A late season storm brought showers, thunderstorms, and high elevation snow to the region. Thunderstorms brought heavy rain, copious amounts of small and accumulating hail, funnel clouds, and even a weak tornado to interior northern California.
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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 storm brought showers, thunderstorms, and high elevation snow to the region. Thunderstorms brought heavy rain, copious amounts of small and accumulating hail, funnel clouds, and even a weak tornado to interior northern California.
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 18, 3:00 AM PST, 7 hours earlier.
Area Forecast Discussion National Weather Service Sacramento CA 400 AM PDT Mon May 18 2020 .Synopsis... Rain showers, mountain snow showers, and thunderstorms possible today into Tuesday. Accumulating snow will cause mountain travel difficulties. Scattered thunderstorms today with isolated foothill and mountain storms on Tuesday. Breezy wind expected in the Central Valley today with gusty winds and poor visibility over higher terrain. Some lingering mountain showers Wednesday, dry and warmer Thursday into the weekend. && .DISCUSSION... Upper level low just off the coast along the Oregon and California drops southward and moves inland into the Bay area later today. This system will bring widespread precipitation into interior Northern California. Moderate showers are spreading across the area early this morning, and will become locally heavy as thunderstorms develop later today, especially north of I-80. Snow levels have dropped below pass levels, and at 3:30 am had reached around 6500 feet, with wet snow falling at Kingvale and accumulating snow at Donner Pass. Winter Storm Warning is on track, with 3 to 6 inches of snow down to around 6000 to 6500 feet with a foot or more over the higher peaks. Additional Valley rainfall will range from a quarter of an inch over the San Joaquin valley to over an inch for the north end of the Valley. The foothills should generally see another half inch to an inch. Locally, thunderstorms will likely bring higher amounts. A Flash Flood Watch remains in effect through 9 pm due to the potential of very heavy rainfall associated with thunderstorms. CAMs models show strongest ones develop over the eastern end of the Valley and foothills from around Chico Chico northward. The storms over Shasta County will be slow moving with a convergence area developing. This will increase the chances for flooding. There is also the potential for debris flows in burn areas, both in Shasta and Butte counties. In addition to heavy rain, large amounts of small hail are a threat. Shear becomes more limited through the day and may limit the development of stronger rotating cells. Temperatures will remain cool, generally peaking in the 60s across the Valley. As the low moves further south Tuesday the region will see less shower activity but some lingering chances will still remain, mainly over higher terrain. There is a slight chance of afternoon thunderstorms ...mainly over the western slopes of the Sierra and foothills. Temperatures look a little warmer, reaching the low 70s in the Valley. Wednesday a weak ridge will try to build over Northern California. Dry weather with warmer temperatures and mostly sunny skies can be expected. The exception is for some afternoon showers over the northern Sierra and southern Cascades. EK && .EXTENDED DISCUSSION (Friday THROUGH Monday)... Short wave trough brushes across NE portions of CA Friday but models keep associated precip outside of the CWA. Upper ridging then builds in over the weekend persisting into Monday. This will result in dry weather with warming temperatures. Above normal highs expected Sat/Sun, rising to about 10 degrees above normal Monday. && .AVIATION... In Cntrl Vly, areas MVFR/IFR poss in shwrs nxt 24 hrs. Areas of Sly sfc wnd gsts to 25 kts thru 03z Tue. Ovr fthls/mtns wdsprd MVFR/IFR with areas LIFR obscrg trrn. Areas S-W sfc wnd gsts up to 45 kts. Sn lvls 055-065 AMSL. Sct tsra/tsrags poss til 03z Tue. && .STO WATCHES/WARNINGS/ADVISORIES... Winter Storm Warning until midnight PDT tonight for Western Plumas County/Lassen Park. Flash Flood Watch from 10 AM PDT this morning through this evening for Central Sacramento Valley-Motherlode-Mountains Southwestern Shasta County to Western Colusa County-Northeast Foothills/Sacramento Valley-Northern Sacramento Valley-Northern San Joaquin Valley-Shasta Lake Area / Northern Shasta County- Southern Sacramento Valley-West Slope Northern Sierra Nevada- Western Plumas County/Lassen Park. Winter Storm Warning until 5 PM PDT Tuesday for West Slope Northern Sierra Nevada. &&
The Beale AFB radar (KBBX), 131 km away, was scanning. The volume nearest the first event began at 17:58 UTC.
2 flood, 1 tornado, 1 funnel cloud, 1 lightning. Local standard time, as filed.
Between 10am and 11am local law enforcement received a call from civilians that flooding was occurring at Jewell and Westside Rd. Additional reports from the public via social media show roadway and low land flooding across Redding.
California Highway Patrol reported flooding on one lane of the freeway at state route 99 north and state route 120 east interchange due to isolated thunderstorm.
This is an update to Ione funnel cloud local storm report that was previously sent. A member of the public reported a brief tornado near Ione from 12:21 pm to 12:26pm on May 18, 2020. Location and timing are approximate.
A member of the public sent pictures and video of what appears to be a possible funnel cloud. The person looked to be near Pleasant Grove and was looking to the southeast, about 10 miles from Roseville. Location is not approximate.
Local media reported that a man's home was struck by lightning on the afternoon of May 18. Media crews posted photos and video footage of damage to the owner's home which was estimated to be at least five thousand dollars worth of damage.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2020Every state in 2020This day in weather historyThe tornado archive for California, 2020Warnings in California, May 2020
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: 898108, 898109, 898112, 898110, 898126.