US East Coast Winter Storms: Are They Becoming More Extreme?
Bernhardt, J.E. and DeGaetano, A.T. 2012. Meteorological factors affecting the speed of movement and related impacts of extratropical cyclones along the U.S. east coast. Natural Hazards 61: 1463-1472.
In an earlier study, as Bernhardt and DeGaetano describe it, "Hirsch et al. (2001) defined an ECWS as an area of low pressure with a closed circulation, moving in a general south-southwest to north-northeast direction and containing winds greater than 10.3 m/sec during at least one 6-hour period," which wind criterion was selected because "it represented a threshold for wave damage given by Thurman (1983)." In addition, they state that the system had to be located along the East Coast, in a box bounded at 30°N by 75 and 85°W and at 45°N by 65 and 70°W. And based on this definition, Bernhardt and DeGaetano calculated the speeds of all ECWS over the 55-year period 1951-2006. And what did their calculations show?
The two US researchers report that "the speed of ECWS during their passage over or near the east coast of the United states varied substantially from storm to storm, month to month, and season to season." However, as can be seen from the figure below, over the entire time period of their study, Bernhardt and DeGaetano rightly declare "there was no clear trend in ECWS speed."
Average seasonal nor'easter storm speed. Adapted from Bernhardt and DeGaetano (2012).
Against all odds, as one could rightly claim in this particular instance, the global warming that occurred between 1951 and 2006 did not lead to an increasing trend in the extremeness of East Coast Winter Storms.
Davis, R., Dolan, R. and Demme, G. 1993. Synoptic climatology of Atlantic coast northeasters. International Journal of Climatology 13: 171-189.
Frankoski, N. and DeGaetano, A. 2011. An East Coast winter storm precipitation climatology. International Journal of Climatology 31: 802-814.
Hirsch, M., DeGaetano, A.T. and Colucci, S.J. 2001. An east coast winter storm climatology. Journal of Climate 14: 882-899.
Thurman, H.V. 1983. Essentials of Oceanography. Merrill, Columbus, Ohio, USA.