What Does NOAA’s Winter Outlook Look Like?

NOAA recently issued their seasonal forecast for the upcoming winter.  Unlike last winter’s El Nino, NOAA is expecting La Nina to influence this winter’s weather across the United States.  It is not, however, expected to be as significant as last winter’s El Nino event (the strongest El Nino since 1997-98).  La Nina is characterized by below average water temperatures in the east central Equatorial Pacific Ocean.  

La Nina conditions typically contribute to drier and warmer than average winters in the southern United States while parts of the northern United States experience wetter and cooler than average conditions.  Consequently, NOAA anticipates a greater than 50% chance of drier than average conditions this winter from Texas to Florida.  NOAA also says there is a greater than 40% chance of wetter than average conditions this winter in parts the northern Rockies and in the Great Lakes Region.

According to NOAA’s winter weather outlook, there is a greater than 50% chance of above average seasonal temperatures from Arizona to Texas.  That’s in addition to a greater than 40% chance for below average temperatures along parts of the U.S.-Canadian border this winter.  The Mid-Atlantic Region is in between these temperatures and precipitation projections with an “equal chance” for above and below average winter temperatures and precipitation.

It’s easy to see the variability from one winter to the next in the Nation’s Capital during just the last ten years.  During last winter’s El Nino event, Washingtonians experienced a warmer than average season with an average temperature of 42.0 degrees Fahrenheit (combining daily high and low temperatures) from December through February.  However, Washingtonians remember last winter not for the milder than average temperatures but for the 4th largest snowstorm on record when 17.8” of snow occurred in the Nation’s Capital on January 22-23.  That’s in contrast to the 1997-1998 El Nino winter when only 0.1” of snow fell in Washington, D.C.

The 2009-2010 winter was the snowiest on record in the Nation’s Capital when 56.1” of snow fell and that occurred during a moderate episode of El Nino.  By comparison, the warm (43.4 degrees average temperature) and relatively snow-free (2.0”) winter of 2011-2012 occurred during a moderate episode of La Nina.  An average winter in Washington, D.C. features an average temperature of 38.2 degrees and 15.4” of snow.  

Some important things to remember are that storm track is vital whether or not an episode of El Nino or La Nina exists.  In addition, there are many factors involved in issuing winter weather outlooks.  The phase of the “Oceanic Nino Index” which shows the presence of either El Nino or La Nina, along with the Arctic Oscillation and the Madden-Julian Oscillation are all important factors to consider.  

With so many factors involved in seasonal forecasts and an inherent amount of uncertainty in storm track, it’s vital to pay attention to the latest weather forecasts for your community.  That’s especially true in the DC Metro Region where a difference of a just a few miles can make a world of difference.  For example, while National Airport saw 17.8” of snow during January’s record storm, Dulles Airport saw 29.3”.  My colleagues and I on the WUSA9 weather team will continue to provide you with the latest weather updates.