["Centrally-based" El Nino during the winters of 2002-2003 and 2009-2010]
Winter is still a long ways away, but there are already some developments around the world that can give us a clue as to what kind of weather we can expect here in the Northeast U.S. during the upcoming winter of 2014-2015. One such development is now underway in the tropical Pacific Ocean as El Nino conditions (i.e., warmer-than-normal sea surface temperatures) are gradually forming just off the west coast of South America. There are two important factors with respect to an El Nino – magnitude and location - that can play significant roles in winter weather conditions here in the Northeast U.S.
[CFS model forecast for a "centrally-based" El Nino during the upcoming winter season]
A super strong El Nino would tend to lead to a warm winter in much of the U.S., but I do not expect that to happen despite some model forecasts to the contrary (for more on this: http://thesiweather.com/2014/04/22/1100-am-el-nino-on-the-way-but-odds-are-against-a-super-one/). Meanwhile, a weak-to-moderate El Nino in the tropical Pacific Ocean has been associated with cold and snowy conditions in the Northeast U.S., but it tends to depend on the given location of the particular El Nino. Specifically, weak-to-moderate El Nino’s that are “centrally-based” in the central Pacific Ocean as compared with the warmest sea surface temperatures relative-to-normal being right near the west coast of South America (i.e., “eastern-based") have historically led to snowy winters in the Northeast U.S. For instance, the winters of 2002-2003 and 2009-2010 featured “centrally-based” El Nino conditions and both winters were very snowy in the Northeast U.S. Indeed, there are some longer-range computer forecast models suggesting that this El Nino ultimately becomes “centrally-based” in the Pacific Ocean by the fall and continuing into the winter season. In fact, the similarities between the forecasted sea surface temperature anomalies for the upcoming winter (middle map) and the actual anomalies during the snowy winters of 2002-2003 and 2009-2010 (top map) are rather amazing. Not only are they both featuring "centrally-based" El Ninos in the Pacific Ocean, but both have a noticeable warm sea surface temperature anomaly tucked in near the Alaska coastline and a colder-than-normal region just to its southwest.
We’ll continue to monitor both the magnitude and location of the unfolding El Nino in the Pacific Ocean over the next few months here at thesiweather.com. Currently, it can be said that there are signs that point to a “centrally-based”, weak-to-moderate strength El Nino which could very well result in another snow-filled winter around here.