Snow and ice accumulation does not impact river conditions right away, but is instead stored at the soil's surface. During warmer periods, snow cover melts, which may cause river rises similar to that caused by rainfall. Snow cover is modeled to help improve river forecasts.
National Winter Weather Forecasts
Forecasts for snow and ice precipitation from the Weather Prediction Center
National Snow Analyses
Official snow cover analyses and forecasts for the U.S. from the National Operational Hydrologic Remote Sensing Center
Snow and Ice Climatology
Snow and ice information for the U.S. and the globe