An approaching upper level low, combined with substantial surface moisture on the northern edge of a developing nocturnal low level jet, resulted in the north-northeastward development of elevated thunderstorms from eastern Montana into portions of northwest and north central North Dakota during the early morning hours of Saturday, May 29th.  Several reports of large hail were received along with one report of a severe thunderstorm wind gust. In addition, heavy rainfall also resulted in flash flooding conditions as the thunderstorms continued to develop and train over some locations.

Hail in WARD, NORTH DAKOTA
From 29-MAY-10 05:46:00 to 29-MAY-10 05:53:00 (CST-6)
Location: KENMARE
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Hail in WILLIAMS, NORTH DAKOTA
From 29-MAY-10 02:12:00 to 29-MAY-10 02:19:00 (CST-6)
Location: WILLISTON
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Thunderstorm Wind in WILLIAMS, NORTH DAKOTA
From 29-MAY-10 02:37:00 to 29-MAY-10 02:42:00 (CST-6)
Location: TIOGA
Magnitude: 58.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in BOTTINEAU, NORTH DAKOTA
From 29-MAY-10 04:45:00 to 29-MAY-10 04:55:00 (CST-6)
Location: BOTTINEAU
Magnitude: 61.00 EG
Property damage: 75.00K
Crop damage: 0.00K
Reported by: Newspaper

Strong thunderstorm winds resulted in damage on the west side of Bottineau. Several grain bins were knocked over, one transmission tower was knocked down, and several trees sustained damage.

Hail in DIVIDE, NORTH DAKOTA
From 29-MAY-10 03:35:00 to 29-MAY-10 03:40:00 (CST-6)
Location: AMBROSE
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in WARD, NORTH DAKOTA
From 29-MAY-10 03:47:00 to 29-MAY-10 03:53:00 (CST-6)
Location: BERTHOLD
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Hail in WARD, NORTH DAKOTA
From 29-MAY-10 03:49:00 to 29-MAY-10 03:55:00 (CST-6)
Location: BERTHOLD
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Thunderstorm Wind in MOUNTRAIL, NORTH DAKOTA
From 29-MAY-10 05:30:00 to 29-MAY-10 05:32:00 (CST-6)
Location: BLAISDELL
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

The report indicated that no damage was done.

Thunderstorm Wind in BURKE, NORTH DAKOTA
From 29-MAY-10 03:10:00 to 29-MAY-10 03:15:00 (CST-6)
Location: COLUMBUS
Magnitude: 65.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Public

The high thunderstorm wind damaged oil tanks. The tanks were overturned. The time and wind speed are both estimated.

Flash Flood in WILLIAMS, NORTH DAKOTA
From 29-MAY-10 02:31:00 to 29-MAY-10 03:31:00 (CST-6)
Location: GRENORA
Flood cause: Heavy Rain
Property damage: 45.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Several culverts were washed out along with flooding at an oil drilling site.

Flash Flood in WILLIAMS, NORTH DAKOTA
From 29-MAY-10 03:00:00 to 29-MAY-10 04:00:00 (CST-6)
Location: ALAMO
Flood cause: Heavy Rain
Property damage: 20.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Public reports of flash flooding were received via broadcast media over rural north central Williams County. Rainfall rates were reported to be around two inches in less than 45 minutes. Some county roads were damaged by the flowing water.