1. Meteorological Service of Canada, Environment Canada, 4905 Dufferin Street, Toronto, Ontario, Canada M3H 5T4, Institute for Ocean Sciences, Fisheries and Oceans Canada, Sidney, British Columbia, Canada V8L 4B2, and Wadsworth Center, New York State Department of Health, Empire State Plaza, P.O. Box 509, and Department of Environmental Toxicology and Health, State University of New York, Albany, New York 12202-0509