An East Coast winter storm climatology

Abstract

A climatology of East Coast winter storms (ECWS) was developed using an automated procedure. This routine was used along with the NCEP-NCAR reanalysis dataset (1948, 1951-97) to identify storms over the October-April winter season. An array of statistical analyses was used to empirically analyze the interannual variability of these cyclones. To be classified as an ECWS, an area of low pressure was required to have a closed circulation, be located along the east coast of the United States (within the quadrilateral bounded at 45°N by 65° and 70°W and at 30°N by 75° and 85°W), show general movement from the south-southwest to the north-northeast, and contain winds greater than 10.3 m s-1 (20 kt) for at least one time period (6 h). Storms meeting the above criteria were also required to have a closed circulation and be located within the quadrilateral during one additional 6-h period (not necessarily consecutive with the first). On average, 12 ECWS occurred per season with a maximum in January. Significant trends in storm frequency over the 46-yr period beginning in 1951 are not evident. However, a marginally significant (α = 0.10) increase in average storm minimum pressure is noted. Spectral analysis of the ECWS time series shows significant cycles with periods of 2.3, 2.8, 3.4, 4.8, and 10.2 yr, which are in agreement with documented periodicities in joint Atlantic SST and sea level pressure data. Average monthly ECWS frequency anomalies are significantly higher during El Niño months when compared to neutral months over the October-April storm season. ECWS show little or no change in frequency anomalies during La Niña months.