Arlington, Snohomish could see serious flooding this weekend

Officials are urging Snohomish County residents to plan ahead — and not to drive on flooded roads.

ARLINGTON — Prepare for major flooding and possible landslides throughout the county this weekend, as heavy rain was forecast to swell three major rivers in Snohomish County.

As soon as Friday night, the main stem of the Stillaguamish River could rise to flood stage, according to the National Weather Service.

Already, Stanwood city officials have announced the closure of a flood-prone stretch of Marine Drive starting at 9 a.m. Friday.

The weather service issued a flood watch through the weekend, although a volatile forecast means the severity of flooding remains uncertain.

“We are expecting flooding,” said Justin Pullin, lead forecaster at the NWS in Seattle. “Both river flooding and potentially some urban flooding as well.”

The Stillaguamish is predicted to rise first, causing minor flooding Friday in the Arlington area. The current forecast calls for the river to come within inches of major flooding by Saturday afternoon. But meteorologists said it could be more or less extreme.

Exactly where the heaviest rain will fall is still unclear, and that will directly influence the magnitude and whereabouts of flooding.

The Snohomish River is expected to overflow later, with minor flooding by Saturday night and moderate levels by early Sunday morning. Residents of the Skykomish River Valley may see minor flooding starting Saturday.

The county Department of Emergency Management is encouraging residents to prepare.

Plan your driving routes ahead of time and avoid roads that may be covered in water, department spokesperson Scott North said.

If you see water over the road, don’t drive through it.

As little as 1 foot of water will make most vehicles float.

“And most people who drown in flooding, drown in vehicles,” North said.

A heightened risk for landslides lasts into Saturday, Pullin said.

Snoqualmie Pass and other areas had warnings of moderate avalanche risk.

There’s also the potential for high winds. They were predicted to pick up late Thursday and last through Saturday.

By Saturday night, cooler air may bring mixed snow and rain in the lowlands, or even some snow accumulation.

Stanwood was planning to once again construct “Fort Freeburg,” a temporary sandbag berm to protect the town from the Stilly’s rising waters.

While it’s up, some roads will be blocked and school buses will take alternate routes.

Marine Drive under the Highway 532 bridge will be closed until the threat of flooding subsides.

“It’s something we have to build when we have these kinds of severe weather situations,” city administrator Jennifer Ferguson said. “We are preparing.”

Check river predictions at water.weather.gov and real-time flood information at snohomish.onerain.com.

Julia-Grace Sanders: 425-339-3439; jgsanders@heraldnet.com.