A potent rainstorm that launched a predicted five-day run of wet weather on the North Coast dropped more than 2 inches of rain Wednesday on some areas of Sonoma County and beyond.

The deluge flooded several roadways during its peak, cut power to thousands of people, toppled trees and sent motorists skidding during the morning commute.

But emergency officials said the worst likely still lies ahead as successive storms saturate soils, weaken hillsides, loosen trees and generate runoff the ground can't absorb.

"It's not quite enough rain yet to really be problematic, so we're keeping our fingers crossed," said Tom Kelly, senior administrative assistant for the Santa Rosa Department of Public Works. "But it's bound to be a big week for us."

As much as 6 inches of rain could fall on the Santa Rosa Plain by Sunday, National Weather Service meteorologist Diana Henderson said.

In the coastal hills, total rainfall could reach a foot or more, she said.

"It's going to come in spurts, but there is a lot of moisture out there, so it's just the beginning stages," Henderson said Wednesday.

"Give it time," said Rob Houweling, Sonoma County transportation operations coordinator. "If the storm rolls out like they say it's going to, we'll probably have flooding, slides, trees, those issues."

After several hours of hard rain around the county before noon Wednesday, Henderson said the next torrent will probably come later today, with rain becoming even heavier overnight.

But Wednesday's numbers were impressive. Totals recorded by the AccuWeather forecasting service for the 24-hour period that ended at 4 p.m. included Cazadero, 2.50 inches; Guerneville, 1.85 inches; Healdsburg, 1.75 inches; Sebastopol, 1.70 inches; Calistoga, 1.69 inches; Cloverdale, 1.66 inches; and Middletown, 1.64 inches. The Mendocino County town of Boonville received a whopping 2.75 inches.

Santa Rosa's total was 1.14 inches.

The rain came so fast that a homeless couple who had built a platform to use as a bed inside a 36-inch culvert along Santa Rosa Creek were violently flushed out of the pipeline and into the creek while they slept, Santa Rosa Fire Battalion Chief Mark Basque said.

The platform, built in a lateral culvert north of the Maribelle Apartments near Dutton Avenue and West Third Street, was high enough that any storm water usually flowed underneath, Basque said. But heavy rainfall in the neighborhood around 9:30 a.m. Wednesday flushed them and their dog, Scrappy, into the frigid creek water. They were able to climb out before firefighters and paramedics arrived.

The man and woman were taken to Kaiser Medical Center for treatment of exposure and lacerations, and their dog to county animal control until they are able to retrieve it, Basque said.

The rainfall also made for a messy morning commute, with a dozen or more mostly non-injury crashes reported on local highways, the CHP said.

The Highway 121 corridor near Sonoma was hit hard, with five crashes in a two-hour period between Highway 37, near Sonoma Raceway, to South Central Avenue in the Carneros region. In one case, a motorist struck a Schell-Vista Fire Department engine near Meadowlark Lane, causing minor damage, Chief Ray Mulas said.

Elsewhere, a car spun off Highway 101 on the Cotati grade, and a four-car collision in Windsor left wreckage strewn across the same highway, the CHP said.

"You have to really adjust yourself for what's going on," CHP Officer Steve Fricke said in the aftermath. "I mean, the roadways are wet, and the faster you go, the easier it's going to be for you to spin out. So we really have to reduce our speeds and watch that following distance."

The rain and heavy winds along the coast, gusting upward of 45 mph, brought down a few trees. One that fell across Highway 116 west of Duncans Mills was quickly removed, Monte Rio Fire Chief Steve Baxman said.

A eucalyptus tree toppled on Lakeville Highway, about halfway between Petaluma and Highway 37, though luckily it fell away from the road, Houweling said.

Road crews spent the morning attending to numerous problems around the county, largely involving clogged storm drains that caused heavy rainfall to pool on local streets.

"It's widespread," Kelly said. "It's not just one spot."

So, too, were power blackouts that at one point early Wednesday affected 700 customers in Sebastopol, and more in Petaluma, Penngrove, Sonoma, Valley Ford and elsewhere.

Another blackout of about 270 customers hit downtown Santa Rosa at noontime, and later PG&E reported 2,400 customers without power in or near Healdsburg.

Ed Buonaccorsi, emergency preparedness coordinator for Santa Rosa, said the storm arriving today is expected to move through the area far more slowly than did Wednesday's, meaning it should bring more rainfall to the larger area.

But what appeared to be a pause in the rain on Wednesday afternoon and evening was a welcome break, allowing early rainfall to dissipate, he said.

City officials were still warning residents to be alert for problems in low-lying or trouble-prone areas, while the city of Petaluma was offering sandbagging materials at the north end of Hopper Street, near Lakeville Street, on the east side of town.

"Everybody's going to get their fair share of rain," Henderson said, "especially by the end of the weekend."

You can reach Staff Writer Mary Callahan at 521-5249 or mary.callahan@pressdemocrat.com.