Isolated severe thunderstorms developed over the northern Sierra Nevada with some large hail.
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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.
Isolated severe thunderstorms developed over the northern Sierra Nevada with some large hail.
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 1, 2:29 PM PST, 2 hours 56 minutes earlier.
Area Forecast Discussion National Weather Service Sacramento CA 329 PM PDT Tue May 1 2018 .SYNOPSIS... Drier and warmer this week except for a few showers and thunderstorms over the Sierra through Wednesday. && .DISCUSSION... At 3:30 pm, radar is showing scattered showers developing over the Sierra from around I80 southward, including some isolated thunderstorms near and just north of Yosemite. Convective activity is expected to increase further northward through the northern Sierra into the mountains of western Plumas County/Lassen Park as another disturbance drops southward from the Pacific Northwest later today into this evening. Isolated thunderstorms are also possible in those areas through the evening, with small hail and brief heavy rain the main issues. A few snow showers are possible at Sierra pass levels into this evening, potentially bringing an additional dusting of snow. As the disturbance exits, shower activity Wednesday will be limited to the Sierra crest south of Highway 50. Temperatures have warmed around 5-10 degrees so far this afternoon compared to yesterday. Highs in the upper 70s to lower 80s to the Valley and Delta are expected, with the warmest locations over the central and northern Sacramento Valley. Northerly winds in those areas should also keep overnight temperatures mild. Further warming and drying takes place through the rest of the week as ridging from the eastern Pacific takes hold. Highs Thursday are expected to be in the low 80s through the Central Valley, mid 80s by Friday. EK && .EXTENDED DISCUSSION (Saturday THROUGH Tuesday) An upper level trough will track through NorCal for the start of the extended period. This will bring a slight chance for light showers late Saturday and for Sunday to the higher elevation in the northern part of the CWA. A few rumbles of thunder can't be ruled out in the northern coastal range Saturday evening. Rain totals will remain very light with this system and snow levels will be high. As the trough pushes east a ridge will build in and we will see warm conditions for early next week. Monday will likely be the warmest day with a northerly wind in the north valley and we are expecting highs to make into the lower 90s in that area with mid to upper 80s else where in the valley. Dry and warm weather will continue on Tuesday. -CJM && .AVIATION... VFR conditions the next 24 hours at the TAF sites. Scattered showers over the mountains south of I-80 diminish by 6z, MVFR/IFR conditions in the vicinity of any showers. Breezy northerly winds 10-15 knots gusting to 20 knots diminish to 5-10 knots this evening switching to southerly. -CJM && .STO WATCHES/WARNINGS/ADVISORIES... None. &&
The Sacramento radar (KDAX), 153 km away, was scanning. The volume nearest the first event began at 01:25 UTC.
2 hail. Local standard time, as filed.
Hail covered the ground to a depth of just over 2 inches. Most of the hail was pea size, but the larger hailstones were as large as nickels and quarters. The hail for about 15 minutes.
Hail as large as nickels was reported.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2018Every state in 2018This day in weather historyWarnings in California, May 2018
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: 761276, 761278.