Late Winter Storms Boost Western Snowpack
California is still playing catch up, but several recent winter storms have added a cherry on top of the solid snowpack in the Western United States. Snowpack plays a number of important roles after the winter months, including provided water for drinking, agriculture, fire suppression, and recreation.
A multi-day rain and snow event pummeled California’s Sierra Nevada, with several feet of accumulation piling up over the first weekend in April. The wet storm then remained nearly stationary over the southern half of the state, where it continued to deliver heavy rain and high elevation snow through the following Friday.
Here is a picture of snow rollers as seen yesterday (4/10/20) in the Southern Sierra Nevada at an elevation of 8,700 feet. Snow rollers are rare and usually only a few inches wide. These snow rollers were up to two feet in diameter. Picture submitted by Brice Jury. #CAwx pic.twitter.com/FNsMHaNd2A
— NWS Hanford (@NWSHanford) April 11, 2020
The biggest changes to the snowpack were recorded over the Southern Sierra where liquid snow equivalent snowpack increased by 32%! The heavy accumulation even created some massive snow rollers. Percent of normal snowpack in the Southern Sierra jumped from 44% of normal on April 4th to 60% of normal on April 11th.
The recent accumulation has melted slightly in the days following the storm, but overall in the Sierra snowpack increased about 10%, compared to normal snowpack, from just the one storm system to 63%. For comparison, last year the Sierra snowpack measured in at 160% of normal, but in 2014, during California’s multi-year drought, snowpack on April 14th was 25% of normal.
— NWS Bay Area (@NWSBayArea) April 14, 2020
The recent storm has left the Central Valley and surrounding areas greener and whiter, depending on elevation.
Colorado and the Rockies have also recently added to the already impressive snowpack out west, and even more is expected to pileup through Friday. Colorado’s snow water equivalent (SWE) is 90% of normal or above in 7 out of the 8 basins that are monitored. The lone basin below 90%, the Upper Rio Grande Valley, has 83% of its typical SWE.
Overall, snowpack across the West, especially in the Rockies, is near or above average for mid-April. The Sierra and Southern Cascades of Oregon are the exceptions, bewteen 60-75 % of normal to date. The mountains of Arizona and New Mexico however, remain well below average.