North Cascade Foothills, North Cascades
*NOAA Issue Date: 1/16/2017 05:04:00 AM Major ice storm appearing likely Tuesday and Wednesday for the Hood River and Wind River valleys ... The Columbia river gorge ... As well as many valleys within the gifford pinchot national forest ... ... Significant icing also possible Tuesday for the greater Portland and Vancouver metro area ... Nearby valleys in the coast range and Cascades ... And the central Willamette Valley ... . Yet another ice storm is appearing more likely for the inland valleys of southwest Washington and extreme northwest Oregon Tuesday ... Likely lasting into Wednesday in and near the Columbia river gorge. Temperatures will be slow to recover from several days of subfreezing weather ... Especially where there is snow left on the ground from last weeks Portland area snowstorm. Temperatures are expected to remain near or below freezing under Valley inversions today ... Then remain steady near or below freezing tonight and Tuesday morning. Meanwhile ... A very moist Pacific frontal system will spread rain across the region Tuesday morning ... Increasing Tuesday afternoon and evening. There will likely be several hours of rain before warm air aloft can work its way down to the Valley floors ... Leading to the potential of several hours of freezing rain. Areas in and near the Columbia gorge will be hardest hit ... As they will be the last to climb above freezing. It is very possible that locally over an inch of ice will accumulate in the Columbia gorge ... Hood River ... And Wind River valleys by the time temperatures crawl above freezing Wednesday. ... Winter Storm Watch in effect from Tuesday morning through Tuesday afternoon for the valleys below 2000 feet in the north Oregon Cascades and foothills ... The National Weather Service in Portland has issued a Winter Storm Watch for significant icing in the valleys below 2000 feet ... Which is in effect from Tuesday morning through Tuesday afternoon. * Timing Rain is expected to develop Tuesday morning ... Increasing throughout the day. Subfreezing air trapped in the Cascade valleys will likely cause freezing rain and significant ice accumulation Tuesday morning. Valley temperatures are expected to slowly climb above freezing Tuesday afternoon ... Ending the freezing rain threat Tuesday evening. * Ice accumulation Valley ice accumulation of up to one third of an inch. Ridgetop temperatures will be significantly warmer ... So no significant icing is expected in the higher terrain. * Impacts Several days of very cold temperatures will make ground surfaces like roads and sidewalks very receptive to ice accumulation. It may take a couple hours of temperatures above freezing to completely end the freezing rain threat at any given location. Ice accumulation on trees and Power lines may result in downed branches and lines ... Which would bring the threat of Power outages Tuesday. Precautionary/preparedness actions... There is a potential for significant ice accumulations. Future driving ... Bicycling ... And walking conditions may become hazardous ... So it is important to Monitor the latest forecasts. Also ... Be prepared for potential Power outages as ice may bring branches and Power lines down Tuesday.