Dr Cohen & others offer views on Siberian snow theory..

[bkviking]

This is Bloomberg article with Dr Cohen's first response to how his theory worked out.

We did end up with significant blocking - just not where he stated it would be.

http://www.bloomberg.com/news/articles/2015-03-04/siberian-snow-cover-theory-proves-less-than-perfect-this-winter

This post has been promoted to an article

[Absolute Humidity]

-EPO +PDO +PNA got the job done for the eastern US but Europe being more AO NAO dependant didn't work out so well. One would think that if SAI was a strong correlation to AO blocking that the second most SAI year on record would al least produce an average -AO. I guess not. Still lots of research to do here.

[GaWx]

The SAI as it is currently defined was obviously a huge bust. Granted, I did have a concern for the enormous amount of melting that occurred over about the last four days of October but I was then reassured not to worry because the SAI formula is based on a regression rather than a simple subtraction of 10/31 minus 9/30 or some other simpler formula. (See 10/2014 snowcover thread for all of these posts). So, based on the regression based formula, 2014-5 will have to go down as a colossal failure. I mean I don't know how it could have done worse. The formula suggested a strongly -AO and it was a solid +AO.

Now, perhaps the next ten years will be near perfect. Who knows? However, this will lower my confidence for the formula's predictability for next winter's AO. How could it not ?

[donsutherland1]

-EPO +PDO +PNA got the job done for the eastern US but Europe being more AO NAO dependant didn't work out so well. One would think that if SAI was a strong correlation to AO blocking that the second most SAI year on record would al least produce an average -AO. I guess not. Still lots of research to do here.

Decent article. I strongly agree with the idea that there is a lot of research that remains to be done.

 

The SAI was shaky last winter and did very poorly this winter (final data: DJF average: +0.813; Days Positive: 76%). Given the earlier outcomes, the advance of Eurasian snowcover during October is one component of forecasting the predominant winter state of the AO. However, the correlation is weaker and possibly substantially weaker than had earlier seemed to be the case. Is the SAI qualitatively better than climatology? I don't have the SAI statistics for all winters since 1950 to make a conclusion one way or another (I hope it is, even with the big setback this winter), but that's among the questions that need to be asked. What other element or elements should be included to arrive at more skillful forecasts i.e., Arctic sea ice anomalies, late October changes/reversals in Eurasian snowcover, etc., should also be part of the discussion.

[Absolute Humidity]

Decent article. I strongly agree with the idea that there is a lot of research that remains to be done.

 

The SAI was shaky last winter and did very poorly this winter (final data: DJF average: +0.813; Days Positive: 76%). Given the earlier outcomes, the advance of Eurasian snowcover during October is one component of forecasting the predominant winter state of the AO. However, the correlation is weaker and possibly substantially weaker than had earlier seemed to be the case. Is the SAI qualitatively better than climatology? I don't have the SAI statistics for all winters since 1950 to make a conclusion one way or another (I hope it is, even with the big setback this winter), but that's among the questions that need to be asked. What other element or elements should be included to arrive at more skillful forecasts i.e., Arctic sea ice anomalies, late October changes/reversals in Eurasian snowcover, etc., should also be part of the discussion.

I think one area of study that may prove underestimated and thus may save the day for SAI are the effects of late season recurving Pac typhoons during the late fall when winter patterns begin to setup. Last season, 2013/14 there were two large recurving systems in late Nov early Dec that may have had detrimental effects on the PV that was suppose to be very consolidated and strong during the winter months. These wild cards, the first typhoon and more importantly, the second may have prevented the PV from fully consolidating due to the reinforcing shot from the second, despite Dec being AO positive the effects down stream were lasting. As we all know, last season ended up being almost dead on neutral AO wise. This year we had Nuri recurve at nearly the worst time in Nov. It's effects on the PV were catastrophic but only temporarily as it had plenty of time to recover during the crucial month of Dec without a reinforcing disturbance, and thus set the stage for overall +AO. It will be interesting to see if any research is done on these cause and effect wild cards.

[bkviking]

Boston Globe interview with Cohen who is taking credit for northeast winter.

http://www.bostonglobe.com/lifestyle/2015/03/17/snowpredictor/dcN8CVPxGrGiyfWRwEJnNI/story.html

[AvantHiatus]

The failure of the Siberian Snow Theory proves that we are in uncharted waters across the board in regards to synoptic setups and climate.

[ma blizzard]

Boston Globe interview with Cohen who is taking credit for northeast winter.

http://www.bostonglobe.com/lifestyle/2015/03/17/snowpredictor/dcN8CVPxGrGiyfWRwEJnNI/story.html

he was right for the wrong reasons .. I'm still waiting for the SSW from january and a flip to -AO / -NAO .. he got lucky the -EPO / +PNA bailed him out

[Bob Chill]

The Boston Globe article ticks me off a bit. Taking credit for SAI and cold temps in the east is embarrassing from what the science behind the index represents. The AO raged positive door to door. A total punch in the face from what was supposed to happen. Cohen should admit it. It was a complete failure this year. He's dumbing it down because he can get away with it to save face in what is basically an epic failure. Last year was no shining star either.

[Absolute Humidity]

That was a feel good article completely omitting the step down effects of what eurasian snow cover is theorized to do: promote a -AO base state. It's one thing to high five each other for getting temps and precip and snowfall correct but it's also ones responsibility to admit what went wrong and what went right for the wrong reasons. One thing I believe we all should take away from the last two winters is that the pacific is the true dominant force at play here.

[Isotherm]

That was a feel good article completely omitting the step down effects of what eurasian snow cover is theorized to do: promote a -AO base state. It's one thing to high five each other for getting temps and precip and snowfall correct but it's also ones responsibility to admit what went wrong and what went right for the wrong reasons. One think I believe we all should take away from the last two winters is that the pacific is the true dormant force at play here.

 

 

Agree. While it's possible that the snow cover could help enhance blocking in the EPO domain, that isn't what was theorized. It is a correlation which should fail from time to time, as nothing in meteorology provides us with 100% 1:1 correlations. Some years won't work out. However, this does show that there are other variables which can supercede high snow cover / expansion scenarios. Can't just take one correlation (e.g. the SAI) and forecast a -AO. I think numerous factors need to be analyzed and weighted in the determination of each index modality forecast.

[JC-CT]

Can't really expect them to be teaching meteorology at Columbia Journalism School.

 

But even Cohen admits that he is a  .

[GaWx]

The very strong +AO/+NAO pattern this winter when the Siberian snow signal was indicating otherwise

was probably related to the changes in the North Atlantic.

 

http://www.meltfactor.org/blog/

 

While global surface temperatures are increasingly dominated by warm anomalies, a conspicuous area of cold has persisted south of Greenland and Iceland visible at the ocean surface in sea surface temperature observations. The abnormal cold there has been more anomalous than the US northeast winter. While the most recent northern winter was the warmest on record globally, the ocean surface area south of Greenland & Iceland had the lowest temperatures in the 136 year record. How could this be?

 

 

 Maybe that cold water has been due to cold air over it? Chicken/egg thing? Just brainstorming.

[ORH_wxman]

Yeah, the colder SST's go together with the lower pressures associated with the +AO/+NAO.

The Siberian snow signal scientists probably need to talk to the weakening AMOC researchers.

 

Winter15NOAA.jpg

People probably would have called you insane if you predicted a record cold SST cool south of Greenland a few years ago based on how warm it had been up there in the 2005-2012 period.

 

 

The AMOC (and somewhat related AMO) probably hold a lot of answers to some of the internal climate variability mechanisms...unfortunately we don't have the best understanding of them. It's an interesting area of research that hopefully evolves more over the next decade. It's probably another influential variable in addition to just the snow cover.

[Absolute Humidity]

Yeah, the colder SST's go together with the lower pressures associated with the +AO/+NAO.

The Siberian snow signal scientists probably need to talk to the weakening AMOC researchers.

 

Winter15NOAA.jpg

Interesting as a lot of research as shown the AMOC slowing fairly steadily over the last ten years. Not exactly day after tomorrow or Younger Drius stuff but certainly a point of interest. Nice find BTW.

[scottmartin49]

 Maybe that cold water has been due to cold air over it? Chicken/egg thing? Just brainstorming.

Flow from under the Arctic. Increased temps in the mid-latitudes increase flow rates of oceanic currents; warmer water rushing past Scandinavia forces Arctic water down the Davis and etc., surfacing and pooling where it does. Same thing going on in the Pacific, with the even more violent changes brought about by basin wide mid-level warming. Just look for the areas of relative average ice increase/decrease to locate the currents...

 

Sometimes it helps to forget climatology/meteorology and just consider the whole thing as a simple problem of thermodynamics.

[Drz1111]

Can't really expect them to be teaching meteorology at Columbia Journalism School.

 

But even Cohen admits that he is a  .

Actually, GISS offers a joint masters program with Columbia Journalism School that does just that. 

[Drz1111]

Interesting as a lot of research as shown the AMOC slowing fairly steadily over the last ten years. Not exactly day after tomorrow or Younger Drius stuff but certainly a point of interest. Nice find BTW.

 

 

Meh, Rahmsdof and Mann are hacks.  There's precious little evidence that they're seeing anything that isn't normal multidecadal varation.  Mann would see a hockey stick if he was doing a topographic transect of the central valley. 

[Absolute Humidity]

Meh, Rahmsdof and Mann are hacks.  There's precious little evidence that they're seeing anything that isn't normal multidecadal varation.  Mann would see a hockey stick if he was doing a topographic transect of the central valley.

Same could be said about Cohen and SAI SCE but no one's calling him a hack, just yet. Point is 10 years 50 years, the data sets are tiny compared to the AMOC's 400-800 year cycle.

[Absolute Humidity]

No doubt that we are seeing some very unusual AMOC behavior for this era.

 

http://www.nature.com/ncomms/2015/150224/ncomms7346/full/ncomms7346.html

 

 

An extreme event of sea-level rise along the Northeast coast of North America in 2009–2010

• Paul B. Goddard,
• Jianjun Yin,
• Stephen M. Griffies
• & Shaoqing Zhang

• Affiliations
• Contributions
•  

The coastal sea levels along the Northeast Coast of North America show significant year-to-year fluctuations in a general upward trend. The analysis of long-term tide gauge records identified an extreme sea-level rise (SLR) event during 2009–10. Within this 2-year period, the coastal sea level north of New York City jumped by 128 mm. This magnitude of interannual SLR is unprecedented (a 1-in-850 year event) during the entire history of the tide gauge records. Here we show that this extreme SLR event is a combined effect of two factors: an observed 30% downturn of the Atlantic meridional overturning circulation during 2009–10, and a significant negative North Atlantic Oscillation index. The extreme nature of the 2009–10 SLR event suggests that such a significant downturn of the Atlantic overturning circulation is very unusual. During the twenty-first century, climate models project an increase in magnitude and frequency of extreme interannual SLR events along this densely populated coast.

 

http://tropical.atmos.colostate.edu/forecasts/2013/nov2013/nov2013.pdf

 

 

By Philip J. Klotzbach1 and William M. Gray2

 

The AMO/THC appears to have undergone a significant weakening followed by a re- strengthening over the past several months. The AMO/THC was quite strong during the first three months of 2013 according to our E. ATL metric, then weakened dramatically during the spring (Figure 35). Values in May/June were the lowest observed in the Atlantic basin since 1950. However, these values soon rebounded and were back above normal by July. Despite the rapid re-strengthening of the AMO/THC during the summer of 2013, it appears that the lagged impact of the sudden weakening during the spring months was partially responsible for the much weaker than anticipated Atlantic hurricane season this year.

Clearly seen here below. It will be interesting, perhaps unprecedented if a weakening event is underway now.

Figure 2: This graph shows yearly sea level rise along the northeast North American coast in millimeters per year. The red bar shows how extreme the spike was in 2009. The extreme spike lasted into 2010. Credit: Paul Goddard/University of Arizona Department of Geosciences.