SEATTLE -- The snow may be on its way out in the Western Washington lowlands, but it's still going strong up in the mountains. Heavy snow and poor visibility has forced the DOT to close a portion of Snoqualmie Pass once again.

Late Monday night, just hours after WSDOT reopend the westbound lanes of I-90 across the pass at 8:15 p.m. Monday, officials announced the scheduled closure of the eastbound lanes at midnight Tuesday for avalanche work at milepost 47 near Denny Creek, five miles west of the summit.

Due to the nature of the work, DOT officials could not estimate the reopening time.

As much as 12-18 inches had fallen by early Monday, while another 12 inches were expected in the higher passes during the day, although the snow level might rise just far enough above Snoqualmie Pass to change it to rain there. A Winter Storm Warning remained in effect in the Cascades until 6 a.m. Tuesday.

Down in the lower elevations, snow fell for several hours Sunday evening, blanketing much of the region. Many areas had as much as 2-4 inches, with the a few spots over on the Kitsap Peninsula reaching 6 inches. It caused several spinouts and collisions across the area.

The Seattle Department of Transportation had 20 plows out overnight, and spokesman Rick Sheridan said crews were using salt on the roads, after snowfall totals reached four inches in some neighborhoods. Spokeswoman Marybeth Turner says trucks spread salt on arterial, hills, bus routes and around hospitals from 8:30 p.m. Sunday to midnight.

"The director of the Department of Transportation authorized the use of salt and it's had a very positive effect on our roadway conditions this morning," Sheridan said.

Last week, Mayor Greg Nickels, facing criticism from frustrated residents over the lack of snow removal from the December storms, ordered the Department of Transportation to begin using salt as a tool to clear major arterials during future snowstorms.

But promised warm air arrived just before midnight, turning the snow to rain and starting the melting process. Most main roads and highways in the greater Seattle area were bare and wet Monday morning, but slush and snow still on the side streets made for a tough commute in some areas.

Several area school districts delayed the start of classes (see complete list), and some Metro bus routes were block due to impassable roads (check route alerts).

Scattered power outages caused by snow had utility crews busy early Monday morning, and Seattle City Light reported that about 1,000 customers were still without power at about 8 a.m., down from a peak of 20,000 overnight. Puget Sound Energy reported about 6,600 customers without power on Vashon Island.

The snow in the lowlands is gone for the foreseeable future, as temperatures throughout the Puget Sound area should remain warmer throughout the week than what we've seen for the last three weeks, as an incoming storm brings in much warmer air and rain.

Rain showers are expected to taper off Monday afternoon, but Tuesday will bring more rain lasting through Thursday morning, with snow levels over 5,000 feet and lowland temperatures approaching 50.