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Portland Bureau of Transportation

Phone: 503-823-5185

Fax: 503-823-7576

1120 SW Fifth Ave, Suite 800, Portland, OR 97204

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ALERT: Frost and black ice alert for holiday weekend travelers

December 30, 2011




Cheryl Kuck

Portland Bureau of Transportation



(Portland, Ore.) — A hazardous weather outlook issued by the National Weather Service indicates a storm moving in this afternoon or evening with more rain, fog and frost in the valley and snow in the mountains, including a chance of snow in Portland’s highest elevations on Council Crest and Mount Scott. With temperatures forecasted to drop to freezing tonight and Saturday night, the traveling public is advised to be alert for frost and black ice citywide tonight, Saturday night and Sunday morning.

Landmark elevations at or above 1,000 feet in Portland include Council Crest at 1,073 feet, Mount Scott at 1,050 feet and the top of West Burnside at 950 feet. For more elevation information, view the Portland Plow Map

Black ice is treacherous because it is hard to see. It forms when roads are wet and temperatures drop to freezing. Even though the roads look like they are just wet, they can be very slick. The traveling public is advised to be especially careful on bridges, overpasses, tunnels, roads that wind around rivers, and in shady spots. These areas freeze first and thaw last.

When traveling in conditions with fog and frost, the public is advised to exercise caution, slow down, allow extra stopping distance, use headlights and share the road responsibly. For tips on how to bike on black ice, see  

Transportation crews are monitoring conditions and continuing routine operations today to keep streets safe and clean. As long as rain continues to fall and remains in the forecast, crews do not apply anti-icing chemical because the rain will just wash it away. When the rain stops and conditions are dry enough, crews may apply calcium magnesium acetate, a liquid derivative of salt, on major arterials to help prevent ice from forming.

Residents are advised to familiarize themselves with for current weather, street closures, and highway road conditions. The public can report road hazards to 503-823-1700.