The What Have You Done For Us Lately Winter Outlook Correlators. Dec & Jan Evaluation In.

[Rainshadow]

I have decided to take a different approach for this upcoming winter with the magnificent seven (or is it eight or nine?) and take a look at what has worked better lately (vs historically).  This will start with the winter of 1998-9 (coincidence you say?) and give an 18 season sample size.  Hopefully this is long enough to preclude any one hit wonders but not long enough to keep oldies but no longer goodies viable.

 

So, the first installment comes from last summer when the strongly negative July AO was all the rage because the same happened in July of 2009 and we know what happened that ensuing winter.(Speaking of one hit wonders) Since July 1998 there have been 12 negative AO and 6 positive AO Julys. In the ensuing winters, those with negative Julys averaged positive for the winter eight times and negative for the winter four times.  Contrary to folklore the 6 positive AO Julys saw a sign switch four times and were positive two times. 

 

Grand total last 18 winters, 10 have average a positive AO, 8 have averaged a negative AO.  While historically (oh no!) positive AO(s) have almost always meant a warmer winter (cough, cough 2013-4) , a negative AO has not guaranteed a cold winter.

 

What about this July?  Looks like the AO is going to average very close to neutral (zero), eyeballing looks like weak positive. 

[tombo82685]

I have decided to take a different approach for this upcoming winter with the magnificent seven (or is it eight or nine?) and take a look at what has worked better lately (vs historically).  This will start with the winter of 1998-9 (coincidence you say?) and give an 18 season sample size.  Hopefully this is long enough to preclude any one hit wonders but not long enough to keep oldies but no longer goodies viable.

 

So, the first installment comes from last summer when the strongly negative July AO was all the rage because the same happened in July of 2009 and we know what happened that ensuing winter.(Speaking of one hit wonders) Since July 1998 there have been 12 negative AO and 6 positive AO Julys. In the ensuing winters, those with negative Julys averaged positive for the winter eight times and negative for the winter four times.  Contrary to folklore the 6 positive AO Julys saw a sign switch four times and were positive two times. 

 

Grand total last 18 winters, 10 have average a positive AO, 8 have averaged a negative AO.  While historically (oh no!) positive AO(s) have almost always meant a warmer winter (cough, cough 2014-5) , a negative AO has not guaranteed a cold winter.

 

What about this July?  Looks like the AO is going to average very close to neutral (zero), eyeballing looks like weak positive. 

I also have heard -nao's and July too favoring more blocking. Granted we had some -nao stuff around the blizzard, but for the most part it was non existent despite the -nao last july. 

[Rainshadow]

I also have heard -nao's and July too favoring more blocking. Granted we had some -nao stuff around the blizzard, but for the most part it was non existent despite the -nao last july.

I know they are seasonal index numbers, but they don't corroborate it. Its been the opposite. Regardless this July ao was not strongly negative.

[Mitchg]

I'm not big on the July relation on winter either. 

[tombo82685]

What was last years AO in October? Also read a couple years ago what it does in October correlates pretty well to winter.

[Rainshadow]

What was last years AO in October? Also read a couple years ago what it does in October correlates pretty well to winter.

 

Negative and last winter barely squeaked out a negative index average.

[Qtown Snow]

this winter talk thread has me all hula giddy.

tony, thanks for starting it.

[rramblings]

HI, AO is arctic oscillation? And I can start by read more about this here?: http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/teleconnections.shtml and here: http://climate.ncsu.edu/climate/patterns/NAO.html

 

Thanks.

[NEchestercountydude]

Isn't the AO's base state technically like -0.2 anyways? Thought I read that somewhere.

[Rainshadow]

Inst the AO's base state technically like -0.2 anyways? Thought I read that somewhere.

 

That has been definitely true during the winter since 1950, 41 of 66 winters have averaged a negative ao. When the ao has averaged positive during the winter, 23 of 25 have been warmer than the winter average since 1950.

[tombo82685]

HI, AO is arctic oscillation? And I can start by read more about this here?: http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/teleconnections.shtml and here: http://climate.ncsu.edu/climate/patterns/NAO.html

 

Thanks.

Yup, arctic oscillation. Basically, PV over pole is a + one, PV away from pole is -

[Rainshadow]

The last 18 winters, half have been colder than the current normal (35.4) and half have been warmer.  Its been a 2:1 split with the AO.  When the AO has been negative, the winters have been colder than the current normal twice as often, when the AO has been positive, the winters have been warm twice as often.  Dr. Cohen relates the October Siberian snow cover with the winter AO.

 

Since 1998 for Eurasian snow coverage during October has been above the long term median 13 of 18 times.

 

Above median snow coverage, ensuing winter AO positive 6 of 13 times

Below median snow coverage, ensuing winter AO positive 4 of 5 times 

[KG1]

Thanks for the stats Tony. So a 50/50 chance of a -AO with + snow coverage and 80% chance of a +AO with - snow coverage. I'd say we're getting hosed by the AO.  lol

[Rainshadow]

Thanks for the stats Tony. So a 50/50 chance of a -AO with + snow coverage and 80% chance of a +AO with - snow coverage. I'd say we're getting hosed by the AO.  lol

 

Yes the contrarian coverage has worked better as a predictor of the AO (as well as temps and snowfall) than the Cohen study locally.  I guess on the plus side whether its because of less arctic sea ice (or what it means, more water vapor in the air in general), the "new normal" has been above normal snow coverage in Eurasia by the end of October. While it doesnt guarantee a snowy/cold winter, it does not close the door to it.

[rramblings]

Yup, arctic oscillation. Basically, PV over pole is a + one, PV away from pole is -

 

Thanks!

[tombo82685]

Since Tony will be living in barrow for the winter, maybe he can help push the pv off the pole this winter.

[irishbri74]

Since Tony will be living in barrow for the winter, maybe he can help push the pv off the pole this winter.

Having it over Alaska may be worse than atop the pole!

[KG1]

Since Tony will be living in barrow for the winter, maybe he can help push the pv off the pole this winter.

What's the correlation for Oct snow cover on top of Mt Trappe?

[Rainshadow]

Having it over Alaska may be worse than atop the pole!

 

Too bad, I want to look up and just see cold.

[tombo82685]

Too bad, I want to look up and just see cold.

 

you will push it to Hudson Bay and like it. It will do you good. Instead of -40, it will be -10

[Rainshadow]

What was last years AO in October? Also read a couple years ago what it does in October correlates pretty well to winter.

 

Yes, better, especially that last 9 Octobers.  Was this from Matt Lanza?

 

October AO when positive, 6 of 8 ensuing winter AO have been positive.

October AO when negative, 6 of 10 ensuing winter AO have been negative.

 

This has worked even better recently as 8 of the last 9 winters have followed the October AO signage.

[tombo82685]

Yes, better, especially that last 9 Octobers.  Was this from Matt Lanza?

 

October AO when positive, 6 of 8 ensuing winter AO have been positive.

October AO when negative, 6 of 10 ensuing winter AO have been negative.

 

This has worked even better recently as 8 of the last 9 winters have followed the October AO signage.

I believe it was, saw it on twitter

[Rainshadow]

I was honestly surprised this has worked relatively well since 1998 wrt tempersatures. My opinion was clouded since it was wrong 2 of the last 3 winters. As the research goes, the ssta south of Newfoundland from May thru July is suppose to be the underlying theme that will resurface during the ensuing winter. Negative anomalies support a -nao, positive anomalies a +nao for the ensuing winter.  Problem has been that 14 of the last 18 winters the NAO has averaged positive, while half the winters have averaged cold.

 

+NAO winters, 8 warm, 6 cold...strong Pacific patterns can shove the NAO out of the way.

-NAO winters, 1 warm,  3 cold

 

So on one hand the Newfoundland Pool has not been a great NAO winter predictor, getting it right only 11 of 18 times (61%). 

 

But in spite of that original purpose, its been a better predictor of our temps locally (if you ignore the last three winters).  

 

The pool had an 11 year run of correct temperature directions from 2002-12.

 

The pool is warm, 7 of 9 ensuing winters warmer than normal.

The pool is cool, 7 of 9 ensuing winters colder than normal.

 

Our pool this year was warm.....  Of course since weather like life is messy, a cold pool was not that

far off to the southeast.

 

 

[Rainshadow]

Summarizing so far:

+AO for this July, 67% sign switch for upcoming winter

AO for October (when positive, 6 of 8 ensuing winter positive; negative, 6 of 10 ensuing winter negative) TBD

Newfoundland pool, +nao for winter (8 warm, 6 cold recently...strong Pacific patterns can shove NAO out of the way).

 

Speaking of strong Pacific, this takes us to the Pacific Decadal Oscillation.  When positive (warm waters eastern Pacific), the ensuing winters historically have been cold. Whether its a feedback, result, or initiator of more or longer lasting -epo/+pna patterns am not sure. 

This has still been the case during the past 18 years.  We have had 10 winters that averaged +PDO and 8 winters that have averaged a -PDO.

When positive, 7 of the last 10 of those winters have been colder and snowier than average; when negative 6 of the 8 ensuing winters have been warmer and less snowier than average.

Problem though, unless its way warm or way cool leading into the winter, I have not see too many PDO outlooks.  The good news is that the latest (July) monthly index number is still a relatively high positive (+1.25) value.  It looks like historically if the September and October values stay >1.00, its been a slam dunk that the ensuing winter's PDO will average positive.  Its even worked for +0.8s and +0.9s, but some of those winters have had two negative months that have been outweighed by one positive month.  So anyway, we are starting from a good point.

[tombo82685]

I <3 -epo's in winter