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Mid-December Update

By Joe D'Aleo
Monday, December 21, 2009


El Nino continues towards it peak (this month or next) as the Kelvin wave triggered by good wind westerly bursts last few months comes east, lowering the thermocline and causing sea level rises (like sloshing water in your bathtub).


It should peak in upcoming few weeks and then begin to subside. All dynamical and statistical models available as of mid November suggest this.




The median forecast puts it on the upper end of the middle range of moderate El Ninos at least in terms of NINO region 34 temperatures. Eastern areas are less warm.

The analog years for such a median El NINO suggest a cold southeast, as is the official NWS CPC forecast.


 




THE QBO




Research by Barnston, Livesey and Halpert at the CPC and then others suggested ENSO (both El Nino and La Nino) is modulated by the QBO, a quasi-biennial oscillation of the winds high up over the tropical Pacific which goes through alternating phases of west and
east anomalies. Ming Cai at the University of Maryland found a tendency for enhanced potential vorticity in east QBO years in lower mid-latitudes and colder temperatures across much of the US in DJF along with northeast Canada blocking. Westerly QBOs tend to produce more of a positive PNA pattern with a western North America ridge and eastern trough. It is cold in east QBOS in Siberia and warmer in west QBOs.




Westerly QBO winters also tend to display a PNA pattern while easterly QBO more of a negative. Easterly QBOs tend to be warmer in the east in conflict with a composite of all ENSO cases.




Given the PNA pattern, westerly QBOs tend to have more east coast snowstorms, east QBO El Ninos much less.









This kind of road picture is less likely in east QBO El Ninos.




However, the QBO at the key level in the research, 45mb is still transitioning from westerly this month. I had speculated that this winter the best chance for a blockbuster could be early (December). The storm this weekend looks like a major event with another just after Christmas. 

 


EL NINOS BIASED CENTRAL TROPICAL PACIFIC


This El Nino and some earlier this decade, had a tendency to have their warmth focused more in the central Pacific than in the east.





This has an effect on the pattern:






The 500mb pattern with central Pacific focused El Ninos suggest colder east across the western Europe.



THEN WE HAVE A QUIET SUN

 

The super long and quiet solar minimum continues, 3 years after NASSA first indicated solar min had arrived.




The number of sunspotless days continues to mount with 2009 ranked now in 5th place for all years since 1849, right behind 2008. Just a half dozen more this month will move us ahead of last year. We are approaching 800 spotless days total this minimum three times the number on most recent cycles.





A NEGATIVE PDO AND A COOLING ATLANTIC

 

After a bit of bounce this fall, PDO has declined negative again, indicating that the new regime persists. The negative PDO is responsible for the La Nina like storm track this fall with heavy snows in some of the same areas hard hit in the last two La Nina winters.




It also suggests that the El Nino will end quickly as it tends to do in cold PDO decades, perhaps faster than the models all show.





Note the similarity of the ocean and solar with the 1960s. It may be as we have shown in early posts similar to the late 1700s and early 1800s Dalton Minimum although we don’t have data then to correlate to.





East QBO
low solar winters, tend to look a lot like El Ninos with tropical warmth in the central Pacific (in fact even colder).





NEGATIVE AO/NAO

As we posted a few weeks back, some stratospheric/high atmospheric warming in the polar regions would lead to a collapse of the AO/NAO. Indeed it has continued.



This is why the cold air is dumping to mid-latitudes. This kind of stratospheric warming/ blocking is favored in east QBO low solar minima as Labitzke (2002) showed here.

 

The warmings build arctic high pressure beneath and force the polar front south. Note the negative correlation with solar flux in east years and positive in west QBO winters.


The means this warming is favored in low solar east and high solar flux west years.





From Sunspots, the QBO, and the Stratosphere in the North Polar Region 20 Years later

Karin Labitzke, 2005

 

A negative NAO correlates with cold east and east coast snows.





The AO and NAO is off the charts and would favor the snow this month at least.   

 

LAST MINUTE UPDATE

The blockbuster storm of December 18-20th brought daily and December snowfall records in Baltimore, Washington and many surrounding towns. Philadelphia had a top ten snowstorm and a two day record. New York CIty had a 10 inch snow and over 20 inches of snow fell on parts of Long Island.

  
The storm moved east and though heavy snow fell in southeastern New England, most areas to the north had less or nothing. Next week, we will do a detailed summary of this memorable storm.

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