Two fast-moving clippers will slide across the Washington Area tonight and again on Saturday night. Snow showers and flurries are likely along with the potential for a dusting of snow. Why has this winter been so cold and snowless across the immediate D.C. Area so far?
The North Atlantic Oscillation (NAO) continues to remain in its positive phase and the end result remains a snow drought across the Mid-Atlantic states.
October 2013 through January 13, 2014 Upper Level Pattern:
- Massive ridge of high pressure (dark red colors) south and west of Alaska has caused the jet stream to drop south into the eastern United States resulting in numerous arctic outbreaks.
- Ridge of high pressure over the central Atlantic (yellow shading) has kept the storm track to our west, bringing the D.C. Area ice and rain as opposed to heavy snow.
- Dark purples and blues across the North Atlantic (eastern Canada, Greenland & Iceland) is indicative of the Positive NAO index or lack of blocking (high pressure aloft). A lack of blocking over the North Atlantic produces a fast southwest to northeast flow, causing storms that do form on the coast to move too quickly out to sea, preventing classic Nor’easters from crawling along the coast and dumping heavy snows on our region.
December 2009 through February 2010 Upper Level Pattern:
Our next blast of arctic air will arrive Tuesday night of the upcoming work week. Highs on Wednesday will struggle to get out of the lower 20s as the cold, snowless winter of 2013/2014 continues!