Chance of Freezing Rain Tonight

From the Portland National Weather Service:

Freezing rain is possible Tuesday night and Wednesday for much of the interior lowlands. The stagnant weather pattern is expected to end as a cold front moves through the area Tuesday night into Wednesday. Currently much of the interior lowlands are under a strong temperature inversion with freezing temperatures at the surface and above freezing temperatures above ~1000 to ~1500 feet. As the front moves through, precipitation could fall as freezing rain for the interior lowlands. The main forecast challenge is when the surface temperatures go above freezing to end the freezing rain potential. A secondary challenge is the amount of freezing rain accumulation.

PRIMARY AREAS IMPACTED:

• Willamette Valley

• Southwest Washington interior

• Columbia River Gorge

• Upper Hood River Valley

• The lower valleys in the Coast Range and Cascade Foothills may also be affected.

IMPACTS:
Light freezing rain is possible with accumulations generally a tenth of an inch or less. Main impact is slippery roads and walkways.

If the current forecast timing of the event plays out, the greatest impact will be during the morning commute Wednesday morning and extended through Wednesday afternoon for the Columbia River Gorge.

TIMING: Tuesday night (after midnight) and Wednesday.

Willamette Valley and Southwest Washington interior – Late Tuesday night into Wednesday morning. Columbia River Gorge – The west end will likely have similar conditions as the Willamette Valley with perhaps a longer duration.

The east end will likely start as light snow then transition to period of freezing rain Wednesday, and finally to rain Wednesday evening.