Interannual variability of accumulated snow in the Columbia Basin, British Columbia

Snow water equivalent anomalies (SWEA) measured around April 1 by stations in the Columbia basin area in British Columbia, Canada, were studied for their interannual variability during the period 1950–1999, particularly in relation to El Nino/La Nina events and to high and low Pacific–North American (PNA) atmospheric circulation patterns. Composites of the SWEA showed that SWEA were negative during El Nino years, positive during La Nina years, negative during high PNA years, and positive during low PNA years. High PNA appeared to have the most impact on the SWEA, followed by La Nina, El Nino, and low PNA. In the Columbia basin area, La Nina effects (relative to El Nino effects) on SWEA decrease northward and eastward but strengthen with elevation. Composites of the Pacific sea surface temperature anomalies (SSTA) during the 10 lowest SWEA years revealed weak signals, with El Nino warm SSTA present only during spring and early summer in the preceding year and the SSTA pattern consistent with a high PNA present by fall and winter. In contrast, composites of the SSTA during the 10 highest SWEA years showed strong La Nina cool SSTA starting around May in the preceding year and lasting onto winter.