1. Modeled Snowmelt contributed between 0-23% of the total basin input during the top-10 extreme storms Dependent on Basin area shape, Forest cover, and the timing of the storm’s rain-snow transition. How Important is Snow During Rain-on-snow Floods over the Western U.S. Mountains? Nic Wayand, University of Washington

2. 1-year in the life of snow in the rain-snow transition zone Snoqualmie Pass, Central Washington Cascades, USA.

3. “Typical” Storm SNOWFALL RAINFALL RUNOFF No runoff production Elevation Z 1 AREA contributing overland runoff to stream Photo credit: Flickr.com User: Lucas – K Lu Slide by Mark Raleigh RUNOFF

4. Rain-on-Snow Event SNOWFALL RUNOFF Elevation Z 2 Rain-on-Snow event produces Larger AREA contributing overland runoff to stream Warmer Storm (1 week later) Elevation Z 1 ΔZΔZΔZΔZ RAINFALL Photo credit: Flickr.com User: Lucas – K Lu Slide by Mark Raleigh Snowcover exposed to warm, windy weather

5. Snow Depth Elevation More Snow at Higher Elevations Potential melt Snow depth Maximizing Snowmelt More Energy for melt at Lower Elevations Sweet Spot for Melting Snow Warmer Temperatures Melt Energy

6. Using a Simplified basin model Rain-snow elevationBasin ShapeBasin Forest Cover Area of Melting Snow Low Rain-snow transition High Rain-snow transition Area of Melting Snow Photo credit: Flickr.com User: Lucas – K Lu Top: http://cascadeclimbers.com/ User: off_the_hook Bottom: http://thesnowtroopers.com/ User: Sting http://thesnowtroopers.com/ User: Sting Uniform Area Basin “Fat” Area Basin Lots of Forest Clearings Elevation Snowfall Rainfall Snowfall Rainfall Snowmelt Input (%) San Joaquin basin, CA Snoqualmie basin, WA E. North Fork Feather basin, CA Less snowmelt More snowmelt

7. High school Outreach: Rain-on-Snow Lesson Video snap shot goes here Link to material http://tinyurl.com/oqo8ml7 Outreach video http://youtu.be/CWeR7_yu6H8