Thunderstorms developed across portions of south central Arizona, including the greater Phoenix area, during the late evening hours on August 10th. The storms got a late start due to early morning convection that helped to stabilize the atmosphere and delay new thunderstorms from forming. Thunderstorms ranged from the far western deserts, including Buckeye, through Scottsdale and into the higher terrain to the northeast of Arizona including the areas around Saguaro Lake. The storms brought typical monsoonal weather hazards, including gusty and damaging winds to near 60 mph, very heavy rain with peak rain rates well over one inch per hours, flash flooding and dense blowing dust. At 2245MST the public reported near zero visibility in a dust storm over far north Scottsdale. At the same time, members of the public witnessed vehicles that were stuck and flooded on dirt roads 7 miles northwest of Saguaro Lake and near Sycamore Creek. In addition, a dust storm occurred late in the evening over the northern portion of the greater Phoenix area.

Flash Flood in MARICOPA, ARIZONA
From 10-AUG-18 23:30:00 to 11-AUG-18 01:30:00 (MST-7)
Location: CLEARWATER HILLS
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Thunderstorms with heavy rain developed over the central portions of the greater Phoenix area during the late evening hours on August 10th. Peak rain rates with the stronger storms were in excess of one inch per hour and the heavy rain in an urban environment resulted in some flash flooding along Highway 51 west of Paradise Valley and north of Camelback Road. At midnight, or 0000MST, a Phoenix public resident reported roaring waters flowing down a wash behind her house. The home was located behind East Myrtle Avenue and along Highway 51. No accidents or injuries were reported due to the swiftly flowing wash. A Flash Flood Warning was issued for the area at 2331MST and it remained in effect through 0130MST the following morning.

Thunderstorm Wind in MARICOPA, ARIZONA
From 10-AUG-18 23:50:00 to 10-AUG-18 23:55:00 (MST-7)
Location: LITCHFIELD PARK
Magnitude: 56.00 EG
Property damage: 6.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorms with gusty and damaging outflow winds developed during the late evening hours across the western portion of the greater Phoenix area and affected communities such as Avondale and Litchfield Park. At about 2350MST, two trained spotter located about 2 miles southeast of Litchfield Park reported that trees were downed by gusty outflow winds. The winds were estimated to be as high as 65 mph. One spotter was located near the Palm Valley Golf Club and the other was near the intersection of Thomas Road and Dysart Road, next to the Palm Valley Elementary School. No injuries were reported due to the falling trees.

Dust Storm in NORTH PHOENIX/GLENDALE, ARIZONA
From 10-AUG-18 22:30:00 to 10-AUG-18 22:50:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Thunderstorms with strong gusty outflow winds developed across northern portions of the greater Phoenix metropolitan area during the late evening hours on August 10th. Some of the stronger storms generated gusty outflow winds in excess of 40 mph that stirred up dense blowing dust and created dust storm conditions. Among other locations, the dust storm affected far north Scottsdale in the area north of Bell Road and east of Highway 51. At 2244MST a member of the public reported near zero visibility in a dust storm near the intersection of Tatum Boulevard and Grovers Avenue. A Dust Storm Warning was in effect at the time of the report.

Flash Flood in MARICOPA, ARIZONA
From 10-AUG-18 23:00:00 to 11-AUG-18 01:30:00 (MST-7)
Location: SCOTTSDALE
Flood cause: Heavy Rain
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Thunderstorms with very heavy rain developed across portions of the greater Phoenix area, including the communities of Paradise Valley and Scottsdale, during the late evening hours on August 10th. The stronger storms produced intense rain with peak rain rates in excess of one inch per hour; the heavy rain led to flash flooding down the Indian Bend Wash in Scottsdale. According to a local emergency manager, at 2340MST flash flooding down the Indian Bend Wash was observed about 2 miles east of Paradise Valley, or just north of the intersection of Hayden Road and McDonald Drive. The manager indicated that there were road closures in the area due to the flooding and said that the flooding was a combination of the very heavy rain and SRP releases into the wash from the Arizona Canal. A Flash Flood Warning was issued for the area at 2235MST and the warning remained in effect through 0130MST the following morning.

Flash Flood in MARICOPA, ARIZONA
From 10-AUG-18 22:30:00 to 11-AUG-18 01:30:00 (MST-7)
Location: FT MCDOWELL
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Thunderstorms with very heavy rain developed during the late evening hours over higher terrain areas to the northeast of Phoenix on August 10th. Peak rain rates with the stronger storms were in excess of 1 inch hour and sufficient to cause an episode of flash flooding northeast of Fountain Hills and north of Saguaro Lake. At 2245MST a report from the public was received indicating the presence of flash flooding about 7 miles north of Saguaro Lake. A vehicle driver sent a social media post that showed a truck ahead of him stuck in rushing water. Followers of the Arizona Jeep Club confirmed that vehicles were stuck in flooded dirt roads in the area near Sycamore Creek. The report did not indicate if swift water rescues were needed or undertaken. A Flash Flood Warning was issued for the area at 2235MST and the warning remained in effect through 0130MST the following morning.

Thunderstorm Wind in MARICOPA, ARIZONA
From 10-AUG-18 23:55:00 to 10-AUG-18 23:55:00 (MST-7)
Location: BUCKEYE MUNI ARPT
Magnitude: 50.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Late evening thunderstorms developed over the western portion of the greater Phoenix area on August 10th. Some of the storms produced strong gusty outflow winds that affected the community of Buckeye. At 2355MST the official AWOS weather station at the Buckeye Municipal Airport measured a wind gust to 58 mph. At about this time, similarly strong winds a bit to the east and in the Litchfield Park area downed a number of trees as reported by trained weather spotters.