Hydrologic Outlook: A Low Threat Of Spring Flooding
The potential for flooding due to spring snowmelt in the California-Nevada River Forecast Center`s (CNRFC) domain is below normal due to below normal snowpack and drought conditions predominating across California and Nevada.
Flooding in California remains a slight possibility due to the seasonal threat of heavy rainfall alone, or combined with snowmelt any time during the spring.
Everywhere from the Klamath Basin at the Northern part of the region to the Tulare Basin in the Southern Sierra Nevada is experiencing below average snowpack.
For the Sierra Nevada, regional snowpack levels range from around 45%, 60%, and 70% of average for the water year to date for the Southern, Northern, and Central Sierra Nevada, respectively.
Precipitation totals across the region for the water year to date range from about 35-65% of average. Many regions in California have observed five consecutive months of below average precipitation.
Last year at this time precipitation totals for California were around 50% of average.
The seasonal runoff forecasts closely follow the snowpack conditions. At this time, below normal runoff volumes can generally be expected during the April-July period for CNRFC`s snowmelt-dominated and non-snowmelt-dominated basins.
Flooding potential during the spring snowmelt seasons is below normal due to the below normal snowpack. The potential for large springtime rainfall events resulting in river flooding is still present and should be monitored throughout the Spring.
In Summary: The risk of California flooding during the snowmelt season is below normal this year for the Southern Cascades through the Sierra Nevada. Nevertheless the possibility for flooding remains due to the possibility of heavy rainfall or the combination of rain and snowmelt at any time during the Spring.