Alert archive / California / Severe Thunderstorm Warnings in 2026
Severe Thunderstorm Warning 21, NWS Sacramento, CA
NWS Sacramento, CA issued this severe thunderstorm warning at Apr 10, 2026, 4:08 PM PDT for Calaveras County, Tuolumne County, California. It was in force for 25 min. No storm report in the archive falls inside the area while it was in force.
The area
The outline as issued.
The facts
- Issued
- Apr 10, 2026, 4:08 PM PDT (23:08 UTC)
- Expired
- Apr 10, 2026, 4:33 PM PDT
- In force
- 25 min
- Issued by
- NWS Sacramento, CA
- Area
- Storm-based polygon
- Hail
- 1.0 in
- Wind
- 50.0 mph
Counties Calaveras County, CA, Tuolumne County, CA
The radar
The Sacramento radar (KDAX), 131 km from the middle of the area, began a volume at 23:09 UTC, the scan nearest the moment this went out.
Open the radar archive at this moment
The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.
Did it verify
Not verified. The Iowa Environmental Mesonet's Cow found no qualifying storm report inside this severe thunderstorm warning while it was in force. That is not proof nothing happened: reports are thin where few people live.
Cow counts a report within 15 km of the polygon while the warning was in force: a tornado for a tornado warning; hail of 1 inch or more, a gust of 58 mph or more or wind damage for a severe thunderstorm warning; a flash flood report for a flash flood warning.
The nearest sounding before it
Oakland, CA (KOAK), launched 12:00Z, 11.1 hours before the alert went out and 176 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 6 J/kg
- Mixed-layer CIN
- 0 J/kg
- Mixed-layer LCL
- 551 m above ground
- 0-6 km bulk shear
- 31 kt
- 0-1 km storm-relative helicity
- -3 m²/s²
- 0-3 km storm-relative helicity
- 42 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
058 WUUS56 KSTO 102308 SVRSTO CAC009-109-102345- /O.NEW.KSTO.SV.W.0021.260410T2308Z-260410T2345Z/ BULLETIN - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Warning National Weather Service Sacramento CA 408 PM PDT Fri Apr 10 2026 The National Weather Service in Sacramento has issued a * Severe Thunderstorm Warning for... Central Tuolumne County in northern California... Eastern Calaveras County in northern California... * Until 445 PM PDT. * At 408 PM PDT, a severe thunderstorm was located near Jupiter, or 8 miles northeast of Sonora, moving northeast at 30 mph. HAZARD...Quarter size hail. SOURCE...Radar indicated. IMPACT...Damage to vehicles is expected. * Locations impacted include... Calaveras Big Trees SP, Jupiter, Dorrington, Mono Vista, Phoenix Lake-Cedar, Phoenix Lake-Cedar Ridge, Twain Harte, Mi- Wuk Village, Soulsbyville, and Arnold. PRECAUTIONARY/PREPAREDNESS ACTIONS... For your protection move to an interior room on the lowest floor of a building. && LAT...LON 3799 12028 3808 12038 3830 12033 3819 12002 TIME...MOT...LOC 2308Z 210DEG 24KT 3808 12029 HAIL THREAT...RADAR INDICATED MAX HAIL SIZE...1.00 IN WIND THREAT...RADAR INDICATED MAX WIND GUST...<50 MPH $$ KF
3 follow-up statements
180 WWUS56 KSTO 102316 SVSSTO Severe Weather Statement National Weather Service Sacramento CA 416 PM PDT Fri Apr 10 2026 CAC009-109-102345- /O.CON.KSTO.SV.W.0021.000000T0000Z-260410T2345Z/ Tuolumne CA-Calaveras CA- 416 PM PDT Fri Apr 10 2026 ...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 445 PM PDT FOR NORTH CENTRAL TUOLUMNE AND EASTERN CALAVERAS COUNTIES... At 415 PM PDT, a severe thunderstorm was located over Jupiter, or 10 miles south of Calaveras Big Trees SP, moving northeast at 30 mph. HAZARD...Quarter size hail. SOURCE...Radar indicated. IMPACT...Damage to vehicles is expected. Locations impacted include... Calaveras Big Trees SP, Jupiter, Dorrington, Arnold, and Phoenix Lake-Cedar Ridge. PRECAUTIONARY/PREPAREDNESS ACTIONS... For your protection move to an interior room on the lowest floor of a building. && LAT...LON 3806 12025 3812 12033 3830 12033 3819 12002 TIME...MOT...LOC 2315Z 210DEG 24KT 3813 12026 HAIL THREAT...RADAR INDICATED MAX HAIL SIZE...1.00 IN WIND THREAT...RADAR INDICATED MAX WIND GUST...<50 MPH $$ KF
222 WWUS56 KSTO 102329 SVSSTO Severe Weather Statement National Weather Service Sacramento CA 429 PM PDT Fri Apr 10 2026 CAC009-109-102345- /O.CON.KSTO.SV.W.0021.000000T0000Z-260410T2345Z/ Tuolumne CA-Calaveras CA- 429 PM PDT Fri Apr 10 2026 ...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 445 PM PDT FOR NORTH CENTRAL TUOLUMNE AND NORTHEASTERN CALAVERAS COUNTIES... At 429 PM PDT, a severe thunderstorm was located near Calaveras Big Trees SP, moving northeast at 30 mph. HAZARD...Quarter size hail. SOURCE...Radar indicated. IMPACT...Damage to vehicles is expected. Locations impacted include... Calaveras Big Trees SP and Dorrington. PRECAUTIONARY/PREPAREDNESS ACTIONS... For your protection move to an interior room on the lowest floor of a building. && LAT...LON 3815 12019 3818 12029 3829 12029 3822 12009 TIME...MOT...LOC 2329Z 210DEG 24KT 3821 12020 HAIL THREAT...RADAR INDICATED MAX HAIL SIZE...1.00 IN WIND THREAT...RADAR INDICATED MAX WIND GUST...<50 MPH $$ KF
800 WWUS56 KSTO 102333 SVSSTO Severe Weather Statement National Weather Service Sacramento CA 433 PM PDT Fri Apr 10 2026 CAC009-109-102343- /O.CAN.KSTO.SV.W.0021.000000T0000Z-260410T2345Z/ Tuolumne CA-Calaveras CA- 433 PM PDT Fri Apr 10 2026 ...THE SEVERE THUNDERSTORM WARNING FOR NORTH CENTRAL TUOLUMNE AND NORTHEASTERN CALAVERAS COUNTIES IS CANCELLED... The storm which prompted the warning has weakened below severe limits, and no longer poses an immediate threat to life or property. Therefore, the warning has been cancelled. LAT...LON 3815 12019 3818 12029 3829 12029 3822 12009 TIME...MOT...LOC 2332Z 210DEG 24KT 3823 12018 $$ KF
What forecasters said that day
The local office's own words before this severe thunderstorm warning went out, 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 this severe thunderstorm warning went out at Apr 10, 11:39 AM PDT, 4 hours 29 minutes earlier. Its key messages:
- Cooler temperatures and active weather through the weekend with rain, strong to severe thunderstorms, gusty winds, and mountain snow.
- Winter Storm Warning in effect for the Sierra and Southern Cascades Friday evening through Sunday evening.
Area forecast discussion, Apr 10, 11:39 AM PDT, 4 hours 29 minutes before
Area Forecast Discussion National Weather Service Sacramento CA 1139 AM PDT Fri Apr 10 2026 For additional details on weather and expected impacts over the next 7 days, please visit weather.gov/sto/briefing. .KEY MESSAGES... - Cooler temperatures and active weather through the weekend with rain, strong to severe thunderstorms, gusty winds, and mountain snow. - Winter Storm Warning in effect for the Sierra and Southern Cascades Friday evening through Sunday evening. && .DISCUSSION... ...Today through the Weekend... Current upper air pattern has a 500mb trough off the coast of California moving onshore today and through the weekend. Southerly flow of instability and moisture has helped develop showers and storms within the forecast area, with continued chances for storms this afternoon and evening. Soundings indicate low LCL, CAPE indices around 800-1500 J/kg, weak low level shear, and long CAPE through the atmosphere. This type of set up brings the chance for large hail (1 inch plus), accumulating hail, strong winds, moderate rainfall rates (locally heavy), and brief weak tornadoes. Currently this morning, we have had a few pulse/multi cellular storms develop along the foothills/valley with a report of accumulating hail east of the Orville, CA area. Latest CAMS have continued development through the remainder of the afternoon and evening, with the prime time for thunderstorm activity this afternoon and early evening when speed shear, directional shear, and instability is at its peak. Continued chances for strong to potential severe storms again Saturday and into Sunday as the upper level system moves through CA. If you are headed out, keep an eye on the skies and have a way to receive watches, warnings, and statements today and through the weekend. As the system moves onshore and we filter in cooler air aloft, precipitation changes over to snow within the mountains. Latest NBM has kept the forecasted snow totals roughly the same, with slightly lower snow levels Sunday. A Winter Storm Warning is in effect from this evening through Sunday evening for elevations above 4500 feet. Snow levels today will be above 6000 feet and lower toward 4000-5000 feet by Sunday. Heaviest snow rates and lowest snow levels are expected to be from Saturday afternoon through Sunday where major impacts to mountain travel are anticipated. Mountain travel is discouraged this weekend. Heavy snowfall rates of 1-2 inches per hour are possible within the Sierra Saturday afternoon through Sunday. Gusty southerly winds are also forecasted, with the strongest on Saturday. The north/central Sacramento Valley, northeast foothills and Sierra Crest will see the strongest winds of 35-45mph. We will continue to monitor the trends in the forecast to see if a product will be needed for the winds. ...Next Week... A return to drier and warmer temperatures early to mid next week as a ridge of high pressure builds into the region. How amplified the ridge becomes is uncertain as latest guidance from the NBM suggests the ridge flattening out mid to late week. This would bring the chance for isolated showers and a few snow showers within the mountains. Amounts, timing, and development of any potential system mid to late next week is uncertain at this time with confidence being low. && .AVIATION... MVFR conditions are expected over the next 24 hours, with periods of IFR in and around any thunderstorm activity. Showers and storms will continue to move through the region through the weekend. Winds, in and around thunderstorms may become erratic with direction changes and quick speed changes. Otherwise, surface winds will be out of the south for sites around Sacramento through RDD and RBL. MOD and SCK will see winds out of the NW. Surface winds will be around 10-12kts, with periodic gusts to 20kts in RDD and RBL. Winds will be on the stronger side tomorrow in the northern Sacramento Valley, with gusts up to 45mph at times. && .STO WATCHES/WARNINGS/ADVISORIES... Winter Storm Warning from 5 PM this afternoon to 11 PM PDT Sunday for West Slope Northern Sierra Nevada-Western Plumas County/Lassen Park. &&
In the hours before
Local storm report, Apr 10, 3:07 PM PDT, 1 hour 1 minute before
Preliminary Local Storm Report
National Weather Service Sacramento CA
307 PM PDT Fri Apr 10 2026
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0304 PM Hail Rio Vista 38.16N 121.69W
04/10/2026 E1.50 Inch Solano CA Trained Spotter
Trained spotter reports 1.5 inch / ping pong
hail in Rio Vista.
&&
strLocal storm report, Apr 10, 3:32 PM PDT, 36 minutes before
Preliminary Local Storm Report
National Weather Service Sacramento CA
332 PM PDT Fri Apr 10 2026
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0207 PM Hail Ripon 37.74N 121.13W
04/10/2026 E1.00 Inch San Joaquin CA Public
Public report of 1 inch hail, relayed via
broadcast media. Time estimated by radar.
&&
strThe office that day
Everything else NWS Sacramento, CA issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 9, 5:01 PM PDT | Severe Thunderstorm Warning | STO | Shasta, Tehama | 29 min |
| Apr 9, 5:22 PM PDT | Severe Thunderstorm Warning | STO | Shasta | 38 min |
| Apr 9, 6:52 PM PDT | Severe Thunderstorm Warning | STO | San Joaquin, Stanislaus | 38 min |
| Apr 9, 7:14 PM PDT | Severe Thunderstorm Warning | STO | San Joaquin, Stanislaus | 31 min |
| Apr 9, 7:39 PM PDT | Severe Thunderstorm Warning | STO | San Joaquin, Stanislaus | 36 min |
| Apr 10, 7:50 AM PDT | Severe Thunderstorm Warning | STO | Butte, Nevada, Plumas, Sierra, Yuba | 40 min |
| Apr 10, 1:55 PM PDT | Severe Thunderstorm Warning | STO | San Joaquin, Stanislaus | 35 min |
| Apr 10, 2:13 PM PDT | Severe Thunderstorm Warning | STO | Stanislaus | 15 min |
| Apr 10, 2:21 PM PDT | Tornado Warning | STO | San Joaquin, Stanislaus | 24 min |
| Apr 10, 2:38 PM PDT | Severe Thunderstorm Warning | STO | Stanislaus | 26 min |
| Apr 10, 2:40 PM PDT | Severe Thunderstorm Warning | STO | Calaveras, San Joaquin, Stanislaus | 35 min |
| Apr 10, 3:00 PM PDT | Severe Thunderstorm Warning | STO | Sacramento, San Joaquin, Solano, Yolo | 30 min |
Nearby
Severe Thunderstorm Warnings in California, 2026Every severe thunderstorm warning in 2026
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.