Climate Trivia: East Coast Winter Storm Frequency and ENSO
December is East Coast Winter Storm (ECWS) season. These storms are powered by warm water that flows from the Gulf Stream. The Gulf Stream current flows along the Eastern Seaboard past Florida and the Carolinas before reaching Cape Hatteras, where the warm water heads out into the Atlantic. ECWS’s travel northward along the coast causing high winds and coastal property damage comparable to hurricanes. They also bring heavy snowfall, causing further weather complications. On average, there are 12 ECWS’s during the December to February season, with January being the most active month. One of the best predictors of how intense an ECWS season will be is the ocean temperature along the coast of the southeastern U.S. during the previous summer (Gulf of Mexico temperatures were above average this past summer). The warmer these waters are, the stronger the Gulf Stream generally is and the more active the winter storm season will be. Interestingly, conditions in the eastern tropical Pacific affect ECWS activity as well. What eastern tropical Pacific conditions are most conducive to an active ECWS season?
a) El Niño conditions (warmer eastern tropical Pacific SSTs)
b) La Niña conditions (cooler eastern tropical Pacific SSTs)
c) Neutral Conditions (average eastern tropical Pacific SSTs)
The correct answer is a. More active ECWS seasons tend to coincide with El Niño years. This is in contrast to Atlantic hurricane season trends, as El Niño conditions tend to suppress Atlantic Hurricane formation. Over the second half of the 20th century, the frequency of ECWS events showed little trend, but the storms did become slightly more intense.
Season: Winter
Sources: DeGaetana, AT et al. “Statistical Prediction of Seasonal East Coast Winter Storm Frequency.” Journal of Climate 15 (2002): 1101-1117 and Hirsch, ME et al. “An East Coast Winter Storm Climatology.” Journal of Climate 14 (2001): 882-899 and Eichler, T and Higgins W. “Climatology and ENSO-Related Variability of North American Extratropical Cyclone Activity.” Journal of Climate 19 (2006): 2076-2093 and National Oceanic and Atmospheric Administration: Climate Prediction Center. Accessed Online 7 December 2009 http://www.cpc.ncep.noaa.gov/products/precip/CWlink/stormtracks/eisdiffobs.meta.gif
