Glacier annual balance measurement, forecasting and climate correlations, North Cascades, Washington 1984–2006

Abstract. North Cascade glacier annual balance measured on 10 glaciers from 1984–2006 yielded mean annual balance (b_a) of −0.54 m/a, and −12.38 m cumulatively. This is a significant loss for glaciers that average 30–60 m in thickness, 20–40% of their entire volume. Two observed glaciers, Lewis Glacier and Spider Glacier, no longer exist.

The b_a of North Cascade glaciers is reliably calculated, correlation coefficient 0.91, using 1 April snowpack water equivalent and ablation season temperature. Utilizing b_a from 10 glaciers 1984–2006 and net balance (b_n) from South Cascade 1960–2005, a set of forecast rules for glacier mass balance were derived utilizing October–April Pacific Decadal Oscillation and Multivariate El Nino Southern Oscillation index values. The forecast rules provide a correct assessment in 41 of the 46 years for South Cascade Glacier and 20 of 23 years for NCGCP glaciers. Glacier annual balance forecasting is an important step for summer water resource management in glacier runoff dominated stream systems. The forecast for North Cascade glaciers in 2007 is for a negative b_a.