Thursday, October 13, 2011

Is the Atlantic the Key to a Cold January?

Over the years, we have learned to use analogues from previous winter in formulating our winter weather forecast. Recently, most of this data was made accessible on the internet for anyone to play with. Want to compare El Nino with temperatures in February for instance? Its right there. How about the arctic cold in December with January snowfall? Not to worry. its readily available to any backyard weather fan to analyze. Without going into great detail, the indices we are looking at for this winter parallel several winters in the past especially the early 1950s--not completely but pretty close.

One of the factors that doesn't completely match up is the Atlantic tropical sea surface temperatures. Many meteorologists.climatologists believe the role the Atlantic Ocean plays in our winter temperatures can be significant. Why would we pay any attention to this when its obviously so far away from North America? The same question we could ask about El Nino since it occurs in the middle of the Pacific Ocean. Yet we know that changes in the Pacific Ocean play a direct role in the weather across the US.

First, look at the sea surface temps from January of 1950 and 1951. Notice the colder than normal water in the middle of the Atlantic
Although this isn't the only factor that had an effect on temperatures in these years, look at the warmer than normal temps across the eastern US
The high off of the coast in both years was fairly strong although stronger in 1950 than in 1951. A reflection of this weaker high is evident in the snowfall in Cleveland in January: 3.7" in 1950, 17.5" in 1951
Compare those Januarys to the last January (2009) that best fit the early 1950s: January 2009. Notice how much warmer the sea surface temperatures were.
The resulting temperatures were well below normal
The high was well off of the coast and the cold, trough was smack, dab in the middle of the Great Lakes and eastern US. The resulting snow for Cleveland was mindblowing: 40.5", second most only behind January of 1978
How about this January? Look at the Atlantic sea surface temperatures going into October. They are not as cold as 1950 or 1951 but there is some evidence of cooling in pockets. Whether or not this continues for the remainder in the fall is still uncertain.
Could this "Atlantic cooling"--if it continues--create a "not as brutal" January for northern Ohio and much of the east coast (all other factors being equal)? If you are a snowplow driver, stay tuned. More on this in mid-November when the new temperatures come out!