You might call it a snow low.
Cold air is moving to the southwest across the northern BC coast and becoming unstable as it goes over warmer water, producing streaks of instability clouds that circle around the low (indicated by a red "L")
Some of the cold, Arctic air from the interior of BC is moving westward down the Fraser River Valley into Bellingham and its vicinity. At 2 PM, it was only 25F in Bellingham and in the low 20s a few miles away.
To get a big snowstorm over western Washington, we need the low center to park just offshore of the SW Washington coast. This pulls cold air southward over western WA and is close enough to push moisture over it.
Many of our big snow events have occurred that way.
Unfortunately, the model is moving the low too far offshore, as shown by the forecast surface map for 10 PM tonight
There will be some snow tonight with amounts increasing with elevation. Being at 500 or 1000 ft makes a big difference during such situations. For example, Dr. Peter Benda measures about 5 inches of snow at around 1000 ft in Bellevue (see below).
Here is the total predicted snowfall through 4 PM Tuesday. Mostly light amounts except where the Fraser arctic air is hitting the mountains of Vancouver Island or the north side of the Olympics.
This will be one of the most sustained cold periods in years...with the cold holding out for perhaps two more weeks (see below). Just amazingly cold. Historic cold spell.
_____________________________
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Please consider making a contribution (tax-deductible) to this University of Washington fund. And thanks to the hundreds of folks who have already contributed.
Here is the info:
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It appears from the forecast that the average temperature for the first 2 weeks of this month may compare favorably with that of February 2019 in western Whatcom County. It does not appear as though it will be as cold as the first half of the Februaries of 1949 or 1936. For SeaTac, the first half of February 1989 is the gold(cold) standard and it does not appear that it will be as cold as then - more in line with February 2019.
ReplyDeleteThanks as always for keeping us updated and providing us with this information - it always helps me prepare for what's ahead weather wise. I can't help think back to this exact tiime almost to the day about 6 years ago I think??? when we had that February filled with snow, cold temps and then more and more snow....epic times.
ReplyDeleteWow, these models have been so accurate (at least for my location). I have about 5 inches on the ground at 800' on Tiger Mountain, which exactly what the snow depth model predicted. Looking at the 4km (in process right now), and it looks like quite a bit of snow for me tomorrow. Weather Underground app is currently just showing a dusting for tomorrow.
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