So the secret...is out.
There was much fanfare Wednesday after Seattle tied its all-time warmest November day with our 74 degree high temperature. That goes back to 1945 for Sea-Tac Airport, but Downtown Federal Building records, which go back to 1891, never recorded a warmer November day either.
The record we tied was set November 4, 1949. It was part of what would become the warmest November on record with an average high temperature of 56.17 degrees -- it ended up as warm as October that year.
It begged the question from a few readers -- what was that winter like? After a few seconds, it dawned on me -- that was the start of the harshest winter in Sea-Tac Airport history. As the calendar turned to 1950, region became gripped in a 6-week arctic blast that wiped out nearly every cold temperature record we have -- and almost all of those records stand today as we have yet to have even come close to approaching them since.
Now, let's get in the important asterisk. Yes, that winter was a moderate to strong La Nina winter -- a similar scenario to where we are now. BUT past performance does not guarantee this winter will be the same. It could just be a simple climate coincidence. To wit: The winter that had the second-warmest November daily temperature record (1970) did not have 5 feet of snow the following January. (Although it did have a moderately impressive 9" in January 1971.)
But since the statistic is out there now, and a vast majority of readers were not here to experience that epic winter of 1950, here is what happened:
After the warm November ended, December went pretty close to an average Seattle winter. Temperatures were a little below average, and we had two typical Seattle arctic outbreaks: The three days from Dec. 10-12 featured highs in the mid-upper 30s, lows in the 20s, with a little snow -- 1.8" combined at Sea-Tac. A second cold snap occurred Dec. 18-20 with highs again in the low-mid 30s, but lows were now in the upper teens to mid 20s -- including a low of 17 on Dec. 19. 3 inches of snow fell on the 17th but that was it. The month would recover to typical Seattle rainy, but another cold snap loomed for New Year's Eve as highs dropped back into the 30s, and lows in the 20s, with 1.2" of snow on New Year's Eve.
It was the start of something big.
The 34-day period between Jan. 1 and Feb. 3 had four incredible arctic blasts that crippled the city with several inches of snow and days upon days of bone-chilling temperatures that dropped to single digits overnight.
In fact, 18 of the 34 low temperature records from that time are from 1950 --12 of them in single digits, including the Holy Grail of our cold records, the 0 degree reading on Jan. 31. That stands as the coldest day ever recorded at any official Seattle reading, be it Sea-Tac Airport or the Downtown Federal Building, which kept records from 1891 through 1972.
The average temperature in January was 24.85 degrees -- nearly half of the January we had to begin this year and, you guessed it, the record for coldest January on record.
The appetizer came on New Year's Day when a storm brought nearly 7" of snow to Seattle. After that came the first arctic blast. The high on Jan. 2 was only 24 degrees, and that night, it dropped down to 6. A little more snow fell on the 3rd with another low of 6, then "warming" to 14 for a low on the 4th.
We moderated just a bit for the next week, with highs in the mid-upper 30s and lows near 30 with a little more snow here and there -- about 4" fell on the 8th.
Then, one of the greatest snow storms to strike Seattle hit on the 13th, with 20" of snow amid a high of 19 and a low of 11. Historylink.org says spray from Elliott Bay froze instantly on whatever it landed on the Seattle waterfront. We've also heard stories told of those who had to walk to and from work *up* Queen Anne Hill *both ways* while barefoot and carrying an ox. (Or, so records from some of the city's crotchety grandfathers indicate. ) Low temperature records would fall for the next six days as the snow kept coming, although mostly adding about 1-2" here in spurts.
Seattle abruptly warmed up on the 19th climbing all the way to 42 degrees. The 20th and 21st must have felt like summer with highs of 48 each day and a low of only 42 on the 21st! But it wasn't time to run outside -- it rained quite heavily those days. (Can you imagine the slush?)
After a typical Seattle January rainy 22nd, we started cooling off on the 23rd with even some snow late.
By the 24th, it's back into the ice box with highs in the mid 20s and lows of 10 and 7 for the 24th and 25th, respectively; both records.
The 26th was greeted with another mega snow event -- 10" in Seattle, but surprisingly, not a record low as it "only" cooled to 21. Snow tapered off on the 27th as lows dropped to 19.
And then, as if Seattle hadn't suffered enough that month, came the mini-ice age: A brutal seven-day stretch of single digit lows between Jan. 28 and Feb. 3 (7, 6, 7, 0, 1, 8, 8. -- hey, I think I'll see if I can make that my new cell phone number! Talk about obscure! :) ) But can you imagine the news coverage should that kind of extended arctic blast happen today?!?. Doesn’t look like it snowed much then, so I'm guessing it was one of those blazing sunny but bitter cold Fraser Wind days.
Finally, on Feb. 4, it warmed to 41 and the weather became relatively sane after that.
It appears it had never been cold like 1950 even before that year, stretching back to 1891 Federal Building records. There are only two low temperatures in single digits in the Federal Building records, which, not surprisingly are on Jan. 31 (3 degrees) and Feb. 1 (4 degrees). But! What you might not expect is those dates are from the blizzard of 1893, not from 1950, which means even on the day it hit 0 at Sea-Tac on Jan. 31, 1950, it was warmer than 3 at the Federal Building.
As to what caused this massive, extended arctic outbreak, I gather it was somewhat of a similar set up to the December cold snap we had at the end of 2008 -- a very big ridge of high pressure in the Pacific Ocean just offshore sending the air flow way up into the arctic, then shooting it down from the north into British Columbia. Meanwhile, strong storms were coming in under the ridge and barelling ashore just to our south. And each time a low passed by, it drew in massive amounts of arctic air through the Fraser Valley into Western Washington.
I can only surmise those storms must have been quite massive, and the amount of arctic air in British Columbia was quite intense and deep, and each successive storm just reinforced the arctic air here.
Will these records ever be broken? Hard to say. It is becoming increasingly difficult because as the Seattle area grows, the city creates more of its own heat (since concrete and asphalt absorb the sun's energy better than vegetation/forest, as cities expand, they tend to radiate more heat at night.) So even if you brought identical atmospheric conditions from 1950 to today, the temperatures might not drop as far, meaning 1950 might just get to keep its monopoly on the record book for eons to come.
1950, Day by Day
Here is the day-by-day chart of January and February's weather at Sea-Tac Airport. (Dates higlighted in blue are still current record lows.)