Not your father’s La Nina Winter
This winter has really been quite amazing. I’m not a long range forecaster, but at first glance it seemed like this winter’s forecast would be pretty straightforward. Why?
Well, beginning last summer a La Nina started to develop in the Pacific. Now this has turned out to be a very strong La Nina. That’s great news. Usually the stronger a signal the easier the forecast. Makes sense.
If we look at past strong La Nina winters we usually see dry and warm weather in Florida with the threat of occasional very short cold snaps (sometimes a short severe snap can happen).
In fact, most of the Eastern United States is warm.
Well, one thing that was not seen is the persistent and strong negative Arctic Oscillation. This refers to the pressures in the high latitudes toward the pole. A negative phase means there are higher than normal pressures there which in turn forces cold air south and can mean a more active storm pattern.
Put those two together and you get a cold Midwest and East with more snow than rain.
Will the Arctic Oscillation (AO) turn positive? It’s trying to head there now but for how long?