Isolated to scattered thunderstorms continued over the mountains, deserts, and portions of the Inland Empire, producing flash flooding each afternoon and evening through the 7th, with a brief lull in activity on the 1st. The hot spots on the 3rd were in the San Diego and Riverside County mountains, as well as the Coachella Valley. Storms in the Idyllwild/Pine Cove area produced flash flooding along Highway 243 and hail up to one-half inch. The Palm Springs area experienced flooding due to runoff from storms in the adjacent mountains, closing Araby Drive. Mountain storms also resulted in a flash flood and debris flow that raced down Tahquitz Creek and flowed through the Tahquitz Creek golf resort, closing Cathedral Canyon Drive at the Whitewater Wash. Areas in Riverside County also received accumulating small hail and severe winds from collapsing thunderstorms. Activity on the 4th and 5th favored similar areas, with more flash flooding. Runoff from storms over the Mountain Fire burn area in the San Jacinto Mountains resulted in a flash flood and debris flow 2 feet deep and 20 feet wide across Golf Club Drive in Cathedral City. Heavy rain also caused flooding on Highway 74 at McCall Road in Idyllwild, as well as Interstate 8 between Willows Road and Japatul. On the 6th, mud and water covered Highway S2 near the SR 79 intersection, closing that road due to multiple vehicles stuck in the mud. Pea to dime sized hail and damaging winds also accompanied these storms. Heavy rain caused minor road flooding in the Pine Valley area, with 1 to 2 inches of water flowing over several roadways. Highway 247 at Bessemer Mine Road had a 50-foot wide area of fast-moving water flowing across it, just east of Lucerne Valley. On the 7th, heavy rain near Forest Falls resulted in the normally dry Mill Creek running 2 feet deep and about 50 feet wide, stranding campers on one side of the creek. In San Diego County, there were 5 or 6 spots of water running across Highway 94 between Shockey Truck Trail and Sheridan Road with a maximum water depth of 6 inches. Waves of water up to 8 inches deep, with mud and debris, flowed rapidly over Highway 78 a few miles east of Julian. Highway 78 was impacted again as it dropped down into the desert, with 3 to 8 inches of water, in an area approximately 75 yards wide, flowing across the highway. Golf Club Drive in Cathedral City was closed again due to flooding from the Whitewater Wash.

Hail in RIVERSIDE, CALIFORNIA
From 03-SEP-13 14:30:00 to 03-SEP-13 15:30:00 (PST-8)
Location: PINE COVE
Magnitude: 0.88 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Trained Spotter

The spotter was in Idyllwild traveling on Highway 243 to Pine Cove. There was 2 deep of 0.5 hail and 1-3 of water flowing across Highway243. Broken tree branches were all over the roadway from hail damage. A nearby COOP observer reported that the roads turned white, all covered with accumulating hail.

Flash Flood in RIVERSIDE, CALIFORNIA
From 03-SEP-13 14:30:00 to 03-SEP-13 15:30:00 (PST-8)
Location: MOUNTAIN CENTER
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

CHP reported water flowing across the roadway along state route 74 E / state route 371 in Mountain Center. The road is impassable.

Flash Flood in RIVERSIDE, CALIFORNIA
From 03-SEP-13 13:30:00 to 03-SEP-13 16:30:00 (PST-8)
Location: CATHEDRAL CITY
Flood cause: Heavy Rain / Burn Area
Property damage: 100.00K
Crop damage: 0.00K
Reported by: Other Federal Agency

The USGS stream gauge on Palm Canyon Creek reported a 3.19 ft. rise. The gauge peaked at 1400 PST. Downstream from the gauge, broadcast media reported Araby Drive in Palm Springs was shut down due to a wall of water that passed through the area. CHP reported Golf Club Drive was closed at the wash due to flooding. Media also reported a flash flood and debris flow 2 feet deep and 20 feet wide flowing across Golf Club Drive. Cathedral Canyon Drive was closed at Whitewater Wash due to flooding and debris flows. The public also reported a flash flood and debris flow down Tahquitz Creek through the Tahquitz Creek Golf Resort.

Thunderstorm Wind in SAN DIEGO, CALIFORNIA
From 04-SEP-13 14:30:00 to 04-SEP-13 16:00:00 (PST-8)
Location: BARRETT JCT
Magnitude: 61.00 MG
Property damage: 0.50K
Crop damage: 0.00K
Reported by: RAWS

The Barrett RAWS measured a gust of 70 mph between 1350 and 1450 PST from a collapsing nearby thunderstorm. These winds were responsible for one small tree down, as well as branches and debris on Barrett Lake Road.

Thunderstorm Wind in SAN DIEGO, CALIFORNIA
From 05-SEP-13 12:30:00 to 05-SEP-13 13:30:00 (PST-8)
Location: GUATAY
Magnitude: 38.00 MG
Property damage: 8.00K
Crop damage: 0.00K
Reported by: Mesonet

The Guatay mesonet station reported peak wind gusts of 38 and 44 mph between 1230 and 1250 PST due to a nearby thunderstorm. County representatives reported several trees down blocking roadways in nearby Pine Valley. San Diego Gas and Electric also reported a few power poles down, leading to outages.

Thunderstorm Wind in SAN DIEGO, CALIFORNIA
From 05-SEP-13 12:30:00 to 05-SEP-13 13:30:00 (PST-8)
Location: JULIAN
Magnitude: 51.00 MG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Mesonet

The Warners mesonet station reported wind gusts of 52 and 59 mph between 1240 and 1310 PST due to a thunderstorm. Nearby, the Mataguay mesonet station recorded wind gusts of 56 and 58 mph between 1240 and 1300 PST. A san diego county official reported trees down on Valley View and Deer Creek Trail Roads.

Flash Flood in RIVERSIDE, CALIFORNIA
From 05-SEP-13 13:30:00 to 05-SEP-13 16:30:00 (PST-8)
Location: IDYLLWILD
Flood cause: Heavy Rain / Burn Area
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

California Highway Patrol reported a debris flow on Highway 74 at McCall Park Road. The water cleared out soon after and left behind debris on the road...such as rocks and sticks. The nearby Keenwild mesonet recorded 0.47 inches of rain during this time.

Hail in SAN DIEGO, CALIFORNIA
From 06-SEP-13 12:15:00 to 06-SEP-13 14:45:00 (PST-8)
Location: CLOVER FLAT
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

The public reported pea to quarter sized hail near Lake Morena on Facebook. The COOP observer a little further south in Campo reported heavy rain with a thunderstorm and 0.5 inch hail reducing visibility to 1/8 mile. Further north in Pine Valley, the public reported pea to dime size hail and 1 to 2 inches of water flowing over the road.

Flash Flood in SAN DIEGO, CALIFORNIA
From 06-SEP-13 12:30:00 to 06-SEP-13 13:30:00 (PST-8)
Location: WARNER SPGS
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

CHP reported Highway S2 was covered with mud, water and large boulders 3 miles southeast of the SR79 and S2 juncture. The mud was 2+ feet deep in places. A spotter reported on Facebook that he had seen 6-8 inches of water flowing through the same area. The S2 was closed from SR79 to S22. There were multiple reports of vehicles stuck in mud, including a fire truck that was en route to a lightning ignited fire. Pictures were submitted on Facebook. Further down Highway S22, the public reported up to quarter size hail. CHP also reported Borrego Springs Road was closed from San Pablo to Yaqui Pass due to flooding.

Flash Flood in SAN DIEGO, CALIFORNIA
From 06-SEP-13 13:00:00 to 06-SEP-13 14:30:00 (PST-8)
Location: PINE VLY
Flood cause: Heavy Rain
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A storm spotter reported flooding of roads in Pine Valley with two homeowners shoveling to divert waters from their homes. Further south in Lake Morena, a resident reported minor road flooding at Buckman Springs Road and Lake Morena Dr. His rain gauge measured 0.81 inches of rainfall in 1 hour. The nearby Campo COOP observer reported 0.94 inches of rain in 45 minutes during this time.

Thunderstorm Wind in SAN DIEGO, CALIFORNIA
From 06-SEP-13 13:30:00 to 06-SEP-13 14:00:00 (PST-8)
Location: DESERT LODGE
Magnitude: 56.00 MG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Mesonet

A Borrego Springs mesonet station recorded a peak wind gust of 64 mph during a thunderstorm. California Highway Patrol reported power lines down on Borrego Valley Road and Rango Way, blocking both directions of traffic.

Flash Flood in RIVERSIDE, CALIFORNIA
From 05-SEP-13 13:30:00 to 05-SEP-13 16:30:00 (PST-8)
Location: MOUNTAIN CENTER
Flood cause: Heavy Rain
Property damage: 500.00K
Crop damage: 0.00K
Reported by: Public

Significant heavy rain on the 3rd through 5th resulted in devastating flooding and debris flows in the canyon of the Riverside Mountains where the Zen Mountain Center is located. The Center sustained heavy damage from debris flows on the 4th and 5th and it is unclear which particular day was worse. On the 4th, approximately 3 to 5 feet of mud and rocks flowed through the retreat, half-burying cars and cabins. On the 5th, the second flow brought several more feet of mud and debris, fully burying a few cars. The flows broke plumbing pipes and uncovered buried phone lines. The various buildings sustained significant damage as well, with several feet of mud inside and water damage. Much of the walkways and common areas were unrecognizable due to the washouts.

Flash Flood in RIVERSIDE, CALIFORNIA
From 06-SEP-13 13:00:00 to 06-SEP-13 14:00:00 (PST-8)
Location: TEMECULA
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Roadway flooding 1/2 mile south of the SR79 and SR371 juncture. Several washes were flowing over the roadway with mud in the roadway.

Flash Flood in SAN BERNARDINO, CALIFORNIA
From 06-SEP-13 14:00:00 to 06-SEP-13 15:00:00 (PST-8)
Location: BALDWIN LAKE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

California Highway Patrol reported water quickly running across Bessemer Mine Road and Highway 247 about 50 feet wide.

Funnel Cloud in RIVERSIDE, CALIFORNIA
From 07-SEP-13 13:00:00 to 07-SEP-13 13:45:00 (PST-8)
Location: PERRIS
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

A ham radio operator reported 2 funnel clouds over Lake Perris.

Thunderstorm Wind in SAN DIEGO, CALIFORNIA
From 07-SEP-13 12:00:00 to 07-SEP-13 14:00:00 (PST-8)
Location: JULIAN
Magnitude: 49.00 MG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Mesonet

The Mataguay mesonet station recorded a peak wind gust of 56 mph between 1230 and 1250 PST. Nearby, a large tree limb was broken off and laying by Highway 79.

Flash Flood in SAN DIEGO, CALIFORNIA
From 07-SEP-13 13:00:00 to 07-SEP-13 15:00:00 (PST-8)
Location: BANNER
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

Water was flowing over Highway 78 near Banner with waves of water up to 8 inches deep. Mud and debris required removal by Caltrans.

Flash Flood in RIVERSIDE, CALIFORNIA
From 07-SEP-13 13:30:00 to 07-SEP-13 14:30:00 (PST-8)
Location: CATHEDRAL CITY
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

CHP reported Golf Club Drive closed at the wash due to flooding.

Flash Flood in SAN DIEGO, CALIFORNIA
From 07-SEP-13 15:00:00 to 07-SEP-13 17:00:00 (PST-8)
Location: BORREGO SPGS ARPT
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

An NWS employee reported water 4 to 8 inches deep flowing across Highway 78. The flow was estimated at 75 yards wide. The entire airport runway strip in Ocotillo was covered in areas of 1 to 3 inches of water. On the other side of Highway 78, water was flowing over Split Mountain Road in 2 locations. The water was draining from heavy rain over the entrance to Fish Creek and flowing 4 inches deep with mud 2 inches deep.

Flash Flood in RIVERSIDE, CALIFORNIA
From 07-SEP-13 14:15:00 to 07-SEP-13 16:15:00 (PST-8)
Location: MORENO VALLEY
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

CHP reported rocks and mud going across Lambs Canyon near SR79 and Gilman Springs Road. CHP also reported a mud slide and flooding in the #1 lane of Highway 60.

Flash Flood in SAN BERNARDINO, CALIFORNIA
From 07-SEP-13 13:00:00 to 07-SEP-13 15:00:00 (PST-8)
Location: FOREST FALLS
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

Mill Creek was running 2 feet deep and 50 feet wide. Campers were stranded on the north side of the creek.

Thunderstorm Wind in RIVERSIDE, CALIFORNIA
From 04-SEP-13 10:30:00 to 04-SEP-13 12:00:00 (PST-8)
Location: THOUSAND PALMS
Magnitude: 53.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

The Sky Valley mesonet station recorded sustained winds greater than 40 mph from 1030 to 1200 PST. During this time, two gusts of 61 mph were measured between 1030 and 1040 PST. Two gusts of 58 mph were also recorded between 1050 and 1100 PST.