2:00pm Thursday change in forecast. *For Cottage Grove* Temperatures are struggling to get above freezing and latest data suggests we'll remain around 30-32° possibly through the evening or early night before warmer air arrives sometime between 9:00pm tonight and 3:00am Friday morning (we should be in the 40's by 6:00am). Therefore, freezing rain or possibly very light snow will be possible through 2:00am-ish, unless temperatures warm before then.
What is freezing rain? Warmer, above freezing air is currently above 3000-4000'' and this is acting like a lid to trap colder air below, preventing lower level temperatures from rising much and staying at 32° or below. Precipitation falls as rain above 3000' (where temps are above freezing) then as it passes below (where temperatures are 32 or under), it sticks like glue and freezes as ice. It can weigh down branches and power lines, causing some problems. It will take "mixing" of the atmosphere to mix out the "lid" of warm air above us and allow warmer air to move into the low levels. This was previously expected to happen by noon, but may be delayed until as late as sometime between 9:00pm tonight and 3:00am Friday morning. These times are not set in stone, as this is a very complex situation.
TRAVEL WEATHER: On Christmas Eve, rain will be the case with no snow at any of the regional passes, including I-5 at CA/OR border. Just some showers on Christmas Day, then rain again on Monday Dec 26 with snow levels well above the passes. Strong storm may then move in on Tuesday morning with 2" of rain, but we'll talk about this with a post on Christmas Eve.
When does the threat of snow/freezing rain end? By 3:00am Friday here. In Eugene, Thursday evening. North of Eugene, around noon or early afternoon on Friday. Portland may be Friday evening.
WINDS: Thursday around Portland can gust up to 50 mph and over 80 mph on I-84 along the Gorge. Winds Friday can gust to 30-45 mph. No wind concerns here, less than 10 mph.