Wednesday, December 24, 2014

Let's run the numbers...

Adding to my post yesterday, I'm going to look further into the QBO signal and try to confirm or dismiss any rumor that "winter is over".

Here are the winters with a similar QBO Phase:

Here is how much snow fell in NYC those winters. We need to figure out what year matches up best with this year and what in the world happened in 2005-2006.

So right away I took a look at the ENSO phase. (Basically was it an El Nino, La Nina, El Nada?) Interestingly enough there is no consistency with ENSO phase and -QBO as seen below, but there is one year that's pretty similar. This year (so far) and 1979-1980 both feature a weak El Nino. The very snowy season of 2005-2006 was a neutral phase while the rest were La Nina.

Then I decided to look at the PDO, NAO, AO, AMO, and EPO which all gave me charts looking like the one below. Basically there is no link between these years and those indices. This could mean something else over powered the other indices or basically these winters only have the -QBO in similarity and it doesn't mean much for the winter pattern. Let's keep digging.

I finally looked at the PNA and saw that the trend was there, but nothing to impressive. How ever I had a difficult time finding this years line on the chart.

It was nearly over lapped by 1979-1980. That winter is linking up again with this one. This makes 79-80 a strong candidate for a matching analog winter.  

During most these years the PNA started off positive and went negative at times during the mid to late winter when I also noted NYC saw it's snowiest months, which is not expected. The data is conflicting and points to another force at play here. 

What ever happened in 2005-2006 is not happening this year (so far) in the data. As I could find nothing to match it up with. The 79-80 winter however linked up a little better but still has much that isn't in common with the numbers this year so far. The other 70's winters, had no signs of any linkage. The strong -QBO events of this past decade have way more in common when we start looking at long trend terms and patterns. 

My conclusion, the strong -QBO has minor influence on our winters and is only a percentages of the larger picture in a winter forecast. It alone cannot be used to determine how winter will behave. I made this decision after seeing very little in the way of linkage between this winter and the other winters with similar QBO indices. A strong -QBO can produce both snowy/snow less winters as seen in the data. I would love to use the majority of the 1970's winters as evidence but there are a few multi-decadal oscillations that are in totally opposite regimes today than 30+ years ago. Going off the data from this last decade it looks like we still have a strong possibility for a snowy winter though not at cold as last, which is still in line with my winter forecast. 

 I would love to hear some feedback from this. Any opinions and ideas are welcome. Thanks for reading!

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