- Last time the NAO Index was neutral was back in late October when parts of the DC Area received one to four inches of snow.
- Since the late October snow storm the NAO index has been positive.
- Forecast ensemble models (see graph below depicting red lines) predict the NAO index may go neutral or negative towards the end of January.
- In order to get a major east coast snow storm, you must have blocking over Greenland (a massive area of High Pressure) found during a negative NAO oscillation.
Ski resorts are suffering in the Mid-Atlantic and New England (Northeastern United States):
Temperature Anomalies During a Positive NAO Index:
** Other factors contributing to the extremely mild start to winter has been the Arctic Oscillation (AO) index which has also been positive favoring strong westerlies over the high latitudes. The lack of an amplified jet stream (lack of high latitude blocking/strong westerlies) has kept all the arctic air locked up in Alaska, extreme northern Canada and Greenland.
** Notice that the AO is beginning to drop drastically over the next several days indicative of the arctic blast heading to the Midwest, Mid-Atlantic and New England Monday through Wednesday (the end of the black line in the chart below shows the current AO index; the red line depicts where the multiple forecast models are predicting the index to be in the future).