PORTLAND, Ore. (KOIN) — With an arctic blast of frigid temperatures set to inundate the Pacific Northwest next week, we wanted to jump into our historical weather data to see how many temperature records we could possibly break.
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Some of this data might surprise you since it seems like the last two years have brought us nothing but unprecedented and extreme weather events. Last our region endured an icy snowstorm that knocked out power for weeks for some. Record heat in June followed, along with a relentless drought and mega wildfires across the summer months.
The bottom line is that the incoming cold will bring significant impacts to the region, but it is not particularly abnormal. We have gotten this cold plenty of times before.
The Frigid Forecast
Let’s first start with the temperature forecast next week.
Weather models are continuing to showcase an outbreak of arctic air dropping down and sending the PNW into a deep freeze. As we move into Monday, daytime highs will plummet to near or below freezing. By Tuesday, high temperatures in Portland may top out in the upper 20s.
Portland will struggle to reach high temperatures above freezing, possibly until New Year’s weekend.
With a chance to break record-cold highs both Monday and Tuesday next week, Wednesday and Thursday may turn out to be the coldest during our deep freeze.
In the bar graph above, notice how high temps in the 20s and teens have occurred before.
A high of 14-degrees is the current cold record for Thursday, December 30, occurring back in 1968. That also happens to be the coldest daytime high ever recorded in Portland between 1940 to 2019.
What about the duration of sub-freezing high temperatures next week? With Tuesday through Thursday likely locked into a deep freeze, could that break any records?
To no surprise, December of 1972 had a cold stretch of 10 consecutive days of high temperatures below 32 degrees. The record holder for consecutive days with sub-freezing high temperatures is from a 12-day stretch back in January of 1957.
Arctic Blasts of the Past
The cause of a winter cold snap is the amplification of an offshore ridge. Our jet stream soars to the north, allowing for a deepening trough of low pressure to develop over the west coast. As the trough strengthens, it allows cold arctic air to drop down and invade the Pacific Northwest.
When these patterns set up, it can keep daytime high temperatures running 20° below normal around the valley. It primes the valley floor to see snow, even sending snowfall down to sea level and across the Oregon coastline!
How many prominent arctic blasts have we seen in recorded history? Quick shoutout to our KOIN 6 Meteorologist, Steve Pierce, for keeping some of those records. As a Vancouver, Washington native — he has lived and breathed cold snaps for decades.
Going back to data from 1950 to now, Portland has seen over 20 of these “arctic blast” events. Not all of them have provided heavy snowfall in the city. But most — if not all of these events — have caused high temperatures to drop into the teens, 20s, and low 30s.
In terms of frequency, the arctic blasts tend to happen every three to four years in this region.
The Bottom Line
It is going to get cold in Portland.
Models have continued to show impressive forecast temperatures for the week after Christmas. Monday to Thursday next week looks to be the coldest with highs in the 20s and 30s. Few record-cold temps will likely be broken.
Any snow that we see over the holiday weekend may stick around on roadways as we struggle to bump above freezing. Be sure to cover your outdoor spigots to avoid pipes cracking or bursting. Check on loved ones and cozy up in front of the fire.
The KOIN 6 weather team will continue to monitor the forecast going into Christmas weekend as a threat for low elevation snow arrives across the Portland Metro Area.