Scattered thunderstorms continued to develop across the central and southeast portions of the greater Phoenix metropolitan area during the very early morning hours on August 10th. Very heavy rainfall was associated with these storms, slightly unusual given the time of day. Peak rain rates were in excess of 2 inches per hours at times and the intense rainfall led to episodes of flash flooding and flooding, affecting communities such as Tempe, Mesa, Chandler and Queen Creek. From midnight into the very early morning, there were numerous reports from local law enforcement and department of highways personnel indicating the presence of flash flooding. Numerous roads were closed due to the flash flooding; washes were flowing and running over roads and urban street flooding was observed. No accident or injuries were reported due to the flash flooding.

Flash Flood in MARICOPA, ARIZONA
From 10-AUG-18 00:45:00 to 10-AUG-18 05:00:00 (MST-7)
Location: CHANDLER HGTS
Flood cause: Heavy Rain
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Thunderstorms with intense rainfall developed to the southeast of the greater Phoenix area during the very early morning hours on August 10th; peak rain rates with the stronger storms exceeded 2 inches per hour. The heavy rain led to flash flooding in the area around Queen Creek, including flooding in the Sonoqui Wash. At 0230MST, local law enforcement reported that Via Del Jardin was closed due to flash flooding along the Sonoqui Wash, about 2 miles west of Queen Creek. Later in the morning, at 0345MSt, local Queen Creek law enforcement reported that Power Road near Ocotillo Road was also closed due to flash flooding along the Sonoqui Wash. A Flash Flood Warning had been issued at about midnight for the area, but was allowed to expire at 0300MST. There were no reports of accidents or injuries due to the flash flooding.

Heavy Rain in MARICOPA, ARIZONA
From 09-AUG-18 23:45:00 to 10-AUG-18 03:00:00 (MST-7)
Location: MESA
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorms with very heavy rain developed over the eastern portion of the greater Phoenix area during the late evening hours on August 9th, and they continued into the early morning hours on the 10th. Peak rain rates with the stronger storms exceeded 2 inches per hour, and the heavy rain led to some street flooding over portions of the town of Mesa. According to a trained spotter located 2 miles northwest of Mesa, at 0004MST heavy rain led to street flooding near the intersection of the Rio Salado Parkway and Alma School Road. He indicated that the water was exceeding some of the curbs. A Flash Flood Warning was in effect at the time and remained in effect through 0300MST, however flash flooding was not reported at this location.

Flash Flood in MARICOPA, ARIZONA
From 09-AUG-18 23:45:00 to 10-AUG-18 03:00:00 (MST-7)
Location: CHANDLER HGTS
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorms with intense rainfall moved across the southeast portions of the greater Phoenix metropolitan area during the late evening hours on August 9th, and they continued to affect communities such as Chandler and Queen Creek into the early morning hours on August 10th. The stronger storms produced peak rain rates in excess of 2 inches per hour, which led to episodes of flash flooding near the town of Queen Creek. At 0001MST, a trained spotter 4 miles south of Higley and a few miles west of Queen Creek reported heavy street flooding near the intersection of Higley Road and Ocotillo Road. The flooding was significant enough that water was backing up into people's yards which is indicative of flash flooding. A Flash Flood Warning was issued just before midnight and was in effect for the area through 0300MST.

Flash Flood in MARICOPA, ARIZONA
From 10-AUG-18 00:05:00 to 10-AUG-18 03:00:00 (MST-7)
Location: HELENA
Flood cause: Heavy Rain
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Department of Highways

Thunderstorms with locally heavy rain developed across the southeast portion of the greater Phoenix metropolitan area during the late evening hours on August 9th, and the storms continued into the early morning hours on August 10th. The stronger storms produced intense rain with peak rain rates in excess of 4 inches per hour. Some of the heaviest rain fell in the community of Tempe, north of the Superstition Freeway, and led to episodes of early morning flash flooding. As an example of the intense rain that fell, at 0103MST an NWS employee near Baseline Road and the Loop 101 freeway measured 2.56 inches of rain within one hour and 40 minutes; most of the rain fell within one hour. Additionally, at Arizona State University, Flood Control District rain gage reports indicated that 2 inches of rain fell within 34 minutes ending at 0022MST.
At 0030MST, Arizona Department of Highways reported extensive flooding on Highway 60 under McClintock Road. This report came via Twitter. At 0038MST, Tempe police reported that McClintock Drive was closed between Broadway Road and Apache Boulevard due to flash flooding. This was about 1 mile southeast of Arizona State University. A bit later at 0130MST, Tempe police reported that Southern Avenue was closed between Rural Road and McClintock Drive due to flooding. At the same time, Tempe police indicated that Mill Avenue was closed between Broadway Road and 13th Street due to flooding. Finally, at 0138MST, Arizona Department of Highways reported that Highway 60 was closed at the Mill Avenue underpass due to flash flooding. A Flash Flood Warning was in effect at the time of the flooding and remained in effect through 0300MST.