Best historical matches to recent cold waves

[wx_statman]

So, I've been playing with ECMWF ERA5 reanalysis data for 1950-2021. I thought it would be fun to go through some recent cold waves and find their closest historical analogs. The criteria here is the spatial pattern of 500mb GPH between 40-60N, and 140-110W. The magnitude of the actual heights won't be the same especially if a similar pattern occurred in a different season.

For each pattern, I will list the date which I am trying to match (in bold), followed by its closest historical matches (in order of best match):

12/27/2021 --> 1/2/1950, 2/13/1990, 2/22/2018, 11/21/2003, 5/23/2004

2/12/2021 --> 6/23/1993, 11/28/1985, 9/22/1955, 9/24/1986, 5/14/1986

10/25/2020 --> 12/29/1990, 4/19/1966, 11/24/2010, 12/12/1967, 3/26/1970

3/14/2020 --> 6/6/1980, 1/2/2017, 2/9/2019, 9/16/1954, 11/10/1985

2/26/2019 --> 4/22/2008, 11/19/1978, 12/31/1992, 10/6/1957, 1/9/2005

2/9/2019 --> 4/28/2009, 1/8/1993, 8/28/1951, 1/2/2017, 12/6/1972

1/10/2017 --> 7/29/2013, 2/13/2000, 11/11/1965, 12/13/2016, 8/10/2005

11/13/2014 --> 1/15/1957, 4/27/1958, 4/30/2009, 6/14/1969, 12/23/1983

2/6/2014 --> 6/27/1959, 5/24/2012, 5/11/2000, 5/3/1996, 3/4/2019

12/7/2013 --> 12/20/1998, 9/30/1950, 12/8/2009, 12/20/1990, 12/7/1972

1/17/2012 --> 1/3/1982, 4/1/2008, 11/9/1995, 11/4/1990, 10/26/1971

2/25/2011 --> 1/20/1962, 1/3/1974, 1/5/1993, 3/21/1954, 2/17/1993

11/23/2010 --> 1/14/1950, 10/27/1971, 12/27/2021, 1/3/1973, 1/2/1950

Some notes:

-The patterns on 1/2/2017, 2/9/2019, and 3/14/2020 were all historically very similar, despite 72 years of patterns to choose from.

-The November 2010 blast had two of its closest matches from January 1950!

-February 12, 2021 was a weird one. 4/5 best matches were in the warm season, along with Nov. 1985 thrown in.

-December 2013 was in legit company! Interesting that some of the biggest December blasts on record had very similar patterns. In fact, 4/5 best matches were from December despite having the entire calendar to choose from.

 

[BLI snowman]

Interesting stuff, thanks for sharing.

Curious where January 13-15, 2020 falls on the list. If we were restricting that to DJF analogs then I would think perhaps early December 1980 or early January 1966 would be there.

Edited May 13, 2022 by BLI snowman

[wx_statman]

5 minutes ago, BLI snowman said:

Interesting stuff, thanks for sharing.

Curious where January 13-15, 2020 falls on the list. If we were restricting that to DJF analogs then I would think perhaps early December 1980 or early January 1966 would be there.

No problem! Some of those were surprising, but others I kinda figured. Jan 13-15, 2020 is interesting. The 13th mostly matches to warm season patterns (best match is 10/24/1991 right before the big pre-Halloween blast), and the best DJF matches are 2/24/1956 and 2/23/2011. The 14th is all over the place - best match is 9/19/1988 followed by 11/8/2000. Best DJF matches are 12/18/1951 and 1/9/1950. The latter is obviously in a transition to what would become a major cold wave. Similar story for the 15th. Oddly enough, the best matches are all from the warm season (7/23/1953, 7/2/2002, 6/16/2001, 6/23/1981). The closest DJF matches are 2/28/1976 (heading into a major maritime blast), 1/23/1965, and 1/22/1954 (another epic onshore snow pattern). However, one of the best matches to 1/22/1954 is 12/2/1980 so you nailed that one, they are clearly very closely related.

[BLI snowman]

7 minutes ago, wx_statman said:

No problem! Some of those were surprising, but others I kinda figured. Jan 13-15, 2020 is interesting. The 13th mostly matches to warm season patterns (best match is 10/24/1991 right before the big pre-Halloween blast), and the best DJF matches are 2/24/1956 and 2/23/2011. The 14th is all over the place - best match is 9/19/1988 followed by 11/8/2000. Best DJF matches are 12/18/1951 and 1/9/1950. The latter is obviously in a transition to what would become a major cold wave. Similar story for the 15th. Oddly enough, the best matches are all from the warm season (7/23/1953, 7/2/2002, 6/16/2001, 6/23/1981). The closest DJF matches are 2/28/1976 (heading into a major maritime blast), 1/23/1965, and 1/22/1954 (another epic onshore snow pattern). However, one of the best matches to 1/22/1954 is 12/2/1980 so you nailed that one, they are clearly very closely related.

 

Thanks. Can definitely see how the relative lack of big offshore amplification is a theme with many of those, perhaps also why most of the best direct analogs are from the warm season months when that muted amplification is more the norm with the mid latitude patterns.

[wx_statman]

3 minutes ago, BLI snowman said:

 

Thanks. Can definitely see how the relative lack of big offshore amplification is a theme with many of those, perhaps also why most of the best direct analogs are from the warm season months when that muted amplification is more the norm with the mid latitude patterns.

Yeah, that makes a lot of sense. BTW you might get a kick out of this - I ran a pattern match for the June 2021 heat dome and one of the best matches was 1/18/2009. It's pretty uncanny how similar those patterns were at the 500mb level.

[BLI snowman]

20 minutes ago, wx_statman said:

Yeah, that makes a lot of sense. BTW you might get a kick out of this - I ran a pattern match for the June 2021 heat dome and one of the best matches was 1/18/2009. It's pretty uncanny how similar those patterns were at the 500mb level.

I definitely remember the 2009 ridge being pretty unreal in terms of amplitude. Fairbanks got into the 50s with that in mid January. 

[jcmcgaffey]

3 hours ago, wx_statman said:

Yeah, that makes a lot of sense. BTW you might get a kick out of this - I ran a pattern match for the June 2021 heat dome and one of the best matches was 1/18/2009. It's pretty uncanny how similar those patterns were at the 500mb level.

This is really interesting thanks for posting. I naturally read this as July 2009 which at first would make sense from a temp standpoint but interesting that the better match was January 2009.   Must just be a coincidence they are the same year. 

[wx_statman]

8 minutes ago, jcmcgaffey said:

This is really interesting thanks for posting. I naturally read this as July 2009 which at first would make sense from a temp standpoint but interesting that the better match was January 2009.   Must just be a coincidence they are the same year. 

Yeah, I see how that might jump out. But January was the better match. June 2021 was extraordinary in many ways, one of which was the extreme amplification/cutoff blocking setup for a summer heat wave. Our biggest summer heat waves are traditionally open ridges that are centered further south. All of the best pattern matches I saw for June '21 were from non-summer months!

[wx_statman]

One of the cool things about doing this pattern matching is finding "hidden" analogs during the warm season. When the right synoptic pattern sets up - one that might cause a historic arctic blast during the winter - but doesn't produce any notable weather because it occurred at the wrong time of year.

Here's a good example. A nice arctic pattern set up on May 24, 2017, with a large, deep trough well positioned to deliver major arctic air to the PNW. But... it was late May and Portland had a 66/49 day. You can definitely see that a colder airmass moved through by looking at daily PDX max/min:

21st: 83/52

22nd: 91/56

23rd: 84/52

24th: 66/49

25th: 75/49

26th: 83/52

27th: 89/56

Some of the best pattern matches to May 24, 2017 during the cold season since 1950 include:

3/3/1955

12/15/1964

1/9/1963

2/14/1956

11/26/1985

 

[wx_statman]

Quick technical note about some of the dates I've given in this thread - the ERA5 reanalysis is set to UTC time so the days are actually 5pm-5pm PST. This might result in some of the provided dates actually reflecting the pattern on the previous day.

[Meatyorologist]

7 hours ago, wx_statman said:

Yeah, that makes a lot of sense. BTW you might get a kick out of this - I ran a pattern match for the June 2021 heat dome and one of the best matches was 1/18/2009. It's pretty uncanny how similar those patterns were at the 500mb level.

That is so cool! Wow!

[Meatyorologist]

January 2009 was also the month that some Cascade stations hit the low-mid 70s. Paradise reached 65°F on the 16th. Wild ridging for winter. The lowlands remained trapped in a foggy inversion, so KSEA ironically ran nearly a -4°F on the month, and had a couple 39°F days in the midst of that death ridging.

Then July 2009 came along and another massive ridge popped up. Though not as amplified or well placed as the wintertime one. KSEA set a new all time record of 103°F.

[wx_statman]

8 hours ago, Meatyorologist said:

January 2009 was also the month that some Cascade stations hit the low-mid 70s. Paradise reached 65°F on the 16th. Wild ridging for winter. The lowlands remained trapped in a foggy inversion, so KSEA ironically ran nearly a -4°F on the month, and had a couple 39°F days in the midst of that death ridging.

Then July 2009 came along and another massive ridge popped up. Though not as amplified or well placed as the wintertime one. KSEA set a new all time record of 103°F.

Yeah, the warmth in the thermal belt was unreal with that one. A couple stations were 78°F if I recall from memory in the 3,000-4,000 foot elevation zone. Some RAWS stations near Brookings were into the 80s with downsloping. The Gorge had a major windstorm with HWW criteria gusts extending into Gresham which is really rare.

[Black Hole]

Nice info here! Thanks for sharing. 

[Doinko]

Thanks for sharing this! I have a question, what did the mini snow event in January 2016 match up to? I think the 500mb pattern during that wasn't really conventional.