Advancements in iSnobal Modeling in WY2023

In the midst of a record-breaking snow year across many basins in California, M3 Works continues to push new model features in iSnobal.

Snowpack Forecasting

The series of significant atmospheric rivers in California in WY2023 put great pressure on reservoir operations in a number of California basins. As the snowpack continued to grow into February and March and the threat of rain-on-snow and melt events grew, water managers were eager for quantitative assessments of melt potential. M3 Works adapted our ability to drive iSnobal with gridded weather products to include using the GFS forecast, which now allows us to generate a 14-day snowpack forecast.

ASO Albedo Ingestion

One of the most powerful aspects of the physically-based model iSnobal is how it was designed, from the beginning, to be able to take advantage of remote sensing measurements in its architecture. We have ingested measured snow depths from ASO for over a decade. Now, for the first time, we are also ingesting ASO measured albedo. Albedo is the main control on snowpack melt in the spring, and the ability to include actual measurements of albedo gives significant improvement in model performance.

Modeled vs Measured albedo chart

Legacy iSnobal Bug Fixes

M3 Works discovered and addressed two bugs in the legacy code used to run iSnobal, and these fixes are now available in M3 Works modeling products. One bug was discovered in iSnobal itself, relating to the density algorithm. Although not broad in scope, the correction did improve WY2023 density performance compared to station and snow course measurements. The second bug was in input data variable distribution in the SMRF package. Although the distribution bug was also narrow in scope, it's correction resulted in tangible model improvements during certain storm events. Both fixes live in our Boreas modeling system.