Exciting End to Winter Ahead?
(This was posted on my Facebook notes 2 days ago.)
We’re fast approaching that moment I truly dread – the moment when I have to decide that The Dalles is no longer under “continuous snow cover.” I’m not an official authority on the matter, but decided to appoint myself an unofficial role after reading in the paper that local officials committed a “Late December Flop.” Well not exactly…but they claimed the December snow cover continued unabated into January, something I can attest was NOT true in immediate town.
These are a couple photos of the landscape today: one of the airport region across the river (where snow cover records were kept prior to 2000) and one looking west across the town and the hilly background. There is still too much snow in the “South Hills”, and plenty of snow downtown just about anywhere that the sun isn’t hitting. I’m not going to declare a melt-out today…but if it stays mild overnight into tomorrow we might be in a different place 24 hours from now.
We have some more interesting late-winter weather ahead, but first the short run. There will still be quite a bit of rain in Western Oregon tomorrow and Tuesday, while central California gets deluged by an atmospheric “river” of rain…pray for poor Oroville! Then Wednesday the rain showers taper off as a colder airmass begins to move in.
It now appears clear that we’re going to get one more round of cold, wintry air over the Pacific Northwest beginning Wednesday, and continuing at least through next weekend and likely beyond. A ridge begins to develop and strengthen out in the northern Pacific, and that allows the West Coast to come under the influence of chilly subarctic airmasses from Western Canada and southeastern Alaska. Note that I said “subarctic” instead of arctic…the 850mb temps next Thursday-Sunday are expected to be mainly in the -6 to -8 range for The Dalles. Also…this cold airmass is going to be affected at the lowest levels, to some extent, by the powerful late February sun angle. Because of this, I think high temps in The Dalles late next week could still be 40-42 degrees, assuming at least partly sunny skies. That’s a solid 10 degrees below normal for the last few days of February, though.
If we get a low pressure system to spin up and there’s east wind in the Gorge, it would PROBABLY still be cold enough for snow down to river level. The 18z GFS shows a possibility of this on Thursday night, while some other forecasts show it happening next Sunday. But it’s still too early to tell, especially with these unpredictable “slider lows.” In any case, high temps in the upper 30s / low 40s, and low temps well down in the 20s, for several days in a row will be a clear reminder that spring hasn’t sprung quite yet.
….And now for the REAL drama. Long-range models have, for several days now, been hinting at a truly historic cold blast along the West Coast during the first few days of March. Obviously this is still a long way off, and even in midwinter these maps can go bust with notorious frequency. But both the GFS and the ECMWF have been moderately consistent with the idea of an unseasonably frigid Arctic high-pressure center dropping into BC and Alberta during this timeframe.
I don’t think I’ve ever seen an early March arctic blast so well-advertised on long-range models before. There was an attempt to sneak a surprise blast in during early March of 2014 on the maps, but the cold air backed off a couple days before. The Gorge did get a rare March ice storm out of it, however. But this is more of a “regional” blast rather than a bunch of air spilling over the Rockies and into the Columbia Basin from the east/northeast.
And finally, the CPC is still onboard with a major cold event for the beginning of March:
Add it all up, and it makes for a very exciting end to the winter 2016-17 season. At least this time we can rest assured that something remotely resembling springtime, really *is* not too far behind. We can’t stay in an anomalous cold pattern forever, and our normal daytime high temps are in the mid 50s by the 2nd week of March!