A strong Pacific upper level low pressure system moved into Arizona during the morning hours on October 13th and triggered the development of widespread moderate to heavy showers across the south-central deserts. The heavy rain resulted in numerous episodes of flash flooding during the day. Southerly flow ahead of the low advected in some tropical moisture being shed from Tropical Storm Sergio which recently passed by to the south of Arizona, and this infusion of tropical moisture helped to support the very heavy rain that occurred. Many of the flash flood events took place across the entire greater Phoenix metropolitan area but some events took place as far south as Casa Grande and as far southwest as Gila Bend. Most of the flash flood events resulted in road closures due to the heavy rain and flooding. No reports of accidents or injuries were received. Multiple Flash Flood Warnings were issued during the days due to the flooding.

Flash Flood in MARICOPA, ARIZONA
From 13-OCT-18 08:30:00 to 13-OCT-18 14:00:00 (MST-7)
Location: MOBILE
Flood cause: Heavy Rain
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Department of Highways

A strong Pacific upper low moving into Arizona triggered numerous moderate to heavy showers across the south-central deserts during the morning hours on October 13th. The heavy rains led to an episode of flash flooding southwest of Phoenix, between the towns of Gila Bend and Maricopa. Heavy rain fell across some of the higher terrain locations southwest of Phoenix, such as the Maricopa Mountains, and runoff spilled across Highway 238 resulting in flash flooding and road closures. At 0942MST the Arizona Department of Transportation reported that Highway 238 was closing between Gila Bend and the town of Maricopa due to the flash flooding across the highway. A Flash Flood Warning was issued for the highway at 0830MST and it remained in effect through 1430MST.

Flash Flood in PINAL, ARIZONA
From 13-OCT-18 09:00:00 to 13-OCT-18 13:15:00 (MST-7)
Location: OLBERG
Flood cause: Heavy Rain
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Department of Highways

Widespread moderate to heavy showers developed across the lower deserts southeast of Phoenix during the morning hours on October 13th. Some of the heavy rain led to flash flooding south of Sacaton and north of Casa Grande. At 0916MST, the Arizona Department of Transportation reported that flash flooding stopped traffic on State Route 187 in areas between State Route 87 and State Route 387. The heavy rain was triggered by the approach of a strong Pacific low pressure system from the west, coupled with an infusion of deeper moisture shed from Tropical Storm Sergio which passed by earlier to the south of Arizona. A Flash Flood Warning was in effect at the time of the flash flooding and fortunately no accidents were reported.

Flash Flood in MARICOPA, ARIZONA
From 13-OCT-18 12:00:00 to 13-OCT-18 14:30:00 (MST-7)
Location: BEARDSLEY
Flood cause: Heavy Rain
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Widespread moderate to heavy showers developed across the northwest portion of the greater Phoenix metropolitan area during the morning and early afternoon hours on October 13th. Some of the heavy showers impacted communities such as Beardsley and Surprise. Peak rain rates were in excess of one inch per hour, sufficient to cause episodes of flash flooding. According to the City of Surprise Police Department, flash flooding resulted in the closure of Dale Lane where it intersects 163rd Avenue. The flooding was about 5 miles northwest of Beardsley and southeast of Wittmann. A Flash Flood Warning was in effect at the time of the flooding; no reports of accidents or injuries were received.

Flash Flood in MARICOPA, ARIZONA
From 13-OCT-18 13:00:00 to 13-OCT-18 14:45:00 (MST-7)
Location: PARADISE VLY
Flood cause: Heavy Rain
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Widespread moderate to heavy showers developed across the central portions of the greater Phoenix metropolitan area during the morning hours on October 13th, and they continued into the afternoon hours. The heavy showers impacted communities such as Scottsdale. Peak rain rates were in excess of one inch per hour and this resulted in episodes of flash flooding. According to local law enforcement, at 1400MST flash flooding resulted in the closure of Oak Street at 77th Street. The flooding occurred about 2 miles southeast of Scottsdale. A Flash Flood Warning was in effect at the time of the flooding and no accidents were reported due to the flooded roads and hazardous driving conditions.

Flash Flood in MARICOPA, ARIZONA
From 13-OCT-18 11:00:00 to 13-OCT-18 14:00:00 (MST-7)
Location: PERRYVILLE
Flood cause: Heavy Rain
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Widespread moderate to heavy showers developed across the western portions of the greater Phoenix metropolitan area during the morning and early afternoon hours on October 13th. Some of the heavy showers affected the areas around the community of Goodyear. Peak rain rates were in excess of one inch per hour and resulted in episodes of flash flooding. According to the City of Goodyear Emergency Manager, at 1234MST flash flooding resulted in the closure of Citrus Road between McDowell Road and Van Buren Road. The road was closed in both directions due to the flooding. The flooding occurred just west of the intersection of the Loop 303 highway and Interstate 10, about 2 miles northwest of Goodyear. A Flash Flood Warning was in effect at the time of the flooding; there were no reports of accidents due to the flooded roads and hazardous driving conditions.

Flash Flood in PINAL, ARIZONA
From 13-OCT-18 09:00:00 to 13-OCT-18 13:00:00 (MST-7)
Location: APACHE JCT
Flood cause: Heavy Rain
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Department of Highways

Widespread moderate to heavy showers developed across the eastern portion of the greater Phoenix metropolitan area during the morning hours on October 13th. Some of the heavier showers affected communities such as Apache Junction; peak rain rates were in excess of one inch per hour and led to episodes of flash flooding, including the rapid flooding of washes such as the Palm Wash. According to a report from the Arizona Department of Highways, at 1000MST 16th Avenue between Ironwood Drive and Saguaro Drive was closed due to flash flooding from the Palm Wash. The water depth at the crest was estimated at 2 feet. No accidents or injuries were reported due to the flash flooding.

Heavy Rain in PINAL, ARIZONA
From 13-OCT-18 09:30:00 to 13-OCT-18 12:00:00 (MST-7)
Location: CASA GRANDE
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Numerous moderate to heavy showers developed across the deserts of northwest Pinal County during the morning hours on October 13th and some of them affected the community of Casa Grande. The showers were triggered by the approach of a strong Pacific low pressure system and the heavier showers experienced peak rain rates in excess of one inch per hour. At 0955MST a report from the general public was received that indicated curb to curb street flooding was occurring in a neighborhood in the town of Casa Grande. Significant flash flooding did not occur however and no accidents were reported.

Flash Flood in MARICOPA, ARIZONA
From 13-OCT-18 12:50:00 to 13-OCT-18 16:00:00 (MST-7)
Location: PHOENIX
Flood cause: Heavy Rain
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Newspaper

Widespread moderate to heavy showers developed across the central portion of the greater Phoenix metropolitan area during the morning hours on October 13th, and the showers continued into the afternoon. The heavy showers impacted the downtown Phoenix area including the Arizona State Fair. Peak rain rates were in excess of one inch per hour and this led to episodes of flooding and flash flooding. According to a report in a local newspaper, flash flooding occurred at the state fair fairgrounds as well as area roads surrounding the fair. Due to the flooded fairgrounds and surrounding roads, the state fair was closed at 1430MST. A Flash Flood Warning was in effect at the time of the flooding. Fortunately there were no reports of accidents or injuries at the fair.

Flash Flood in MARICOPA, ARIZONA
From 13-OCT-18 11:00:00 to 13-OCT-18 14:00:00 (MST-7)
Location: COTTON CENTER
Flood cause: Heavy Rain
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Department of Highways

Widespread moderate to heavy showers developed during the morning hours across the lower deserts southwest of Phoenix on October 13th. Some of the heavier showers affected the area between Gila Bend and the town of Buckeye. Peak rain rates exceeded one inch per hour and were sufficient to cause episodes of flash flooding. According to the Maricopa County Department of Transportation, at 1300MST flash flooding caused the closure of old US Highway 80; it was closed for northbound travel at Patterson Road. The flooding occurred about midway between Gila Bend and Buckeye, and on the west side of Highway 85. No accidents were reported due to the flooding. A Flash Flood Warning was issued for the area at about 1000MST and it remained in effect through 1400MST.

Flash Flood in MARICOPA, ARIZONA
From 13-OCT-18 12:00:00 to 13-OCT-18 14:00:00 (MST-7)
Location: LIBERTY
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Widespread moderate to heavy showers developed over the western portions of the greater Phoenix metropolitan area during the morning and early afternoon hours on October 13th. Peak rain rates with the heavier showers were in excess of one inch per hour and resulted in episodes of flash flooding that affected communities such as Buckeye. According to the Maricopa County Department of Transportation, at 1311MST flash flooding resulted in the closure of Narramore Road to the west of Airport Road. This was approximately 6 miles to the southeast of Buckeye. A Flash Flood Warning was in effect at the time of the flooding. There were no accidents reported due to the flooded roads and hazardous driving conditions.

Flash Flood in MARICOPA, ARIZONA
From 13-OCT-18 12:00:00 to 13-OCT-18 14:30:00 (MST-7)
Location: WEST CHANDLER
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Widespread moderate to heavy showers developed over the central portion of the greater Phoenix area during the morning hours on October 13th; the showers persisted into the afternoon hours and affected communities such as Ahwatukee and Guadalupe. Peak rain rates were in excess of one inch per hour and resulted in episodes of flash flooding. According to the Phoenix Police Department, flash flooding resulted in the closure of south 48th Street from East Warner Road to East Hoh Way. The flooding was located roughly 3 miles southwest of the town of Guadalupe. A Flash Flood Warning was in effect at the time of the flooding. No accidents were reported due to the flooded roads and the hazardous driving conditions.

Flash Flood in MARICOPA, ARIZONA
From 13-OCT-18 11:00:00 to 13-OCT-18 14:00:00 (MST-7)
Location: WADDELL
Flood cause: Heavy Rain
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Widespread moderate to heavy showers developed across the west and northwest portions of the greater Phoenix metropolitan area during the morning and early afternoon hours on October 13th. The showers affected communities such as Surprise and Beardsley. Peak rain rates were in excess of one inch per hour and resulted in episodes of flash flooding. According to the City of Surprise Emergency Manager, at 1230MST flash flooding 8 miles west of Beardsley resulted in the closure of 219th Avenue north of Sun Valley Parkway. The flooding was north of the White Tank Mountains and west of Surprise and the Loop 303 highway. A Flash Flood Warning was in effect at the time of the flooding and there were no reports of accidents.

Flash Flood in MARICOPA, ARIZONA
From 13-OCT-18 11:00:00 to 13-OCT-18 14:00:00 (MST-7)
Location: VALENCIA
Flood cause: Heavy Rain
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Widespread moderate to heavy showers developed across the western portion of the greater Phoenix metropolitan area during the morning and early afternoon hours on October 13th. The heavy showers affected the area around the town of Buckeye. Peak rain rates were in excess of one inch per hour and resulted in episodes of flash flooding. According to the Buckeye Police Department, at 1210MST flash flooding resulted in the closure of Miller Road and Lower Buckeye Road, about 3 miles to the north of Buckeye. A Flash Flood Warning was in effect at the time of the flooding but there were no reports of accidents due to the flooded roads and hazardous driving conditions.

Flash Flood in MARICOPA, ARIZONA
From 13-OCT-18 14:50:00 to 13-OCT-18 16:45:00 (MST-7)
Location: SMURR
Flood cause: Heavy Rain
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Mesonet

Widespread moderate to heavy showers developed across the southwest portion of Maricopa County during the morning and early afternoon hours on October 13th. Some of the heavy showers resulted in significant flow down area washes such as the Sand Tank Wash north of Gila Bend. Peak rain rates were in excess of one inch per hour and resulted in episodes of flash flooding just to the north of the town of Gila Bend. According to mesonet data, which included stream gauge data from the Maricopa County Flood Control District, flash flooding down the Sand Tank Wash resulted in the closure of Watermelon Road and Indian Road at about 1500MST. A Flash Flood Warning was issued shortly before the flooding, at 1450MST, and it remained in effect through 1645MST. No accidents or injuries were reported due to the flash flooding.

Flash Flood in PINAL, ARIZONA
From 13-OCT-18 09:15:00 to 13-OCT-18 13:15:00 (MST-7)
Location: LIRIM
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Widespread moderate to heavy showers developed south of Phoenix during the morning hours on October 13th, affecting areas around the town of Maricopa. Peak rain rates were in excess of one inch per hour and led to episodes of flash flooding. At 0939MST the City of Maricopa Emergency Manager reported that flood gates were closed in Rancho El Dorado and flash flooding was occurring near the intersection of Porter Road and Farrell Road. The flooding was occurring about 3 miles southeast of the town of Maricopa. A Flash Flood Warning was in effect at the time of the flooding; it was issued at 0914MST and remained in effect until 1315MST. No accidents were reported.