A similar pattern existed on the 31st compared to the previous day with an upper level low in the eastern Pacific near the west coast of the Baja Peninsula promoting diffluent flow across southeast California. Better moisture existed on this day compared to the previous day, leading to a more enhanced flash flooding event. The most intense rainfall occurred in northeast Imperial County along SR 78, where nearly 7 inches of rain was estimated to have fallen within a 5 hour period. An unbridged crossing along SR 78 at Milpitas Wash became flooded with swiftly flowing water due to the heavy rainfall. A vehicle attempting to cross through the flooded portion of the highway was swept off the roadway before overturning in the wash. Both of the occupants perished in the flash flood. Strong to severe thunderstorms across the Imperial Valley led to damaging wind gusts that resulted in numerous downed power poles. According to the Imperial Irrigation District, extensive damage sustained to the power infrastructure on both the 30th and 31st would cost the district more than $8 million.

Thunderstorm Wind in IMPERIAL, CALIFORNIA
From 31-AUG-21 15:53:00 to 31-AUG-21 15:53:00 (PST-8)
Location: WIEST
Magnitude: 50.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Law Enforcement

A power pole was reported down and blocking traffic near Rutherford Road and West Road. No injuries were reported. Timing was estimated using radar.

Thunderstorm Wind in IMPERIAL, CALIFORNIA
From 31-AUG-21 16:26:00 to 31-AUG-21 16:26:00 (PST-8)
Location: CALIPATRIA
Magnitude: 55.00 EG
Property damage: 1.00M
Crop damage: 0.00K
Reported by: Newspaper

An article from a local newspaper reported numerous transmission and distribution power poles were down in an area between Calipatria and Niland due to damaging wind gusts. According to the Imperial Irrigation District, over 100 power poles were knocked down by the storm. Photos shared on social media showed multiple power poles down along Lindsey Road and Gentry Road. No injuries were reported. Timing was estimated using radar.

Thunderstorm Wind in IMPERIAL, CALIFORNIA
From 31-AUG-21 17:30:00 to 31-AUG-21 17:30:00 (PST-8)
Location: EL CENTRO NAF
Magnitude: 50.00 EG
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Power lines down along with approximately 20 power poles down or leaning over were reported along Evan Hewes Highway near Forrester Road. No injuries were reported. Timing was estimated using radar.

Flash Flood in IMPERIAL, CALIFORNIA
From 31-AUG-21 17:54:00 to 31-AUG-21 18:54:00 (PST-8)
Location: SALTON CITY
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

The California Highway Patrol reported water and debris across SR 86 at Willow Wash, making the road impassable. No injuries were reported.

Flash Flood in IMPERIAL, CALIFORNIA
From 31-AUG-21 20:25:00 to 31-AUG-21 21:25:00 (PST-8)
Location: CALEXICO INTL ARPT
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

The California Highway Patrol reported that Cole Boulevard at Dogwood Road was closed due to flooding. No injuries were reported.

Flash Flood in IMPERIAL, CALIFORNIA
From 31-AUG-21 12:59:00 to 31-AUG-21 18:00:00 (PST-8)
Location: PALO VERDE
Flood cause: Heavy Rain
Property damage: 1.00M
Crop damage: 0.00K
Reported by: Department of Highways

Thunderstorms produced very heavy rainfall across northeast portions of Imperial County where nearly 7 inches of rain was estimated to have fallen in a 5 hour period. The Cibola RAWS site recorded 1.58 inches of rain between 1348PDT and 1548PDT. As a result, extensive flooding occurred along SR 78 from Palo Verde and areas south, damaging the road and leading to an extended closure for repairs.

Flash Flood in IMPERIAL, CALIFORNIA
From 31-AUG-21 13:47:00 to 31-AUG-21 18:00:00 (PST-8)
Location: PALO VERDE
Flood cause: Heavy Rain
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Very heavy rainfall occurred along SR 78 in northeast Imperial County with amounts estimated to be approaching 7 inches in some places. This resulted in considerable flooding along the highway. The California Highway Patrol reported that a vehicle was swept off SR 78 at Milpitas Wash before overturning in the wash. Both occupants perished in the flash flood.