Ice Storm likely to hit Thursday afternoon
By Rod Hill on 2022-12-20
A significant accumulation of freezing rain and sleet is set to move into the I-5 corridor during the day Thursday. After a dry start to the day, light icy precipitation will slowly develop Thursday afternoon. Due to cold temps in the low to mid 20s and gusty east winds, the initial wave of moisture may evaporate. Keep in mind, it does not take much ice to make travel difficult. Right now, getting home by Thursday noon in Portland and Salem is the best advice.
Futurecast shows (salmon color) steady, widespread freezing rain and or sleet falling Thursday evening at 9:00 pm. Ice is expected in the west gorge and snow takes hold around Hood River. Notice rainy pockets (green color) along the immediate coast but also icy locations. Precipitation may break up from time to time, but enough total ice is expected through the day Friday for much of the I-5 corridor to see 1/4" icing or possibly heavier. Snow in the central and east gorge could stack up to 6" of fresh snow Thursday night through Friday.
A dry Wednesday with Arctic air arriving during the day will set the stage for 2-3 days of icy precipitation. Valley temperatures Thursday will hold in the low to mid 20s with rain falling from a warmer air mass aloft and freezing into sleet on the way down or freezing rain upon surface contact. One will have to get to 4,000' over the Cascades to find a snow transition, meaning all precip below 4,000 will be rain freezing into ice, including over the Coast Range. Heaviest precipitation in terms of ice accumulation will fall Thursday night through Friday night.
While parts of the Willamette Valley may see warming on Friday with ice changing to rain, areas impacted by gusty east winds will see sleet and freezing rain through Saturday morning, followed by warming during the afternoon as a weather front arrives and scours out the coldest air as winds veer to the west. I should mention east winds will pick up during our dry Wednesday and blow 15-30 mph at times Thursday through Saturday morning, keeping cold air in place.
The source of the cold air is a large Arctic air mass (seen in purple) Thursday at 1:00 pm that will brush through eastern Washington and Oregon has it shifts southward across the midwest. The air mass will produce widespread cold of 30 degrees below normal are temperatures across the country. East winds will pick up Wednesday, advecting cold air into the day Saturday.
Widspread warming will take hold Saturday night behind a Pacific weather front. Christmas Day may warm to 50 degrees with rain showers.
(Graphics for this story are compliments of KGW TV)
Rod Hill
Tracking possible Friday sleet and freezing rain