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Looks like -AO this winter. What does it mean for us?


Front Ranger

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This thread is for open discussion on the likelihood of a -AO this winter, and what it may or may not mean for the PNW, the West overall, and the hills of Maryland.

 

I'll start things off with a bunch of random, yet relevant facts.

 

- Sep 2016 had moderately +AO (which led to a record fast September freeze up in the Arctic ocean)

- Oct 2016 saw a flip to very -AO, which looks to persist at least for a bit into November

 

 

 

- other years that saw a big flip from Sep to Oct: 1950, 1953, 1980, 1997, 2003, 2004, 2006, 2009, 2012

- Octobers that saw a -.75 or lower AO: 1960, 1966, 1968, 1974, 1976, 1979, 1981, 2002, 2006, 2009, 2012, 2014

- of those Octobers, 1960, 1966, 1968, 1976, 1979, 1981, 2002, 2009, and 2012 (9/12) were followed by -AO winters. And overall, those winters favored cold weather in the east.

 

 

 

- however, 2002 and 2009 were moderate/strong Ninos (we currently have weak/moderate -ENSO)

- we currently have +QBO, which as Phil has explained favors more high latitude blocking, especially with -ENSO

- here's the list of +QBO/neutral or -ENSO/-AO years: 2010, 1985, 1980, 1978, 1966, 1961, 1959

 

 

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This thread is for open discussion on the likelihood of a -AO this winter, and what it may or may not mean for the PNW, the West overall, and the hills of Maryland.

 

I'll start things off with a bunch of random, yet relevant facts.

 

- Sep 2016 had moderately +AO (which led to a record fast September freeze up in the Arctic ocean)

- Oct 2016 saw a flip to very -AO, which looks to persist at least for a bit into November

 

attachicon.gifao.obs.gif

 

- other years that saw a big flip from Sep to Oct: 1950, 1953, 1980, 1997, 2003, 2004, 2006, 2009, 2012

- Octobers that saw a -.75 or lower AO: 1960, 1966, 1968, 1974, 1976, 1979, 1981, 2002, 2006, 2009, 2012, 2014

- of those Octobers, 1960, 1966, 1968, 1976, 1979, 1981, 2002, 2009, and 2012 (9/12) were followed by -AO winters. And overall, those winters favored cold weather in the east.

 

attachicon.gif-ao.png

 

- however, 2002 and 2009 were moderate/strong Ninos (we currently have weak/moderate -ENSO)

- we currently have +QBO, which as Phil has explained favors more high latitude blocking, especially with -ENSO

- here's the list of +QBO/neutral or -ENSO/-AO years: 2010, 1985, 1980, 1978, 1966, 1961, 1959

 

attachicon.giffff.png

 

One thing to point out is 1985-86 was a fantastic winter, but the best stuff was in Nov which isn't captured by the map.  2010, 1978, 1961, and 1959 were all decent to very good.

Death To Warm Anomalies!

 

Winter 2023-24 stats

 

Total Snowfall = 1.0"

Day with 1" or more snow depth = 1

Total Hail = 0.0

Total Ice = 0.2

Coldest Low = 13

Lows 32 or below = 45

Highs 32 or below = 3

Lows 20 or below = 3

Highs 40 or below = 9

 

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So... Bastardi might be onto something again with cold focused in the east.

Looks focused mostly in the Central US to me, which I think is reasonable.

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One thing to point out is 1985-86 was a fantastic winter, but the best stuff was in Nov which isn't captured by the map.  2010, 1978, 1961, and 1959 were all decent to very good.

 

True. If November is included, the cold departures are pretty evenly distributed.

 

 

 

All in all, those winters featured a grand total of 8 major Arctic outbreaks for the PNW by my count. And only 2 of the winters were truly east-focused: 1966-67 and 1980-81.

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True. If November is included, the cold departures are pretty evenly distributed.

 

attachicon.gif12.png

 

All in all, those winters featured a grand total of 8 major Arctic outbreaks for the PNW by my count. And only 2 of the winters were truly east-focused: 1966-67 and 1980-81.

 

 

I doubt we are looking at 1985-esque November.   

**REPORTED CONDITIONS AND ANOMALIES ARE NOT MEANT TO IMPLY ANYTHING ON A REGIONAL LEVEL UNLESS SPECIFICALLY STATED**

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Looks focused mostly in the Central US to me, which I think is reasonable.

 

One thing I question is whether it will be so cold in the SE.  Not favored with a Nina at all.  I could see a situation where most if not all of the north could end up cold though.  I think the SE will be key for us.  If there is a SE ridge during a major -AO episode the cold could easily be focused NC and NW.

Death To Warm Anomalies!

 

Winter 2023-24 stats

 

Total Snowfall = 1.0"

Day with 1" or more snow depth = 1

Total Hail = 0.0

Total Ice = 0.2

Coldest Low = 13

Lows 32 or below = 45

Highs 32 or below = 3

Lows 20 or below = 3

Highs 40 or below = 9

 

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True. If November is included, the cold departures are pretty evenly distributed.

 

attachicon.gif12.png

 

All in all, those winters featured a grand total of 8 major Arctic outbreaks for the PNW by my count. And only 2 of the winters were truly east-focused: 1966-67 and 1980-81.

 

That map has a nice look to it.

Death To Warm Anomalies!

 

Winter 2023-24 stats

 

Total Snowfall = 1.0"

Day with 1" or more snow depth = 1

Total Hail = 0.0

Total Ice = 0.2

Coldest Low = 13

Lows 32 or below = 45

Highs 32 or below = 3

Lows 20 or below = 3

Highs 40 or below = 9

 

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One thing I question is whether it will be so cold in the SE. Not favored with a Nina at all. I could see a situation where most if not all of the north could end up cold though. I think the SE will be key for us. If there is a SE ridge during a major -AO episode the cold could easily be focused NC and NW.

I'm thinking February has the best shot at featuring a more persistent SE ridge, otherwise I think it'll be a sporadic, intermittent feature. Not that it matters what I think, of course.

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I doubt we are looking at 1985-esque November.   

 

Very doubtful. Also doubtful we are looking at a 1978-79 winter nationally. But 1985 was not the only winter on that list with Arctic air in November, couple others as well.

 

Regardless, I think it's clear that -AO is favored this winter, -AO means better chance of significant Arctic outbreaks in the lower 48, and +QBO/-ENSO has been a pretty good combo for the PNW.

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Very doubtful. Also doubtful we are looking at a 1978-79 winter nationally. But 1985 was not the only winter on that list with Arctic air in November, couple others as well.

 

Regardless, I think it's clear that -AO is favored this winter, -AO means better chance of significant Arctic outbreaks, and +QBO/-ENSO has been a pretty good combo for the PNW.

Agree. Just need to get the tropical forcings and hemispheric AAM integral resynchronized into Niña mode. At that point, we'll start seeing NPAC ridging blow up fairly quickly, IMO.

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It is interesting to note 1968-69 was perhaps the most extreme minus AO winter on record.  Obviously it was a Nino, but it makes me wonder if want to see an ultra -AO as opposed to a more traditional -AO winter.

Death To Warm Anomalies!

 

Winter 2023-24 stats

 

Total Snowfall = 1.0"

Day with 1" or more snow depth = 1

Total Hail = 0.0

Total Ice = 0.2

Coldest Low = 13

Lows 32 or below = 45

Highs 32 or below = 3

Lows 20 or below = 3

Highs 40 or below = 9

 

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It is interesting to note 1968-69 was perhaps the most extreme minus AO winter on record.  Obviously it was a Nino, but it makes me wonder if want to see an ultra -AO as opposed to a more traditional -AO winter.

 

That honor goes to 1976-77.

 

But if you can get -PNA with -AO, you're pretty much golden. See: 1955-56, 1968-69, 1978-79, 1979-80, 1985-86, Dec 1996, Nov 2010. 1968-69 stands out as the only Nino, but it was weak. I guess 1979-80 is technically classified as a Nino now as well.

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That honor goes to 1976-77.

 

But if you can get -PNA with -AO, you're pretty much golden. See: 1955-56, 1968-69, 1978-79, 1979-80, 1985-86, Dec 1996, Nov 2010. 1968-69 stands out as the only Nino, but it was weak. I guess 1979-80 is technically classified as a Nino now as well.

 

No accident both 1968-69 and 1976-77 were historic winters somewhere in the US as far as cold is concerned.  I guess we want to go with extreme minus AO then.

Death To Warm Anomalies!

 

Winter 2023-24 stats

 

Total Snowfall = 1.0"

Day with 1" or more snow depth = 1

Total Hail = 0.0

Total Ice = 0.2

Coldest Low = 13

Lows 32 or below = 45

Highs 32 or below = 3

Lows 20 or below = 3

Highs 40 or below = 9

 

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No accident both 1968-69 and 1976-77 were historic winters somewhere in the US as far as cold is concerned.  I guess we want to go with extreme minus AO then.

 

Yeah, I don't think it could hurt with -ENSO/+QBO. That being said, there have been many great PNW winters with neutral or +AO, but if you're going to get -AO, no reason not to root for extreme.

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Regarding Eurasian snowcover advance, here's all years since 1966 ordered from least o greatest SAI, color coded by ENSO:

 

Looks like 2016 is 3rd highest on record:

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/464203A5-BF54-4ED2-A4F9-DDA6CF3CDB7E_zpsedyo70yq.png

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Interestingly enough, that year did not have a -AO October. But it did go on to be moderately -AO in winter.

Yeah sometimes intraseasonal forcing and/or waveguide cycles misalign, timing wise.

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Even more interesting, all of the Niña years with expansive Eurasian snowcover featured -QBOs, unlike this year which is running an entrenched +QBO Figures.

 

I guess the closest Niña/+QBO snowcover match would be 2010/11.

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November following in October's -AO ways so far...

Following October's significant -AO, if November's AO averages near/below -0.5, the odds of a warm winter nationally drop to near-zero in all weak/neutral ENSO winters regardless of QBO or ENSO sign.

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Just to rehash, the October AO came in at -1.917, smashing the previous record of -1.540 set back in 2009. No Niña years come anywhere close to this.

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/3D431830-8E55-4AB9-8134-D98AF507D522_zpsyc2a7gho.png

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Just to rehash, the October AO came in at -1.917, smashing the previous record of -1.540 set back in 2009. No Niña years come anywhere close to this.

 

The fact this happened with a Nina is very intriguing. Kind of in uncharted waters.

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Death To Warm Anomalies!

 

Winter 2023-24 stats

 

Total Snowfall = 1.0"

Day with 1" or more snow depth = 1

Total Hail = 0.0

Total Ice = 0.2

Coldest Low = 13

Lows 32 or below = 45

Highs 32 or below = 3

Lows 20 or below = 3

Highs 40 or below = 9

 

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Share on other sites

The fact this happened with a Nina is very intriguing. Kind of in uncharted waters.

For better or for worse it does look interesting. 

Winter 23-24: Total Snow (3.2")    Total Ice (0.2")     Coldest Low: 1F     Coldest High: 5F

Snow Events: 0.1" Jan 5th, 0.2" Jan 9th, 1.6" Jan 14, 0.2" (ice) Jan 22, 1.3" Feb 12

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For better or for worse it does look interesting. 

 

Yeah, it's tricky because 1) we know -ENSO tends to favor more cold in the west, and 2) -AO does not necessarily favor the West for cold, if anything it favors areas further east more, even with -ENSO.

 

But, again going back to the first post, I think when you consider we have -ENSO, +QBO, and -AO (assuming the fall correlation holds true), you have to be optimistic for blocking that will at least favor the West at times. And whatever cold shots do occur could be quite significant.

 

Looking at those neutral/-ENSO, +QBO, -AO years again: 2010, 1985, 1980, 1978, 1966, 1961, 1959. October 2016 was nothing like 1966 or 1980 (both were cool nationally). It was also nothing like 1985 or 1961, which were quite cool throughout the West. 2010 is really the only good match, although 1978 also was pretty torchy for the West, fwiw.

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Here's all the -ENSO years that were nationally a good to decent match to 2016 in October: 1950, 1955, 1962, 1973, 1983, 1998, 2005, and 2010.

 

Of those, only 2010, 1973 and 1955 are good QBO matches...and all of those were strong Ninas. So yeah, this year continues to be an enigma. However, 1955 and 2010 both had -AO signal as well, and both produced major blasts in Nov and Feb.

 

Overall, I'd have to say the best analogs are: 1950, 1955, 1959, 1966, 1978, and 2010. 

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Here's all the -ENSO years that were nationally a good to decent match to 2016 in October: 1950, 1955, 1962, 1973, 1983, 1998, 2005, and 2010.

 

Of those, only 2010, 1973 and 1955 are good QBO matches...and all of those were strong Ninas. So yeah, this year continues to be an enigma. However, 1955 and 2010 both had -AO signal as well, and both produced major blasts in Nov and Feb.

 

Overall, I'd have to say the best analogs are: 1950, 1955, 1959, 1966, 1978, and 2010. 

Interestingly enough models seem to be moving towards the potentially for a good to great blast of cold air in about 2 weeks. Todays 12z GEM control showed something that might rival Nov 2010. Certainly something to watch, especially with that as a good analog. 

Winter 23-24: Total Snow (3.2")    Total Ice (0.2")     Coldest Low: 1F     Coldest High: 5F

Snow Events: 0.1" Jan 5th, 0.2" Jan 9th, 1.6" Jan 14, 0.2" (ice) Jan 22, 1.3" Feb 12

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Interestingly enough models seem to be moving towards the potentially for a good to great blast of cold air in about 2 weeks. Todays 12z GEM control showed something that might rival Nov 2010. Certainly something to watch, especially with that as a good analog.

Yeah...the GEM control has been going for ultra tanked PNA later in the month. Going to be interesting I think.

Death To Warm Anomalies!

 

Winter 2023-24 stats

 

Total Snowfall = 1.0"

Day with 1" or more snow depth = 1

Total Hail = 0.0

Total Ice = 0.2

Coldest Low = 13

Lows 32 or below = 45

Highs 32 or below = 3

Lows 20 or below = 3

Highs 40 or below = 9

 

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