An active weather pattern set up over northern California from March 14-19, with a series of troughs passing over the region. The main impacts reported from these storms systems were moderate amounts of mountain and foothill snow, which lead to chain controls and travel delays.
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.
An active weather pattern set up over northern California from March 14-19, with a series of troughs passing over the region. The main impacts reported from these storms systems were moderate amounts of mountain and foothill snow, which lead to chain controls and travel delays. Light to moderate Valley rain and thunderstorms were forecast as well; however, no significant reports were received.
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 Mar 14, 2:54 AM PST, 8 hours 6 minutes earlier.
Area Forecast Discussion...CORRECTED National Weather Service Sacramento CA 354 AM PDT Sun Mar 14 2021 .SYNOPSIS... A weather system will move into northern California late Sunday and into Monday, bringing with it the next opportunity for Valley rain and mountain snow showers. Dry weather is forecast for Tuesday and Wednesday before renewed precipitation chances return on Thursday. && .DISCUSSION... Scattered to broken high clouds are traversing over northern California this early Sunday morning as the next storm system approaches the coast. The effects of these high clouds are already realized at the surface as temperatures are generally running a few/several degrees warmer compared to 24 hours prior. In the immediate short-term over the next 6-12 hours, weather-related impacts will remain minimal as we wait for the onset of precipitation. Upper level trough positioned west of California will dig south and east over the next 24 hours, and will bring with it our next chance of precipitation. Initially, rain and snow will develop in the afternoon hours across far northwest California, first impacting parts of Shasta, Tehama, and Glenn Counties in our area. As the evening and overnight hours progress, precipitation will expand south and east over the Valley and into the Sierra Nevada and southern Cascades. Winter Storm Warning goes into effect for the mountains of Shasta County, the southern Cascades and the northern Sierra at 5 pm PDT today, while a Winter Weather Advisory goes into effect for the Coastal Range at 5 pm PDT. While portions of the Coastal Range will likely see snow begin before 5 pm, the ever-increasing March sun angle as we approach the equinox plus the warmer pavement temperatures will likely prevent immediate snow accumulations on roadways until the sun lowers and temperatures cool. High resolution models advertise the heaviest precipitation overnight Sunday and into early Monday as the front pushes through northern California. Additionally, snow levels will plummet overnight with some minor snow accumulations as low as 1,000 to 1,500 ft in Shasta County, and 1,500 ft to 2,000 ft in the northern Sierra Nevada. It isn't completely out of the question that snow levels may drop below 1,000 ft around sunrise Monday in parts of Shasta County. That said, majority of accumulating snowfall will occur above 2,500 ft in Shasta County with 6 to 12 inches (locally higher), and above 3,000 ft in the southern Cascades and northern Sierra Nevada with 6 to 18 inches (locally 2 feet). Rain totals will generally range from 0.25 to 1.25 inches in the Valley and lower foothills. Motorists with mountain travel plans today should plan accordingly as road conditions will begin to deteriorate in the afternoon/evening hours from northwest to southeast. As always, travelers are encouraged to check with CalTrans for the updated road conditions. Precipitation coverage will decrease through the day on Monday across northern California. Ample cold air aloft and minor instability will provide opportunity for afternoon showers and isolated weak thunderstorm development across the Valley. With wet bulb temperatures at 925 mb (~2700 ft MSL) at/below 0 deg C on Monday afternoon, convective showers with even minor vertical growth will have the potential to drop small hail -- similar to the showers/thunderstorms experienced across portions of the area last week. Clearing skies and cold airmass will allow temperatures to drop off quickly Monday night and into Tuesday morning. Completely plausible some places in the Valley will see temperatures fall into the low 30s, possibly even upper 20s. The National Blend of Models already gives Redding Airport a 62 percent chance of falling to/below freezing. Temperatures will start to rebound on Tuesday as a weak ridge builds overhead with afternoon highs in the low 60s. Dry conditions will continue on Wednesday before the next opportunity for precipitation arrives overnight/early Thursday. // Rowe && .EXTENDED DISCUSSION (Thursday THROUGH Sunday)... Rossby analysis showing 4 wave pattern across NH Thursday with longwave off West Coast to progress, per upstream longwave position. Pacific frontal system modeled to spread widespread light to moderate precipitation into the CWA Thursday into Friday. Several short wave troughs progged to follow main baroclinic zone Saturday and Sunday. Best chances for post-frontal showers modeled in the foothills, mountains, and northern/central Sacramento Valley. High temperatures expected to be slightly below normal through the extended forecast period. PCH && .AVIATION... Pac fntl sys movs thru intr NorCal nxt 24 hrs. Dtrtg conds sprdg fm NW to SE acrs fcst area tda into tngt. Wdsprd MVFR with areas IFR and lcl LIFR omtns dvlpg aft 18z. Isold aftn tstms poss in lwr elev. Areas of Sly sfc wnd gsts to 25 kts in Cntrl Vly aft 00z Mon with SWly sfc wnd gsts up to 40 kts poss ovr hyr mtn trrn. && .STO WATCHES/WARNINGS/ADVISORIES... Winter Storm Warning from 5 PM this afternoon to 5 PM PDT Monday for Burney Basin / Eastern Shasta County-West Slope Northern Sierra Nevada-Western Plumas County/Lassen Park. Winter Weather Advisory from 5 PM this afternoon to noon PDT Monday for Mountains Southwestern Shasta County to Western Colusa County. Winter Storm Warning from 5 PM this afternoon to noon PDT Monday for Shasta Lake Area / Northern Shasta County. &&
4 winter storm, 2 winter weather. Local standard time, as filed.
Manzanita and Mineral COOP sites reported 14 and 11 inches new snow respectively.
Observers from CoCoRaHS reported located 2.5 E of Shingletown reported 8 inches of snow accumulation.
Caltrans reported 9 inches of new snow accumulation at Kingvale, 12 inches at Soda Springs and Eagle Lakes, and 10 inches at Donner Summit.
Ski resorts across the Sierra Nevada reported between 6 and 14 inches of new snow by 9AM March 15. Dodge Ridge reported 14 inches, Kirkwood and Sierra-at-Tahoe reported 12 inches, Bear Valley reported 10 inches, Squaw/Alpine reported 8 inches, and Sugar Bowl reported 7 inches.
Manzanita and Mineral COOP sites reported 3 and 1 inch new snow respectively.
Caltrans reported 8 inches of new snow accumulation at Kingvale, 16 inches at Soda Springs, 4 inches Eagle Lakes, and 18 inches at Donner Summit. These are the storm totals.
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, March 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: 951382, 951383, 951384, 951385, 951386, 951387.