While snow is not frequent in the Willamette Valley, it is certainly more common than the ice storm that hit Feb. 12-13

PMG PHOTO: PHIL HAWKINS - Flaggers control highway traffic as crews clear debris in the aftermath of a heavy ice storm that pelted much of the Willamette Valley Feb. 12-13.The February storms that pelted the mid- and upper Willamette Valley, rendering city streets into falling-tree disaster areas, fortunately, are a rare occurrence.

PGE officials described the icy aftermath as a "worst-in-decades storm" as hundreds of thousands of residences and businesses lost electricity.

Power companies deployed crews 24/7 throughout the area. Still many remained without electricity for days as the utilities kept fielding more and more reports of outages.COURTESY PHOTO: NATIONAL WEATHER SERVICE - Winter precipitation variances.

PGE dispatched roughly 700 contract and mutual-assistance line workers from as far away as Montana and Nevada to assess ongoing damages and restore power. The company also had more than 2,500 additional support and customer service personnel working to help with storm response and restoration.

Early in the week PGE issued a news release that noted: "Aggressive recruitment of mutual assistance from across the region has allowed us to double the number of crews working since Saturday to fix more than 200 miles of damaged transmission lines, extensive substation and feeder damage and more than 4,900 downed power lines as we reassemble the power distribution system."PMG PHOTO: PHIL HAWKINS - Second Street in Woodburn: fallen branches, trees and power lines due to ice and wind forced the closure of many streets and roads around the mid- and upper Willamette Valley this past week. The biggest part of the storm hit late Friday and early Saturday, Feb. 12-13.

Pacific Power sources said on Thursday, Feb. 18, that at times over the week upward of 80,000 customers in western Oregon experienced service disruption due to the destructive ice storms.

"Restoration in the mid-valley is going more slowly than we would like," said Allen Berreth, Pacific Power's vice president of operations. "The damage in the areas of Dallas, Stayton and Albany is devastating in places. Our crews and contractors have been working 24/7 with staggered rest and safety breaks all week, but we will continue at it until everyone is back in service."

A week after the biggest storm hit Feb. 12-13, almost all schools throughout the region remained closed due to power outages or loss of communication services, while most districts concentrated on keeping lunch services afloat.

Municipal and county public works crews also were spurred into overdrive as they worked to clear debris and reopen roads closed by downed trees and power lines.

Fortunately, uncommon

The ice storm made the valley's infrequent but more common snowstorms seem tame by comparison. Scott Weishaar, a meteorologist with the National Weather Service's Portland office said a storm of this magnitude occurs about every half-century.

"Ice and freezing rain in (the Willamette Valley) is not that uncommon; it happens on average every year or other year," Weishaar said. "To get an ice storm of this magnitude is pretty rare, probably a once in 50-year event."

Weishaar said the more common freezing rain storms drop one- or two-tenths of an inch of ice. This storm delivered an inch or more throughout most of the region.PMG PHOTO: PHIL HAWKINS - Ice and wind storms rendered heavy damage near the medical office buildings on the corner of Highway 211/214 and Fifth Street in Woodburn.

While it took a heavy toll on trees from Portland down to areas south of Albany, curiously the roads in more southern stretches were not affected other than those blocked by fallen trees or power lines.

"The reason the roads weren't impacted as much in some areas is that for the roads to be significantly impacted by ice you have to have temperatures in the mid to upper 20s," Weishaar said. "In areas where the temperatures remained near 30 or near freezing, the ice would not affect the roads. Basically in Salem and areas south to Harrisburg or so, air temps were right around or just under freezing. So roads weren't as primed to freeze as they were farther up north."

Why ice and not snow?

Weishaar said layers of warmer air from about 1,500 to 3,000 or 4,000 feet melted snowy precipitation as it fell. Once that precipitation hits the colder surface layer, it freezes.

"Snowflakes fall into that mild air and melt, and there is not much time to turn back into snow," Weishaar said. "So at about the final 1,000 feet or so it won't re-form into snowflakes, so they freeze when they hit the surfaces. If it's colder in the upper atmospheric layers, they stay as flakes when they come through that and come to the ground."COURTESY PHOTO: NATIONAL WEATHER SERVICE - NWS graphic depicts precipitation changes.

Had that been the case, the valley would have endured heavy snowfall over the weekend, and not the more catastrophic ice. Not all areas were affected the same.

"For reference sake, I live in Oregon City, and my temperatures at home were generally in the mid-20s," Weishaar said. "And there was still freezing rain; we had a little snow, but an inch and a half of ice on top of that.

"There was more snowfall from central Portland and north Portland than there was at points to the south and to the west."

Weather Resources

For information about winter weather, visit the National Oceanic and Atmospheric Administration webpage:

PGE storm information:

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