A late season winter storm brought several inches of snow to Northern California. A Winter Weather Advisory was issued for elevations above 5,000 feet for the Southern Cascades and above 6,500 feet for the Northern Sierra Nevada.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS STO wrote it up.
A late season winter storm brought several inches of snow to Northern California. A Winter Weather Advisory was issued for elevations above 5,000 feet for the Southern Cascades and above 6,500 feet for the Northern Sierra Nevada.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Sacramento, CA wrote its last area forecast discussion before the first event at May 19, 1:22 PM PST, 10 hours 38 minutes earlier.
Area Forecast Discussion National Weather Service Sacramento CA 222 PM PDT Wed May 19 2021 .SYNOPSIS... Next weather system approaches today bringing cooler temperatures. Showers along with a few afternoon thunderstorms expected Thursday into the weekend, mainly over the mountains. The higher elevations will see some late season snowfall accumulations. Dry and milder weather returns early next week. && .DISCUSSION... Visible GOES-West imagery reveals a mix of clouds and sun across northern California this afternoon. The cloud cover is mainly confined to the higher elevations from Shasta County and points north while clear skies are overhead the Sacramento Valley. Despite the clear skies for a good portion of the area, temperatures are running a solid 5 to 10 deg F cooler than this time 24 hours ago. Additionally, locally breezy conditions have been observed in portions of western Shasta and Tehama counties this afternoon. As the afternoon progresses, expect an uptick in north/northwest winds for portions of the Sacramento Valley. Highs will peak in the 70s for most Valley communities, or about 4 to 8 deg F below middle/late May normals. Main story over the next several days will be a renewed chance of rain showers, snow showers, and even isolated thunderstorms (and thundersnow) across portions of northern California. Upper level low in western Washington state will drop south/southeast over the coming days, and will bring with it anomalously cold air throughout the atmospheric column. Precipitation chances will be largely focused in the mountains and foothills surrounding the Sacramento Valley. Unfortunately, most Valley communities will just remain dry and windy with elevated fire weather concerns. The highest probabilities for any showers in the Valley are capped around 15 percent in the far northern Sacramento Valley. Some minor accumulations are possible at pass levels in the Sierra, but the increasingly higher May sun angle will likely keep the road temperatures warm enough to prevent accumulations at the lowest snow levels (dropping to 3500 to 4000 ft). Additionally, locally-reduced visibilities will be possible in heavier snow showers/thundersnow. Hikers, campers, backpackers, or outdoor enthusiasts should take the necessary precautions from the winter- like elements; and when thunder roars, go indoors. That said, a Winter Weather Advisory is in effect for the southern Cascades at/above 5000 ft starting at midnight Thursday, and also for the Sierra at/above 6500 ft starting noon Thursday. In terms of precipitation timing, best chances will be both Thursday and Friday afternoons with the convective nature of the showers. Upper level low will slowly push south and east over the weekend, and will maintain shower/thunderstorm chances in the Sierra through at least Saturday afternoon/evening. // Rowe && .EXTENDED DISCUSSION (Sunday THROUGH Wednesday)... Upper level low will lift into the Rockies on Sunday and Monday. Depending on the timing of this low's exit, can't rule out the chance of some lingering showers in the Sierra on Sunday afternoon/evening. Weak upper level ridging then returns to northern California for the first half of the work week, and will allow Valley highs to return back into the 80s and near 90 on Monday. Ensemble guidance is trying to hint at a shortwave arriving to northern California around Tuesday/Wednesday, but plenty of uncertainty this far out if it does materialize. && .AVIATION... VFR conditions next 24 hours. Gusty westerly flow continues tonight with Valley gusts ranging from 15-30 kt, Delta gusts between 25-35 kt, and foothill and mountain gusts ranging from 15-35kt. Winds shift to the north after 9-12z Thursday with Valley gusts 20-30 kt. A late season system will bring mountain rain and snow showers with a chance of isolated afternoon thunderstorms generally after 03Z-06Z Thursday. && .STO WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from midnight tonight to 6 PM PDT Thursday for Burney Basin / Eastern Shasta County-Western Plumas County/Lassen Park. Winter Weather Advisory from noon Thursday to midnight PDT Thursday night for West Slope Northern Sierra Nevada. &&
1 winter weather. Local standard time, as filed.
A COOP observer near Soda Springs reported 3.6 inches of snow over a 24 hour period. Melted value was 0.34 inches.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2021Every state in 2021This day in weather historyWarnings in California, May 2021
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 962401.