The Influence of Terrain on Snowfall During Strong Southerly Flow in the Snake River Plain A Case Study: 1 January 2004

The complex topography of southeast Idaho creates significant forecast challenges as it interacts with various synoptic and mesoscale flow regimes. Strong winter storms can produce consistent snow amounts over a substantial portion of southeast Idaho; however, winter storms which generate strong southerly flow can produce geographically disparate snow amounts.

This case study examines a winter storm on 1 January 2004 in which strong southerly winds of 20-30 ms-1occured for several hours. This regime generated downslope flow which delayed the onset of snow in the southern area of the Lower Snake River Plain (LSRP). In addition, the northern portion of the LSRP received persistent heavy snowfall during the same period due to strong upslope flow.