The warm, unstable airmass that arrived at the end of September remained over interior central California through the 3rd day of October. However, cooler air arrived as an upper level trough moved over the area on the 4th.
Every event with a place to put it. Tap one for its entry below.
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 HNX wrote it up.
The warm, unstable airmass that arrived at the end of September remained over interior central California through the 3rd day of October. However, cooler air arrived as an upper level trough moved over the area on the 4th. The airmass remained moist and unstable until the 6th, and then began to dry out by the 8th due to high pressure over the central California interior. By the 10th, temperatures warmed to slightly above normal.
Events for the first week of this month included several incidents of roadway flooding in Kern County, and several days of thunderstorms in the San Joaquin Valley. On the 2nd, the California Highway Patrol reported of large rocks that created hazardous conditions on Highway 178 in the Kern River Canyon near Bodfish; in fact a Flash Flood Warning had been issued around 2:15 that afternoon due to slow moving thunderstorms in the area. Some strong thunderstorms developed near and west of Frazier Park around noon of October 2nd; Pine Mountain Club reported hail around one-half inch in diameter (smaller than dime size). During that evening, thunderstorms developed over Yosemite National Park, with some heavy rain over the area that caused nuisance flooding.
Showers and thunderstorms redeveloped during the afternoon and evening of the 3rd.|On the night of the 3rd, and into the early morning hours of the 4th, quite a few thunderstorms developed over the Hanford and Visalia areas, and spread northward into Fresno, Madera, and Mariposa. Lightning was quite frequent with these storms, and large hail about the size of halfdollars (1.25 inches) was reported near Mariposa around 1:00 AM on the 4th.
As for October 5th, there were quite a few showers, including snow showers in the higher elevations of the Southern Sierra Nevada, mainly above 7,500 feet. The snow accumulated up to 8 inches at Tioga Pass and 7 inches at Bishop Pass in the Southern Sierra Nevada, bringing a dangerous early season snowstorm to the popular hiking areas.
The storm that produced these showers subsequently moved into Arizona, triggering numerous thunderstorms. The storm also spawned eight tornadoes in northern Arizona, including near Flagstaff, during the early morning hours of the 6th; a new record for the most tornadoes in one day for Arizona.
The Los Angeles radar (KVTX), 58 km away, was scanning. The volume nearest the first event began at 20:31 UTC.
4 flood, 2 winter storm, 1 flash flood, 1 thunderstorm wind, 1 hail. Local standard time, as filed.
The Highway Patrol reported flooded lanes on I5 at Fort Tejon due to heavy rain and hail from thunderstorms.
CHP reported debris and mud in roadway on Caliente Bodfish Rd just south of intersection with Saddle Springs Road.
CHP reported large amount of rocks in road due to heavy rain CA HWY 178 just west of Old Kern Canyon road near Democrat Hot Springs.
Park official reported flooding between El Portal and Yosemite Valley. Some roads were temporarily closed due to flood debris.
Tree down and roof damage to a house in Yosemite Lakes Park.
Large hail to the size of half dollars reported at Woodland about 10 miles southeast of Mariposa.
Park official reported flooding and debris along the west side of Yosemite Valley.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2010Every state in 2010This day in weather historyWarnings in California, October 2010
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 2026-09-30. Each event’s entry at NCEI: 266307, 266319, 266310, 266311, 266315, 266313, 266312, 266320, 266321.