Thunderstorms moved from higher terrain north and southeast of the Phoenix metro area toward the lower deserts along multiple outflow boundaries. Multiple severe thunderstorm warnings were issued as storms were producing 50-60 mph winds. Stronger storms produced episodes of wind damage, impacting the greater Phoenix area from Deer Valley southeast through Tempe and into Queen Creek. Heavy rain also fell with the storms, which led to minor flooding impacts in many areas and localized flash flooding.

Thunderstorm Wind in MARICOPA, ARIZONA
From 20-AUG-20 19:33:00 to 20-AUG-20 19:35:00 (MST-7)
Location: SCOTTSDALE MUNI
Magnitude: 52.00 EG
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Strong thunderstorms, accompanied by gusty damaging outflow winds, moved off higher terrain and into portions of north Scottsdale during the evening hours on August 20th. Wind gusts estimated to be as high as 60 mph damaged a number of trees in the area. According to a trained weather spotter located about 3 miles west of north Scottsdale, at 1935MST strong outflow winds downed multiple trees near 64th street and Greenway Road. Some of the downed trees were reported to have fallen on some cars. Winds were estimated by radar and observations to be as high as 60 mph. At roughly the same time, a public report indicated that similarly strong winds uprooted a large tree near 40th street and Thunderbird road, about 6 miles west of north Scottsdale. No injuries were reported due to the downed trees.

Thunderstorm Wind in MARICOPA, ARIZONA
From 20-AUG-20 19:37:00 to 20-AUG-20 19:37:00 (MST-7)
Location: SCOTTSDALE MUNI
Magnitude: 52.00 EG
Property damage: 3.00K
Crop damage: 0.00K
Reported by: NWS Employee

Strong thunderstorms with associated gusty and damaging outflow winds moved off high terrain and into portions of north Scottsdale during the evening hours on August 20th. According to a National Weather Service employee, at 1937MST gusty outflow winds estimated to be as high as 60 mph blew down one tree and snapped another about 1 miles southeast of North Scottsdale and near the intersection of East Thunderbird Road and Frank Lloyd wright Boulevard. No injuries were reported due to the downed trees.

Thunderstorm Wind in MARICOPA, ARIZONA
From 20-AUG-20 19:47:00 to 20-AUG-20 19:50:00 (MST-7)
Location: KENDALL
Magnitude: 52.00 EG
Property damage: 30.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

Thunderstorms with gusty and damaging outflow winds developed across central portions of the greater Phoenix area during the evening hours on August 20th. Some of the stronger storms impacted areas a few miles to the northeast of Phoenix Sky Harbor Airport. According to the Phoenix Fire Department and Rescue unit, at 1947MST gusty winds estimated to be as high as 60 mph downed a large 100 foot tall pine tree onto a home located near the intersection of 32nd Street and Osborn Road, about 4 miles north of Sky Harbor. At roughly the same time, local broadcast media  reported power lines and trees downed near the intersection of 44th Street and McDowell Road, about 3 miles northeast of Sky Harbor. The media also had a video of a Palo Verde tree being blown across the parking lot of a new station about a half mile further to the south. Again, winds were estimated to be as high as 60 mph. There were no reports of injuries due to the strong winds or falling trees.

Thunderstorm Wind in MARICOPA, ARIZONA
From 20-AUG-20 19:55:00 to 20-AUG-20 19:59:00 (MST-7)
Location: TEMPE
Magnitude: 52.00 EG
Property damage: 30.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Strong thunderstorms developed on outflow boundaries over central and southeast portions of the greater Phoenix area during the evening hours on August 20th. Some of the stronger storms impacted the communities of Tempe and Ahwatukee Foothills. According to a report from local broadcast media, at 1959MST gusty outflow winds estimated to be at least 60 mph in strength blew down a very large tree onto an apartment complex in Tempe. The damage occurred just northwest of the intersection of Rural Road and the Superstition Freeway. The downed tree had a diameter of over one foot. Just a few minutes prior to that, a trained spotter located 4 miles east of the Ahwatukee Foothills reported multiple trees blown down and the largest tree had a diameter of greater than six inches. There were no reports of injuries at the apartment complex or due to the falling trees.

Thunderstorm Wind in MARICOPA, ARIZONA
From 20-AUG-20 19:12:00 to 20-AUG-20 19:12:00 (MST-7)
Location: PHOENIX DEER VLY ARP
Magnitude: 52.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorms with gusty and damaging outflow winds moved off of the higher terrain and into the northern portion of the Phoenix area during evening hours on August 20th. Some of the stronger gusts, estimated to be as high as 60 mph, produced damage in the Deer Valley area. According to a trained weather spotter, at 1912MST gusty winds blew down a metal awning near 27th Avenue and Deer Valley Road, just northwest of the intersection of Interstate 17 and the Loop 101. Additionally, the winds generated roof damage to several nearby structures, mainly in the form of shingles that were blown off.

Thunderstorm Wind in MARICOPA, ARIZONA
From 20-AUG-20 19:52:00 to 20-AUG-20 19:52:00 (MST-7)
Location: GLENDALE FRAM ARPT
Magnitude: 52.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Thunderstorms with gusty outflow winds moved into western portions of the greater Phoenix area during the evening hours on August 20th. At 1952MST, a wind gust of 60 mph was reported by the official AWOS weather station at the Glendale Municipal Airport in Glendale. There were no reports of damage associated with the strong wind gust.

Thunderstorm Wind in MARICOPA, ARIZONA
From 20-AUG-20 19:47:00 to 20-AUG-20 19:47:00 (MST-7)
Location: PARADISE VLY
Magnitude: 56.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Public

Thunderstorms with gusty damaging outflow winds moved off of the high terrain and into northeast portions of the greater Phoenix area, including Paradise Valley, during the evening hours on August 20th. According to a report from the public, at 1947MST strong outflow winds estimated to be in excess of 60 mph blew down a very large tree onto a Scottsdale Plaza resort unit. The damage occurred one mile northeast of Paradise Valley, or near the intersection of Indian Bend Road and North Scottsdale Road.

Thunderstorm Wind in MARICOPA, ARIZONA
From 20-AUG-20 19:56:00 to 20-AUG-20 19:56:00 (MST-7)
Location: PAPAGO AAF ARPT
Magnitude: 52.00 EG
Property damage: 20.00K
Crop damage: 0.00K
Reported by: Public

Thunderstorms with gusty and damaging outflow winds moved off high terrain to the northeast of Phoenix and into portions of Scottsdale during the evening hours on August 20th. According to a report from the public, at 1956MST gusty thunderstorm winds estimated to be at least 60 mph in strength downed a large tree near the intersection of 5th Street and Navajo Trail or about 1 mile southwest of Scottsdale. The downed tree landed on a house in the area however no injuries were reported. The report was received via social media.

Thunderstorm Wind in PINAL, ARIZONA
From 20-AUG-20 20:55:00 to 20-AUG-20 20:55:00 (MST-7)
Location: STANFIELD
Magnitude: 61.00 EG
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Public

Scattered thunderstorms, some with damaging outflow winds, developed to the southeast of Phoenix during the evening hours on August 20th. According to a report from the general public, a cluster of thunderstorms moved through the town of Stanfield at 2055MST; strong outflow winds generated by the storms produced significant roof and tree damage in the town. One of the damaged trees was a large 50 year old tree in town. Wind gusts were estimated to be as high as 70 mph. Stanfield is located about 12 miles west of the town of Casa Grande. There were no reports of injuries due to the strong damaging winds.

Thunderstorm Wind in MARICOPA, ARIZONA
From 20-AUG-20 17:25:00 to 20-AUG-20 17:25:00 (MST-7)
Location: CAREFREE
Magnitude: 51.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Thunderstorms with strong gusty outflow winds moved into the far northeast portions of the greater Phoenix area during the late afternoon hours on August 20th. At 1725MST an automated mesonet station at Horseshoe Reservoir measured a wind gust to 59 mph. There were no reports of damage due to the strong gust. The station was located about 16 miles northwest of Sunflower.

Flash Flood in MARICOPA, ARIZONA
From 20-AUG-20 22:00:00 to 21-AUG-20 02:00:00 (MST-7)
Location: MOBILE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

Thunderstorms, some with heavy rain, moved off the higher terrain and into the greater Phoenix area during the evening hours on August 20th. Stronger storms generated locally heavy rain with peak rain rates exceeding 1 inch per hour, which resulted in some flash flooding south of Phoenix. According to the Arizona Department of Highways, flash flooding that developed during the late evening led to the closure of State Route 238 east of Mobile shortly after midnight on August 21st. The highway was closed near 67th Avenue due to flooding at 0018MST. It should be noted that Highway 238 often floods during monsoon thunderstorm events, even with rainfall totals that are not especially heavy.

Thunderstorm Wind in PINAL, ARIZONA
From 20-AUG-20 20:09:00 to 20-AUG-20 20:10:00 (MST-7)
Location: MAGMA
Magnitude: 61.00 EG
Property damage: 90.00K
Crop damage: 0.00K
Reported by: Utility Company

Thunderstorms with gusty and damaging outflow winds developed across the southeast portion of the greater Phoenix area during the evening hours on August 20th. Some of the stronger storms generated microburst conditions that affected areas from Queen Creek southeast to Florence. According to a local utility company, at 2010MST a microburst generated winds estimated to be as high as 70 mph. The winds blew down 15 wooden power poles in San Tan Valley, about 6 miles southeast of Queen Creek. The poles were downed on Combs Road from Kenworthy Road to Schnepf Road. At about the same time, a trained weather spotter located 3 miles north of Florence reported that gusty winds snapped a power pole in two resulting in a power outage at a mobile home park. Additionally, the winds blew down many trees in the area including one with a diameter of about 12 inches. Winds were estimated to be in excess of 60 mph. There were no reports of injury due to the strong wind.