of EF1 on the Enhanced Fujita tornado rating scale, but he still has more damage to survey.
EF1 is the second-weakest rung on the scale which goes as high as 5. By surveying the damage, meteorologists estimated the top wind speed inside the core of the tornado was 110 mph -- just below EF2 criteria. The width was estimated at 150 yards and it touched down intermittently over a 9.6 mile long path.
Meanwhile, residents in the Enumclaw and Buckley areas were still cleaning up after the tornado touched down Sunday afternoon, knocking over trees and damaging a few structures.
At the Kaelins' home in Buckley, huge trees were toppled and a fifth-wheeler was on its side after being carried a good 70 feet by the wind. A two-and-a-half-story hay barn was reduced to rubble.
"Unbelievable... un...unbelievable," said Shirley Kaelin.
The Kaelins were out to dinner when the funnel cloud emerged from the sky.
Grainy cell phone video from a viewer shows what appears to be a tornado touching down in the distance.
Shirley Kaelin says she was glad they weren't around to experience it.
"It must have been God's will," she said. "We could have been home...right in the middle of the mess."
The National Weather Service makes the official call whether the storm is a tornado. Sometimes strong downdrafts from passing thunderstorms can also bring damaging winds.
But one witness says he didn't need to wait until Monday's confirmation to know it was a tornado.
"I looked up in the sky and noticed these dark clouds swirling," said dairy farmer Byron Anderson.
Anderson was out in the pasture where his cows graze, when he saw the wind lift water out of Lake Tapps.
This photograph taken by Ian Bond shows the barn that was destroyed in Sundays' tornado from a photograph taken Dec. 5, 2008 when spectacular Lenticular Clouds formed over Mt. Rainier
"And it hit the tree line and started snapping limbs and leaves and they disappeared up into the clouds," Anderson said.
Amid his damage, a 70-foot concrete silo that is now gone.
The storm moved out of the northwestern Buckley area and toward the northeast through the Green River Gorge into Enumclaw, putting the GE&B Nursery right in its path.
Owner Gary Horton said there was an eerie calm, and then in an instant, a huge downpour. Moments later, trees began bending and limbs were snapping off. Several plastic tiles blew off the nursery greenhouses, and the main office suffered roof damage.
Horton said he ran for cover inside.
When the storm passed, he found a large tree had toppled in the front yard of the nursery. He said he was thankful the storm waited until after he had closed for the day because that tree fell right across the front entry way.
The storm continued its northeasterly track, passing by the home of John Vick about a mile away from the nursery. Tree limbs were scattered about his horse range and his rocking chair that's normally perched on his front porch was nowhere to be found.
For Vick, it's not the first time he's had to deal with strong winds. During the windstorm of Dec. 4, 2003, Vick had just left his car to pick up the mail when a tree came crashing down, destroying his car.
Overall, officials do not yet have an estimate of damage across the region. No one was injured.
Seattle Sets Daily Rain Record
The apparent tornado was just part of a stormy day across Western Washington, fueled by an intense area of low pressure moving through. Heavy showers and thunderstorms dotted the scene through the day.
Some 1,300 Puget Sound Energy customers lost power in the storm, and strong gusts over in Bremerton also caused a homemade plane to flip as it taxied at the Bremerton airport. Police said the pilot was not injured.
Seattle received 0.93" of rain, almost tripling the previous record for wettest Sept. 6 on record, which was 0.38" set in 1980. Olympia also set a daily record for heavy rain.
Tornadoes Rare In Washington
Washington averages about two tornadoes a year somewhere in state, most are the weakest EF-0 or EF-1 on the Enhanced Fujita Scale.
Strong tornadoes need severe thunderstorms fed by large changes in temperature in the upper atmosphere. Severe thunderstorms typically need much colder air moving in aloft to make the air very unstable.
The so-called "Tornado Alley" in the Midwest is ripe for severe weather due to frequent battles between cold, arctic air marching south of out Canada colliding with very warm, moist air moving north from the Gulf of Mexico.
But in the Pacific Northwest, the cool waters of the Pacific Ocean are a great moderating force that keeps temperature changes from being too drastic, and thus tornadoes are quite rare. However, in today's case, we did have a very cold pool of air from the Gulf of Alaska move in with the low, helping to make our atmosphere very unstable and trigger heavy rain and thunderstorms.
There has only been one deadly tornado in recorded history in Washington -- an F3 tornado that touched down in Vancouver on April 5, 1972. Six people were killed and 300 were injured in that tornado.