Amid the rain, hail and scattered snow that doused the North Coast on Friday, Santa Rosa was lashed with a fierce gust of wind that weather experts said may have been a small tornado.
It was all part of an extended storm front expected to linger through Saturday, then intensify, dumping an even larger amount of moisture on the region Sunday.
Strong winds of up to 50 mph accompanied Friday's system. And the gust that touched down in Santa Rosa, ripping off a large section of tin roof at a landscaping business and causing other damage, may have been a small tornado, a federal forecaster said.
The wind hit Sequoia Landscape Materials on Pacific Avenue and King Street and nearby houses just before 9:15 a.m. with what witnesses described as shaking and a roar.
"I saw the wind just pick up the roof and blow it up into the air," said Sue Minnigerode, owner of the landscape business.
The 150-foot section of corrugated tin roof was torn from the sturdy wooden posts supporting the outdoor shed and the entire structure then toppled over, coming to rest partly on Pacific Avenue.
Overhead power lines also were downed and debris was flung into nearby yards. A section of the tin roof came to rest high in a tree across the street.
Four workers were inside other buildings at the landscape business, but no one was injured.
Santa Rosa Fire Capt. Greg McCollum described the wind gust as "Kansas-type stuff." He stopped short of calling it a tornado, dubbing it a "funnel cloud."
But such formations don't touch ground or cause the type and extent of damage seen in the Santa Rosa neighborhood, said Steve Anderson, a meteorologist with the National Weather Service.
Instead, a small "rope tornado" may have caused the damage, Anderson said. The other possibility would be a "micro-burst," a strong downward draft typically caused by the unstable air associated with thunderstorms, he said.
Survey teams sent in after such events can usually tell which type of wind event it was based on the pattern of damage. Tornados produce a more isolated pattern — similar to that reported in Santa Rosa — while microbursts can have a more uniform path, Anderson said.
Although not rare, neither event is common in the area, he said.
"This is just a very intense front. Things have to come together just right on the West Coast for this to happen."
The stretch of Pacific Avenue between King and Wright streets was closed for several hours to allow for cleanup. Power was briefly knocked out to nearby houses, residents said.
Reported damage to other properties was limited to a split tree in one yard, a damaged fence and a roof on another home that was partially lifted by the wind.
Elsewhere, classes at Harmony Elementary School and Salmon Creek Charter School in Occidental were canceled Friday when the campuses lost power as rain and wind hit the area.
Harmony Elementary serves grades kindergarten through second, and Salmon Creek serves grades three through eight.
A morning power failure caused by wind affected nearly 700 customers in the busy commercial area of Santa Rosa Avenue at Yolanda and Kawana Springs avenues.
Rainfall in Santa Rosa topped about two-thirds of an inch between Thursday evening and Friday evening. About 1.5 inches fell in the coastal mountains west of Healdsburg, the National Weather Service reported.