It was about a week and a half before our November Arctic blast that the forecast simulations I use started hinting at us going into the deep freeze. And although they had trouble nailing the exact timing, they gave us plenty of notice that a weather change was ahead. And boy were they right!
1. Monday November 22: Portland went from rainy and a high near 40 to the deep freeze. By the end of the night, we had .3″ (a third of an inch) of snow at the Portland International Airport, home of our long term records. It’s rare to have any snow accumulate in November, it’s happened less than 10 times on record. The last time it happened was 2003.
2. Monday November 22, part 2: The arctic air raced in so quickly it caused big lift in the atmosphere. This lead to a rare event called “thunder snow” in the eastern metro area. This is a thunderstorm that creates lightning, thunder and you guessed it, snow. What’s most strange to me, though, is how snow muffles the sound of thunder and dims the brightness of lightning. So only those within a 3-4 mile radius of this actually got to see or hear it.
3. Tuesday November 23: Portland’s high is just 30 degrees. That’s the first time the Rose City fails to hit freezing on a November Day in a quarter of a century. Ironically, that was November 23, 1985. The same day, twenty-five years earlier!
4. Wednesday November 24: Portland’s low was 18 degrees. This was the city’s coldest November start in 17 years. And there’s something ironic here. The last time we had a November morning dip to 18 degrees was November 24, 1993. Same day, same low temperatures. And 17 years apart!
Now it looks like we’re going to transition to warmer weather with more mountain snow for the Cascades especially Black Friday. While the Coast Range will be wet. And we’ll have to watch for a possibly icy transition in the Columbia River Gorge (and places nearby) to start Friday morning.