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| Snow in Bethesda, MD (December 19, 2009) |
December can feature a wide variety of weather in the Nation’s Capital from mild and wet to cold and snowy. Although the last four December’s have been appreciably warmer than average, the last four winters were not warmer than average. However, this winter’s pattern could be different because one of the strongest El Nino’s on record has developed in the eastern Pacific Ocean.
NOAA’s monthly forecast calls for December to be
warmer and wetter than average in the Mid-Atlantic Region. That’s bad news for those longing for a white
Christmas. Although this part of the
country tends to see below average snowfall when there is a strong El Nino,
there have been exceptions. There was a
moderate El Nino event during the 2009-2010 winters – and that was the snowiest
winter on record in the Washington-Baltimore corridor.
December 2009 brought Washingtonians their 7th
largest snowstorm on record (16.4”) and was also the snowiest December on
record. According to the National
Weather Service, December 2009 was nearly two degrees colder (37.9 degrees)
than the monthly average temperature of 39.7 degrees. The 2009-2010 winter had a seasonal snowfall total
of 56.1” at National Airport (Washington, D.C. averages 15.4” each year).
However, the current El Nino is stronger than the
2009-2010 event. In addition, there are
other factors involved in issuing seasonal forecasts for the winter months in
the Mid-Atlantic Region and such as the phase of the North Atlantic Oscillation. The position of the jet stream can create all
the difference between significantly warmer than average and much colder than
average temperatures. For example,
December 2013 was 2.6 degrees warmer than average, while January 2014 was 3.8
degrees colder than average. A shift in
the position of the jet stream helped lead to a net swing of 6.4 degrees in the
Nation’s Capital in the span of a month.
Since El Nino is a seasonal event than spans a period
of several months, the prospect of a dramatic swing in monthly temperatures is
less likely this winter. However, a
shorter period of colder than average temperature is certainly possible at any
given point. Those rooting for a
significant winter storm should hope than an outbreak of cold air coincides
with a moisture-laden coastal storm – such as the December 2009 storm. My colleagues and I on the WUSA9 weather team
will keep you posted on the latest weather developments both on-air and
online.
Gee, I hope the current El Nino doesn't bring another monster storm to the D.C. area that it brought in 2009. So many residents lost power for days and had no choice except checking into hotels IF they were lucky enough to find a vacancy. Keep us posted, Chris!
ReplyDeleteYou have a good memory. That storm I took the photo in made December 2009 the snowiest on record. Early February 2010 was even snowier in what became the snowiest winter on record in many cities in the Eastern United States.
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