Atlantic Sea Surface Temperatures and New England Snowfall

Abstract

This paper examines the possibility of an association between winter (December-March) snowfall in New England and sea surface temperature anomalies (SSTAs) in the adjacent Atlantic Ocean. Regional snowfall indices for southern and northern New England were obtained by rotated principal components analysis (PCA). Composite maps of winter Atlantic SSTAs and 700-mb geopotential height anomalies were generated for cases of above and below average winter snowfall totals for southern and northern New England, respectively. A monthly index of SSTAs around the coast of New England was obtained from rotated PCA of SSTAs in the western Atlantic Ocean and compared for high snow and low snow cases.In northern New England, no direct association between snowfall and SSTAs is indicated by either the composite maps or the monthly SSTA index -high or low snowfall totals can be attributed primarily to anomalies in the 700-mb circulation. In southern New England, high (low) snowfall totals are associated with negative (positive) SSTAs off the Atlantic coast, and these anomalies are often already evident in December, suggesting Atlantic sea surface temperatures may be of utility in long-range winter forecasts for coastal regions.

U.S. East Coast Trough Indices at 500 hPa and New England Winter Climate Variability

“…On the other hand, our results confirm earlier work that found snowfall in southern coastal NE to be significantly associated with regional SSTs. As noted by Hartley (1996), the typical persistence of SSTs makes this association potentially useful for the purpose of winter climate forecasting.…”

“…Despite the important affects of snowfall on regional transportation and commerce (Hartley 1996), no good predictor for snowfall in the northern NE states has been found. This problem is made more difficult by the fact that snowfall is governed by a combination of highly variable parameters including storm tracking and regional temperature.…”

“…Both NE SSTs and the NAO are related to longitudinal shifting of the trough axis, such that cool regional SSTs and negative NAO index months frequently accompany an eastern trough axis position. Hence, given the established relationships between the NAO and both NE SSTs (Hartley 1996) and NE regional hydroclimate (Bradbury et al 2002) it is clear that the NAO has important, though complex, physical links with NE regional climate. Therefore, the synoptic conditions associated with the 1960s drought, which included persistent below-normal SSTs and an eastward-displaced trough (Namias 1966), were likely linked to the concurrent negative NAO conditions.…”

“…SST data were originally taken from NCEP-NCAR described in Smith et al (1996) and at the Web site: http:// dss.ucar.edu/datasets/ds277.0/. This study uses a subset of the monthly NCEP data as analyzed by season with rotated (varimax) principal component analyses (RPCA;Hartley 1996). Standardized monthly gridpoint values from January 1950 to November 1992 were averaged for several regions in the west Atlantic; each delineated according to loading patterns determined in the seasonal RPCA (available online at http://people.moreheadst.…”

Synoptic associations of winter climate and snowfall variability in New England, USA, 1950–1992

“…We have also to consider the possibility that the SSTAs are forced by the atmospheric circulation anomalies that result in the anomalous snowfall conditions, in which case the SSTAs do not directly affect snowfall and the association is merely coincidental. The time series of a seasonal SSTA index for the adjacent area of the Atlantic Ocean (Hartley, 1996) shows a remarkable resemblance to that of the NAO index (Figure 17). Cross-correlations are significant, with the NAO leading SSTAs by 1 and 2 years (Table II), although the levels of significance are probably inflated by strong persistence in the SSTA series (out to 3 years) and moderate persistence in the NAO series (1 year).…”