It’s pouring outside and for much of the metro area temperatures are below freezing. Over the next few hours the areas that get heaviest ice accumulations will be where temps remain well below freezing (instead of 32-33) and exposed to the cold east wind blowing out of the Gorge. That means lots of ice buildup in the West Hills, East Portland, and areas around the Gorge; not too much elsewhere. Expect IMPROVING conditions in Clark county, south metro & west metro. This is perfectly normal for an ice storm. Biggest impacts are always in the city and closer to the gorge.
- Freezing rain continues through mid-afternoon, then turns to lighter showers for MOST of the metro area
- A few spots that have gone above freezing (mainly IN Portland and eastside) will go back below freezing for a few hours
- Areas ABOVE freezing (westside and south metro) will likely stay above freezing through the rest of this event.
- 1/4 to 1/2″ is likely by sunset in the areas mentioned above
- Roads west & south metro and up in Clark county should improve from this point forward.
- Roads central/east metro turn a bit icier, but even they improve once the east wind stops
- Temps in all areas, except east of Bridal Veil in the Gorge, warm above freezing this evening and ice slowly melts.
Our ice storm is transitioning into one in which the usual areas get hammered. That includes the hills and all areas exposed to the sub-freezing air pouring out of the Gorge. Away from those areas temperatures are gradually creeping above freezing.
A couple big meteorological notes this morning:
- The easterly strongest gradient I’ve ever seen in the Gorge (pressure difference from DLS to PDX) is occurring right now. 15.6 millibars! The peak gust at the Corbett sensor hit 85 mph this morning before the freezing rain hit. Of course now it’s slowing to a stop. That’s the highest gust at that location since at least the January 2009 damaging wind event.
- Even more interesting is a mixing of some “warmer” downslope type wind with the colder Gorge wind the past few hours. Wanderer’s Peak at 4,000′ SE of Estacada had warmed to 35 with southerly wind at midnight, but has dropped back to 21 with cold air coming right over the top of the Cascades again. That would also explain why we’ve seen a few spots go back to snow near the Cascades. PDX warmed up to 34 with a straight east wind gust over 40 mph. The usual wind direction for the gorge outflow is ESE. It’s some geekery, but the point is that downslope wind warmed some areas up a couple degrees and now it should be back below freezing the next few hours east of I-5 in the city.
The east wind and sub-freezing temps should suddenly disappear right around sunset as the cold front passes overhead. Then we all thaw in the metro area.
Chief Meteorologist Mark Nelsen