Winter cyclone frequencies over the eastern United States and adjacent western Atlantic, 1964-1973.

Abstract

Analyses of winter cyclone frequency and deepening rates are presented for a 10-year period over the eastern United States and western Atlantic Ocean. Results are presented for 1SUP latitude-longitude quadrangles. The data source was microfilmed copies of NOAA's North American Surface Charts series routinely available over facsimile every 3 h. The analyses reveal a concentration of storms in a band from Cape Hatteras to New England, over the northern edge of the Gulf Stream current, and over the eastern Great Lakes. In addition, distinct minimums of winter cyclones are evident over the Appalachian Mountian range and, to a lesser degree, over the Florida pensinsula. Analysis on a similar scale of 3 h pressure changes in these cyclones indicates that deepening was most favourable over the southern Appalachians, immediate Carolina coastal strip, the northern edge of the Gulf Stream, and the eastern Great Lakes. Sigificant positive or negative departures from normal winter precipitation along the East Coast of the United States may be attributed to anomalies in adjacent sea surface temperatures, as evidenced by investigation into precipitation data and offshore sea surface temperatures of three regions exhibiting such departures. (A)