Meteorological Controls on Snowpack Formation and Dynamics in the Southern Canadian Rocky Mountains

Abstract

Considerable spatial variability in snow properties exists within apparently uniform slopes, often resulting from microscale weather patterns determined by local terrain. Since it is costly to establish abundant weather stations in a region, local lapse rates may offer an alternative for predicting snowpack characteristics. For two Castle Mountain Resort weather stations, we present the 2003–2004 winter season weather and snow profile data and the 1999–2004 winter season lapse rates. A third site was sampled for small-scale spatial variability. Layer thickness, stratigraphy, temperature gradients, crusts, wind drift layers, stability, and settlement were compared between the sites and correlated with temperature, wind, and lapse rates. Average yearly snowfall was 470 cm at the Base and 740 cm at the Upper station. Average daily maximum and minimum temperature lapse rates are −6.1°C km−1 and −5.7°C km−1 when inversions are removed. Inversions occur mostly at night, adversely affecting lapse rate averages. Lapse rate modes are unaffected and most often −6.3°C km−1. Snowpack spatial variability is ∼25% of layer thickness and is controlled by wind and topography. Layer settlement is primarily related to initial snow thickness and wind drift. Snowpacks stabilize with age, unless rain crusts are present, which are important low-force failure horizons.