WINTER FORECAST 2011 -12 will it be the 3rd Active or Bad Winter in row?
FINAL FORECAST DEC 3
I wanted to wait until the end of the month and see the data for November 2011 before I issued any updated forecasts because the trends are important as you move into the heart of the winter months. Officially for example the NAO in 2011 was near record positive levels and this is also true for the AO.
Even though the snow cover has been extremely impressive for November across the northern hemisphere and especially over Eurasia the pattern is off to a vastly different start than what I anticipated... and for that matter what most other meteorologists had anticipated as well. It is clear that thee is not going to see any rapid change to a colder pattern across the western hemisphere and that most of the December 2011 forecasts are going to bust quite badly (mine Included).
There are several reasons for this but in my opinion and the primary reason was the early development of a very strong and intense polar vortex over Siberia and the Bering sea during the month of November. This is very strong negative anomaly corresponds or Teleconnects to a very strong positive anomaly over Greenland and Iceland aka the +NAO. In addition the GWO has consistently been stocked on the lower half of the GWO diagram... In the phases which only favor mild patterns over the eastern Conus and the stratospheric temperatures at 10mb have been extremely cold over the entire western hemisphere into Western Europe.
All that being said I need to point out that there has never been a persistent +NAO that has lasted all 3 months with a weak / Moderate La Nina and the QBO has been weak to Moderate Negative . Of course this could be a first but the data really does not support that and it does continue to indicate that the pattern is going to shift.
This first image shows us what the typical -PDO 500 MB pattern looks like. This image is strikingly familiar to the current pattern as we can see the persistent deep negative anomalies over Western Canada and the Pacific Northwest... the positive anomalies in the north central Pacific and also the occasional positive anomaly in the north central Atlantic.
This next image shows us what the typical weak to moderate La Nina Pattern looks like. We can see a very sick clear and strong positive anomaly over Greenland...a classic -NAO and below Normal Heights covering much of southwestern Canada into the northern Rockies the upper plains the Midwest into the northeast.
If we take a look at all the negative QBO winters since 1955 we get this pattern which is also equally impressive with the amount of blocking over Greenland and the large area of below Normal Heights over the eastern U.S. into the northwest and North Central Atlantic Ocean.
Another aspect to keep in mind is that for the last several months the QBO has been hovering close to neutral : since June the QBO has been between +4 and -4. Only in the last 30 days has it really begun to tank and it's the strong and negative values which is what helped causes the blocking pattern to develop.
And finally if we take a look at the top 8 AMO winters... again we see a strong indication of positive anomalies over Eastern Canada and Greenland.
Clearly my DEC 2001 forecast was AWFUL and disastrously wrong and I do not have to wait for DEC 30 to acknowledge it. The current pattern supports the cold surface HIGHs coming south into the Rockies and the Plains... the sliding off the East coast and staying there for several days.