A vigorous upper level low pressure system and associated cold front combined to produce strong thunderstorms with locally heavy rain over south central Arizona during the afternoon and evening hours on September 27th. During the early afternoon, a severe squall line moved east across south central Arizona, bringing damaging winds. Shortly thereafter, heavy rains developed which initially led to both urban flooding and flash flooding; as the afternoon progressed more significant areal flooding developed over the central deserts which prompted the issuance of multiple Areal Flood Warnings. Numerous Flash Flood Warnings and Urban and Small Stream Flood Advisories were issued for south central Arizona with this heavy rainfall event. No injuries were reported due to the flooding.

Flash Flood in MARICOPA, ARIZONA
From 27-SEP-14 15:00:00 to 27-SEP-14 19:30:00 (MST-7)
Location: SUNNYSLOPE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

During the early afternoon hours on September 27th, a line of strong thunderstorms moved east across the greater Phoenix metropolitan area. In addition to bringing strong wind, the storms produced very heavy rain with rain rates in excess of 2 inches per hour. The heavy rains affected North Mountain, and led to flash flooding along Interstate 17 about 1 mile north of the Metro Center Mall. According to a trained weather spotter, at about 1530MST, flash flooding caused 3 to 4 feet of water to accumulate under the underpass of Interstate 17, creating extremely hazardous conditions for motorists. Fortunately, no injuries were reported as a result of the flooding. Although a Flash Flood Warning was not issued for the area, Urban and Small Stream Flood Advisories were in effect beginning at 1424MST and continuing through 1930MST.

Flood in MARICOPA, ARIZONA
From 27-SEP-14 15:00:00 to 27-SEP-14 20:30:00 (MST-7)
Location: GOODYEAR ARPT
Flood cause: Heavy Rain
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Broadcast Media

A line of very strong thunderstorms moved across the western portion of the greater Phoenix Metropolitan area during the early afternoon hours, affecting communities such as Litchfield Park, Avondale and Goodyear. The storms produced very heavy rainfall with rain rates in excess of 2 inches per hour and this led to significant, widespread urban flooding. According to a report from local broadcast media, the heavy rains flooded neighborhoods in Litchfield Park and Goodyear, especially in the areas near 156th Avenue and West Indian School Road. The flooding was reported at about 1600MST, and soon afterward an Areal Flood Warning was issued for the area. The warning remained in effect through 2030MST.

Flash Flood in MARICOPA, ARIZONA
From 27-SEP-14 15:30:00 to 27-SEP-14 18:30:00 (MST-7)
Location: SCOTTSDALE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A line of severe thunderstorms moved east across the greater Phoenix area during the early afternoon hours on September 27th; in addition to gusty damaging winds the storms produced locally heavy rainfall with rain rates in excess of 2 inches per hour. The storms produced rainfall totals in excess of 2 inches across portions of Scottsdale which led to flash flooding, affecting streams and washes such as the Indian Bend Wash. According to a trained weather spotter, at 1608MST the Indian Bend Wash was reported to be flowing at least two feet deep over Osborn Road. Additionally, Miller Road from 2nd Street to Osborn Road had water up to the top of the curb. The flash flooding in Indian Bend Wash persisted into the late afternoon hours. No injuries were reported due to the flash flooding.

Heavy Rain in PINAL, ARIZONA
From 27-SEP-14 16:00:00 to 27-SEP-14 19:45:00 (MST-7)
Location: BAPCHULE
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Strong thunderstorms moved across the eastern portion of the greater Phoenix metropolitan area during the afternoon and evening hours on September 27th, and they produced locally heavy rain with peak rain rates in excess of 2 inches per hour. The heavy rains affected the community of San Tan Valley and led to significant stream and street flooding in the area. According to a trained weather spotter located about 2 miles southeast of San Tan Mountain, 1.05 inches of rain was measured in 30 minutes, beginning at about 1600MST. Washes in the area were reported to be running about 4 inches deep. Another trained weather spotter located 1 mile north of San Tan Valley measured 1 inch of rain in 30 minutes beginning at 1610MST, and the rain led to street flooding with water near the top of the curbs. The flooding resulted in the issuance of both Small Stream Flood Advisories and Flash Flood Warnings for the area.

Flood in PINAL, ARIZONA
From 27-SEP-14 19:30:00 to 27-SEP-14 22:30:00 (MST-7)
Location: APACHE JCT
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

Strong thunderstorms moved across the eastern portion of the greater Phoenix metropolitan area during the afternoon and early evening hours, and they affected communities such as Apache Junction. The stronger storms produced very heavy rain with rain rates in excess of 2 inches per hour at times. The heavy rain led to significant flooding of roads and streams in the area; according to the Department of Highways, at 2003MST State Route 88 was closed from Milepost 200 to Milepost 202 due to flooding. The reported flooding was about 2 miles northeast of Apache Junction. An Areal Flood Warning was issued for the area beginning at 1938MST and ending at 2230MST.

Heavy Rain in MARICOPA, ARIZONA
From 27-SEP-14 14:30:00 to 27-SEP-14 19:30:00 (MST-7)
Location: HELENA
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A line of powerful thunderstorms moved east across the greater Phoenix area during the early afternoon hours, followed by additional thunderstorm development which continued into the evening on September 27th. The stronger thunderstorms produced heavy rain with peak rain rates in excess of 2 inches per hour. The rain led to significant and widespread urban street flooding across the greater Phoenix metropolitan area, resulting in the issuance of both Urban and Small Stream Flood Advisories and Flash Flood Warnings. According to a trained weather spotter in Tempe, a storm total rainfall amount of 2.14 inches was measured as of 1720MST. Another trained spotter 2 miles west of Fountain Hills measured the exact same amount in a 3 hour period ending at 1728MST. At 1440MST, a trained spotter 2 miles southeast of Glendale reported flooded roadways with water covering the wheel wells of vehicles. At 1517MST, a trained spotter 4 miles south of Goldfield Ranch reported flooded roads, with some roads impassable. At 1625MST a trained spotter 3 miles northwest of Phoenix Sky Harbor Airport reported that the intersection of 24th Street and Thomas Road was flooded and impassable.

Flash Flood in MARICOPA, ARIZONA
From 27-SEP-14 14:30:00 to 27-SEP-14 19:30:00 (MST-7)
Location: PHOENIX
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Broadcast Media

A line of powerful thunderstorms moved east and across the central portion of the greater Phoenix metropolitan area during the early afternoon hours on September 27th. In addition to strong winds, the storms produced very heavy rain with peak rain rates in excess of 2 inches per hour. The heavy rain led to significant urban flooding and flash flooding across central Phoenix. According to a local broadcast media report, at 1511MST the heavy rains flooded the underpass at Interstate 17 and Grant Road, located about 1 mile northwest of the Arizona State Fairgrounds. The flooding caused the interstate to become impassable and created very hazardous driving conditions. Initially an Urban and Small Stream Flood Advisory was in effect for central Phoenix, however it was upgraded to a Flash Flood Warning at 1530MST. The warning remained in effect through 1830MST. Fortunately, no injuries were reported due to the flash flooding.

Heavy Rain in MARICOPA, ARIZONA
From 27-SEP-14 14:30:00 to 27-SEP-14 19:30:00 (MST-7)
Location: SCOTTSDALE
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A line of powerful thunderstorms moved across the greater Phoenix area during the afternoon hours on September 27th, and they affected communities such as Scottsdale. The storms produced very heavy rainfall with peak rain rates in excess of 2 inches per hour at times, and the rain led to significant urban flooding in Scottsdale. According to an amateur radio report, curb to curb street flooding was observed at the intersection of Pima and Thomas Roads, about 2 miles southeast of downtown Scottsdale. Additionally, a trained spotter 2 miles northeast of downtown Scottsdale reported curb to curb flooding with some areas impassable. The heavy rain created hazardous driving conditions for motorists during the evening rush hour.  Initially, at about 1430MST an Urban and Small Stream Flood Advisory was issued for the entire greater Phoenix metropolitan area; the advisory was upgraded to a Flash Flood Warning at 1530MST.