Portland area sees final day of mild winter temps before arctic blast arrives

PORTLAND, Ore. (KOIN) -- Thursday will be the final day of average conditions as an arctic air mass dives south into Oregon and Washington on Friday.

Some of the coldest temperatures of the winter season are on the way for the Portland area. Thursday will bring the final day of near-average temperatures. Afternoon highs will warm into the mid-40s. That's still slightly cooler than the average Portland temperature of 47ºF.

A few scattered rain showers are likely across the Willamette Valley. Snow elevation levels will remain above about 2,000 ft. Mountain passes will remain snowy. Extreme caution should be used when traveling in or through the Cascades through the end of the week and weekend. Rain accumulation for lower elevations will be near a quarter of an inch to almost a half inch from the coast to the Willamette Valley on Thursday.

Buckle your seatbelt, because the roller coaster ride of temperatures gets underway Friday as an arctic air mass dives south throughout the day. Portland's high temperature on Friday will likely be felt during the early morning hours. Temperatures will continue to fall throughout the day. The timing of the transition from rain to snow is still unclear. Weather models are slowly starting to agree on the chance to see snowflakes in the city by the mid-morning hours on Friday.

Snow accumulation could be anywhere from an inch to six inches from Friday afternoon to Saturday afternoon. That's why the National Weather Service out of Portland has issued a Winter Storm Watch for the end of the week.

A KOIN 6 Weather Alert remains in place Friday and Saturday for Portland. That's where the chance of snow and dangerous cold is possible. Any form of winter precipitation that falls on Friday and Saturday will likely remain. Below-freezing temperatures will continue through the first half of next week.