Just finished up my presentation for OMSI tomorrow; I wrap up the past year’s worth of weather before the forecasters stick their necks out (for the meteorological guillotine?). Made a new graphic this time, showing the coldest winter high temp at PDX:
You can pick out the years where we saw a big intrusion of cold arctic air here into the Pacific Northwest. I figure if the high temp was 30 or below it counts, especially if the lows were down in the teens.
I would say there have been 4 real “big freezes” the past 20+ years: December 1990, late January 1996, December 1998, and December 2009. All of these involved several days of high temps well below freezing or extremely cold nights (in the case of 2009).
The Dec 1990 and Jan/Feb 1996 events were especially cold; 3 days of highs 19-21 in 1990, and 5 days below 30 degrees in 1996. The 2009 event saw no snow cover and totally sunny skies, allowing high temps to reach 30-34 each day, a little warmer than those other events. The 2 other events on the chart above? January 2004’s cold only extended down into far northern Oregon and didn’t last too long. December 1998 was pretty cold, but no real strong east wind and it went out with a whimper. Dec 2008 was mainly about the snow…we never had a several days long string of sunny and cold weather, so cold-wise it wasn’t that severe.
For region-wide severity, I would rank them this way:
- Dec 1990
- Dec 1998 (widespread)
- Jan/Feb 1996 (#2 if we’re talking Portland area only)
- Dec 2009
That shows how rare a BIG FREEZE really is here in the Pacific Northwest. We only get a big one every 5-8 years I suppose. We haven’t seen any “arctic action” for 3 winters, but it would not be unusual if we went another winter or two without it.
So what do YOU think? That’s what the comments are for.
Chief Meteorologist Mark Nelsen