Who would have thought these 12 days of Christmas would be so challenging for forecasters? Actually I suppose this is the busiest time of the year for meteorologists in the Pacific Northwest. So lets just jump right into it.
The forecast for the metro area worked out just fine today, but the snow was heavier than expected up in Columbia County where several inches fell quite close to sea level. Also we had a band of showers drop some heavy snow right over Clackamas and northern Marion counties this evening. The official snow total in Portland? Yes, once again it wasn’t measurable…just a trace at the NWS office.
But check out those totals in the hills around the metro area!
If you live up around 1,500′ you really scored…after two winters of very little foothill snow it’s nice to see it back.
Showers will continue off/on tonight, although in general the airmass is drying out as modified arctic air filters down into the Pacific Northwest. That dry/colder air has made it through the Gorge and the east wind has started blowing in the usual spots. Already gusting over 30 mph at Vista House. The wind will blow until further notice…sorry! Tonight’s low temps won’t be too cold assuming we don’t get much clearing. Probably just below 30 here in Portland. I raised the forecast highs and lows the next few days since it’s obvious models have overdone the amount of cold air to our north, plus too much wind at night will likely keep PDX from dropping much below 22 the next few nights. Still, high temps will likely just creep a bit above freezing tomorrow (32-34 metro area) even with mostly sunny skies. Colder air will continue moving south through the region and then through the Gorge the rest of the week, but it definitely won’t be any sort of mega arctic-blast. Just 2-3 days ago the northern stream of the jet was expected to dominate until further notice. Instead we’ve seen models gradually allow more and more energy from the southern stream of the jet (milder and moist Pacific air) to move north over us the rest of this week.
My 7 Day Forecast this evening is mainly based on the ECMWF and its ensembles keeping the California system Wednesday to our south; thus the dry forecast.
Wednesday is a real challenge. Most models other than the ECMWF are pushing some sort of moisture up north over Western Oregon Wednesday. That’s right over the top of the cold air. If they are correct, snow is likely coming for at least parts of the Willamette Valley Wednesday. Here’s the WRF-GFS precipitation forecast ending Thursday AM, classy…nice dry hole over PDX:
Beyond Wednesday, all models agree on a “transition event” this coming weekend as we get rid of the lingering cold airmass. Most likely a snow to freezing rain to rain event. The ECMWF earlier today looked very similar to January 2004 with a low pressure system brushing up against the coastline but never really moving north of our latitude. That’s a sort of “meteorological drive-by”. It doesn’t dislodge the cold air, cold east wind continues, but a bunch of moisture arrives over the cold air. What the ECMWF shows is a typical metro snow/ice storm Saturday & Sunday. The GFS gradually warms us up Thursday-Saturday and we’d probably see little/no snow next weekend. The evening GEM is more like the ECMWF showing a snow or ice event next weekend.
Chief Meteorologist Mark Nelsen