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After a cooler than normal summer and a very inactive Atlantic hurricane season what can we expect for the upcoming winter across the Washington Region?  The latest climate models continue to suggest there is a 60 to 70% probability of a weak El Nino developing late this fall and continuing through the upcoming winter. 

After researching historical analog years (historical climate data with similar conditions, etc.) I found eight weak El Nino winters and further drilled down to six years that had similar summer conditions (temperatures, inactive Atlantic hurricane season, active Pacific hurricane season and a developing weak El Nino). 

Tim’s Washington DC Metropolitan Area 2014 – 2015 Snowfall Forecast (Click on image for larger view)

Keep in mind that before you go and buy a snow blower these snowfall predictions are based on an average of the seasonal snowfall that fell during those six analog years. Some analog years featured below average snowfall and others well above average snowfall. The reason for wide variations in the six analogs has to do with the unpredictable nature of the North Atlantic Oscillation. If the NAO (North Atlantic Oscillation) does indeed remain mostly negative (increased blocking over eastern Canada & Greenland) during the upcoming winter, I would be surprised if the Washington Region didn’t receive at least one Nor’easter with heavy snowfall.

Tim’s Washington DC Region 2014 – 2015 Snowfall Forecast (Click on image for larger view)

Northeast Winter Forecast (Washington, Baltimore, Philadelphia, New York & Boston) 2014 – 2015:

DCstorms.com Northeast Winter Forecast 2014 – 2015 (click on image for larger view)

Analog Years (The historical climate data used to produce this snowfall forecast):

I averaged the snowfall that occurred during the 6 analog years and here is what the big cities received.

Temperature anomalies associated with the 6 analog years that I chose (image courtesy: NOAA).  I expect colder than average temperatures across a large portion of the eastern United States.

Precipitation anomalies associated with the 6 analog years that I chose (image courtesy: NOAA). I expect near normal to above normal precipitation across the Gulf coast and up the eastern seaboard.

Upper Level (500 mb) Height (High & Low Pressure) Anomalies during the six analog years I chose:

A look at the 500 mb (upper level) height anomalies during these years suggests a ridge across the Pacific northwest, a deep trough in the east and massive blocking over Greenland.

Average Snowfall across the Washington DC Region:

Average Snowfall in the Washington Metropolitan Area: