That accelerated quickly! Moderate to heavy rain suddenly arrived in the metro area in the past hour and now ice is accumulating (technically accreting) where temps are below freezing. I-84 immediately closed in the Gorge. 1/2 hour before that time I drove it westbound just as rain beginning and there were a LOT of semi-trucks flying through at 50-60 mph. I’m guessing that didn’t go well once the heavy rain started at 25 degrees. Where will the ice storm continue? Take a look at the map:
Yep, in the areas exposed to the cold east wind coming out of the Gorge. The cold air is only 1,000′ over Troutdale.
Within the blue area above an ice storm has begun and will continue tonight. Remember that temperatures have to be below 31 degrees for roads to turn icy, so in much of east Portland this will be a damaging event for trees/powerlines but not terrible on the roads.
ALL OTHER AREAS west of the Cascades are IN THE CLEAR for additional icing on roads. This includes all of north/west/south metro areas. Once you go south of the Multnomah County line in the east metro area you are mainly out of the freezing air. You can resume your normal activities in those areas
Chief Meteorologist Mark Nelsen