I came into work today pretty relaxed, thinking for now we were pretty much past all this winter stuff for most of us.
The evening models have come in and now it’s pretty clear we’re going to have some sort of snow/ice event in the Columbia River Gorge once again. Now tomorrow there is a low pressure area that tracks through southern Oregon, that will pull very cold Canadian air back down into Eastern Washington once again. Then a 2nd low approaches the coastline Wednesday with a tremendous feed of moisture showing up by evening. That pulls the cold air in tight against the Cascades…into the central/eastern Gorge. You can see it clearly in blue on the 1pm surface pressure map off the UW WRF-GFS model:
This is a classic setup for ice/snow in the Gorge. Note there isn’t much making it west of the Cascades, so typically we don’t get freezing rain/snow in this pattern westside.
The easterly flow doesn’t disappear until late Wednesday night or early Thursday. At that time the warming southerly wind takes over. But there will be a LOT of precipitation until that time. Check out the forecast precipitation:
It won’t be all snow in the eastern Gorge because the cold air will be thinning quite a bit by Wednesday evening and the airmass overhead is warming rapidly. But maybe enough for 8-12″ snow before a changeover. Note the snow forecast:
This could be a big ice storm again in the western Gorge where the cold air will be too thin to support snow west of Bonneville Dam…sorry folks! If this happens, it will be the 5th ice storm with at least 1/2″ ice this winter…I haven’t seen that in my 26 years forecasting in Portland!
At this point it’s unlikely, but still possible freezing rain creeps into the eastern parts of the Portland metro area near the Gorge…we’ll be keeping a close eye on that.
Chief Meteorologist Mark Nelsen