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December 2022


dmillz25
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1 hour ago, LibertyBell said:

How well can they predict where the extreme blocking will show up from year to year? I'm guessing not well?

 

They can’t since model skill quickly degrades beyond the 1-5, 6-10, and 11-15 day intervals.  The study below is only noting the increase in Greenland blocking. We have seen similar record blocks near Alaska over the same period. Plus other regions have seen record blocking. Also notice the range of increasing highs and lows of the NAO with more amplitude to the index. 

https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/joc.4673

Greenland Blocking Index 1851–2015: a regional climate change signal

 

We present an extended monthly and seasonal Greenland Blocking Index (GBI) from January 1851 to December 2015, which more than doubles the length of the existing published GBI series. We achieve this by homogenizing the Twentieth Century Reanalysis version 2c-based GBI and splicing it with the NCEP/NCAR Reanalysis-based GBI. 

 

More recently, since 1981 there are significant GBI increases in all seasons and annually, with the strongest monthly increases in July and August. A recent clustering of high GBI values is evident in summer, when 7 of the top 11 values in the last 165 years – including the two latest years 2014 and 2015 – occurred since 2007. Also, 2010 is the highest GBI year in the annual, spring, winter and December series but 2011 is the record low GBI value in the spring and April series. Moreover, since 1851 there have been significant increases in GBI variability in May and especially December. December has also shown a significant clustering of extreme high and low GBI values since 2001, mirroring a similar, recently identified phenomenon in the December North Atlantic Oscillation index, suggesting a related driving mechanism. We discuss changes in hemispheric circulation that are associated with high compared with low GBI conditions. Our GBI time series should be useful for climatologists and other scientists interested in aspects and impacts of Arctic variability and change.


52E192FA-4064-47B4-9A04-763EC6110D9C.thumb.jpeg.489171f4ba3218ee69a031e837b192f4.jpeg

 

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1 minute ago, bluewave said:

They can’t since model skill quickly degrades beyond the 1-5, 6-10, and 11-15 day intervals.  The study below is only noting the increase in Greenland blocking. We have seen similar record blocks near Alaska over the same period. Plus other regions have seen record blocking. Also notice the range of increasing highs and lows of the NAO with more amplitude to the index. 

https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/joc.4673

Greenland Blocking Index 1851–2015: a regional climate change signal

 

We present an extended monthly and seasonal Greenland Blocking Index (GBI) from January 1851 to December 2015, which more than doubles the length of the existing published GBI series. We achieve this by homogenizing the Twentieth Century Reanalysis version 2c-based GBI and splicing it with the NCEP/NCAR Reanalysis-based GBI. 

 

More recently, since 1981 there are significant GBI increases in all seasons and annually, with the strongest monthly increases in July and August. A recent clustering of high GBI values is evident in summer, when 7 of the top 11 values in the last 165 years – including the two latest years 2014 and 2015 – occurred since 2007. Also, 2010 is the highest GBI year in the annual, spring, winter and December series but 2011 is the record low GBI value in the spring and April series. Moreover, since 1851 there have been significant increases in GBI variability in May and especially December. December has also shown a significant clustering of extreme high and low GBI values since 2001, mirroring a similar, recently identified phenomenon in the December North Atlantic Oscillation index, suggesting a related driving mechanism. We discuss changes in hemispheric circulation that are associated with high compared with low GBI conditions. Our GBI time series should be useful for climatologists and other scientists interested in aspects and impacts of Arctic variability and change.


52E192FA-4064-47B4-9A04-763EC6110D9C.thumb.jpeg.489171f4ba3218ee69a031e837b192f4.jpeg

 

What's that huge double peak at the end?  2009-10 and 2010-11?

 

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51 minutes ago, LibertyBell said:

and the last time that happened was back in the 1780s during that famous New England winter? wow...if I remember correctly that was the winter with the snowstorms that buried entire houses.  NYC and Philly may had over 100" of snow

You are thinking of 1779-1780 when Philly may have had one day above freezing in January which hasn’t happened since then.

 

C037A831-AD00-4863-81D8-C94CA5831A63.jpeg.603e58a0a5e2844aa8884b603b2110f5.jpeg

B4C6ABAD-10EA-409B-9910-FF00DE5B6839.thumb.jpeg.c35b8ac9d409bcf65089b02625db2f04.jpeg

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2 minutes ago, EastonSN+ said:

Both EPS and GEFS have great looks for us.

Hard not to be intrigued when both are showing same progression.

The blocking is happening. That's not really too much in doubt anymore I think. Part of that process has already started. I understand the caution of some though too. There's a lot of moving parts. 

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