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

The ba of North Cascade glaciers is reliably calculated based on 1 April snowpack water equivalent and ablation season temperature. 1 May forecasting of ba using the Pacific Decadal Oscillation and the Multivariate El Nino Southern Oscillation circulation indices correctly determined the sign of mass balance in 42 of 47 years. 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 annual balance.