Isolated monsoon thunderstorms developed across the southwestern deserts during the evening hours on September 4th and some of them affected areas to the northeast of Yuma and east of the lower Colorado River valley. The storms produced weather hazards typical of monsoon storms; gusty and damaging outflow winds and locally heavy rainfall. Heavy rains produced an episode of flash flooding; at 2022MST a mesonet gage reported a 9 foot rise in water in an unnamed wash in the Yuma Proving Ground. A bit earlier, at 1912MST, another mesnet gage in the proving ground measured a gust to 68 mph. Additionally, strong winds blew over 7 power poles and bent numerous others in the same proving grounds, about 26 miles northwest of Ligurta. No injuries were reported as a result of the strong winds.

Thunderstorm Wind in YUMA, ARIZONA
From 04-SEP-19 19:12:00 to 04-SEP-19 19:12:00 (MST-7)
Location: YUMA PROVING GROUND
Magnitude: 59.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Isolated monsoon thunderstorms developed across the west and southwest portions of Yuma County during the evening hours on September 4th. One of the stronger storms that occurred over the Yuma Proving Ground generated a very strong wind gust. At 1912MST a mesonet weather gage located 21 miles north of the town of Ligurta recorded a peak gust to 68 mph. Due to the very open terrain, no damage was reported due to the strong wind gust.

Flash Flood in YUMA, ARIZONA
From 04-SEP-19 20:08:00 to 04-SEP-19 23:00:00 (MST-7)
Location: YUMA PROVING GROUND
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Isolated monsoon thunderstorms developed across the southwest deserts, including areas to the northeast of Yuma, during the evening hours on September 4th. In addition to typical storm hazards such as gusty damaging outflow winds, some of the storm produced locally heavy rain with peak rain rates in excess of one inch per hour. The heavy rain led to an episode of flash flooding that occurred over the Yuma Proving Ground. According to a mesonet stream gage report, at 2022MST a 9 foot rise in water was recorded on an unnamed wash. The flash flood occurred about 18 miles north of the town of Ligurta. Due to the open terrain of the proving ground, no injuries or impacts were reported due to the flash flood. A Flash Flood Watch was issued about 15 minutes prior to the flash flood report.

Thunderstorm Wind in YUMA, ARIZONA
From 04-SEP-19 19:36:00 to 04-SEP-19 19:36:00 (MST-7)
Location: MARTINEZ LAKE
Magnitude: 61.00 EG
Property damage: 75.00K
Crop damage: 0.00K
Reported by: Public

Isolated thunderstorms developed across the southwest deserts, to the northeast of Yuma and to the east of the lower Colorado River valley, during the evening hours on September 4th. The stronger storms generated very powerful outflow winds; a relatively nearby mesonet gage near the Middle Mountains measured a gust to 68 mph at 1912MST. According to a report from the public, at 1936MST winds gusts estimated to be as high as 70 mph blew down 7 power poles in the Yuma Proving Grounds about 26 miles northwest of the town of Ligurta. Numerous additional poles were bent over and leaning at an angle in the proving grounds. There were no reports of injuries fortunately.