Weather and Climate Data Analysis: Detecting Signals for High D.C. Snow Seasons

The goal was to compare global weather and climate data signals for years that Washington, D.C. experienced above average snowfall during meteorological winter months of December, January, and February. The years chosen were pulled from the following link that documents all D.C. seasonal snowfall from the D.C. area National Weather Service office. All maps were produced from NOAA/ESRL Physical Science Division, Boulder Colorado form their website at http://www.esrl.noaa.gov/psd/.

U.S. Winter Air Temperature Tendencies (NOAA/ESRL Physical Science Division)

The first map shows lower than average temperature anomalies for the D.C. area from December to February during years that D.C. experienced high snowfall years of at least 20".  The average seasonal snowfall in D.C. is 15".  These regional lower temperatures should be expected as a result of vast snow-cover reflecting solar radiation that would otherwise be absorbed by the Earth's surface as heat without the snow-cover.  Another interesting result is how most of the continental U.S. also tends to experience low temperature anomalies during D.C. high snowfall years.

 U.S. Winter Precipitation Rate Tendencies (NOAA/ESRL Physical Science Division)

U.S.Winter Soil Moisture Tendencies (NOAA/ESRL Physical Science Division)

The next two maps show that high D.C. snow years tend produce above average precipitation rates (top) and slightly above average soil moisture (bottom).  High precipitation rates also typically result in high concentrations in soil moisture.  Similar correlation over the Ohio Valley has interesting results that low precipitation rates tend to lead to low soil moisture during years that D.C. has high snowfall.

Northern Hemisphere Winter Sea Level Pressure Tendencies (NOAA/ESRL Physical Science Division)

 
Global teleconnection signals can also occasionally be linked to repetitive weather events and associated climatic trends.  The next map (above) shows the tendency for a negative North Atlantic Oscillation (NAO) during D.C. snow years with higher than normal sea level pressure tendencies over the arctic region.  This result verifies the many scientific studies that a negative North Atlantic Oscillation (NAO) correlates well with Eastern U.S. low winter temperature anomalies.  

 

Winter Tropical Pacific Sea Surface Temperature Tendencies (NOAA/ESRL Physical Science Division)

The final map generated shows a strong El Niño signal during high D.C. snow years.  Not only does the map generate an El Niño signal, but also a Modoki El Niño signal where the warm sea surface temperature anomalies are centered over the central Pacific basin rather than the typical East Pacific El Niño. 

The NOAA/ESRL Physical Science Division products are excellent tools for generating atmospheric signals that can be verified with past, present, or future conditions.  This analysis for D.C. high snow years can be reproduced for other locations and weather events over various time periods of interest.