Flood, Riverside
- When
- August 9, 2:30 PM PST to 3:30 PM PST
- Where
- Riverside County, Hemet
- Reported by
- TRAINED SPOTTER
- Coordinates
- 33.744, -115.994 (the zone’s center; the record gives no point)
Flood and Damaging Wind in California, August 9, 1998
The circulation around strong high pressure over the southwestern United States fed moist unstable air into the mountains of southern California. Afternoon heating sparked a thunderstorm over the Riverside County mountains, which moved over the Hemet area dropping one inch of rain in just one half hour.
Where it happened
Every event with a place to put it; 1 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
- Tornadoes
- Tropical storms and surge
- Floods
- Wind
- Hail
- Winter weather
- Heat and drought
- Cold
- Fire, smoke and dust
- Marine and coastal
- Other
The toll
- Deaths
- 0
- Injuries
- 0
- Property damage
- None recorded
- Crop damage
- None recorded
- Events
- 2
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.
What happened
The episode as NWS SGX wrote it up.
The circulation around strong high pressure over the southwestern United States fed moist unstable air into the mountains of southern California. Afternoon heating sparked a thunderstorm over the Riverside County mountains, which moved over the Hemet area dropping one inch of rain in just one half hour. As the storm moved toward Moreno Valley and Riverside it became severe. Trees were uprooted in Moreno Valley, but the worst damage occurred in Riverside, where a motel lost a 30 by 90 foot section of its composite roofing and a tree snapped and fell on a car. The electric utility reported at least 2000 customers without power as a result of downed power lines.
The radar
The national radar mosaic for the moment the first event began.
Event by event
1 flood, 1 thunderstorm wind. Local standard time, as filed.
Thunderstorm Wind, Riverside
- When
- August 9, 3:15 PM PST to 4:15 PM PST
- Where
- Riverside County, Riverside
- Measured
- 65 kt (75 mph)
- Reported by
- NEWSPAPER
- Coordinates
- 33.950, -117.400
What these are
- Flood
- Flooding that develops more slowly than a flash flood: rivers leaving their banks, or water standing over land for an extended time.
- Thunderstorm Wind
- Winds from a thunderstorm of 50 knots (58 mph) or more, or lower winds that caused damage or casualties. Measured gusts are marked MG, estimated EG.
After NWS Directive 10-1605, the rules offices file Storm Data by.
The same day elsewhere
- Hail and Damaging Winds in Michigan, August 9 to 24, 1998
- Hail and Damaging Winds in Minnesota, August 9, 1998
- Damaging Winds and Lightning Strike in Oklahoma, August 9, 1998
- Flash Flood and Damaging Wind in Arizona, August 9, 1998
- Flash Flooding and Lightning Strike in Michigan, August 9, 1998
- Flash Flooding in Minnesota, August 9, 1998
- Hail and Damaging Winds in Minnesota, August 9, 1998
- Hail and Damaging Winds in Wisconsin, August 9, 1998
- Tornadoes and Flash Flood in Colorado, August 9, 1998
- Lightning Strike in Florida, August 9, 1998
- Damaging Wind and Lightning Strike in Arkansas, August 9, 1998
- Damaging Winds in Oklahoma, August 9, 1998
More
Every storm in California in 1998Every state in 1998This day in weather historyWarnings in California, August 1998
Sources
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: 5664004, 5664003.