The seasons first severe weather outbreak occurred during the afternoon and evening hours of the 18th. A cluster of thunderstorms developed across Sweet Grass and Stillwater Counties during the early afternoon hours as an upper level impulse approached the area. As the line moved east into a more favorable buoyancy/shear environment, (MLCAPE combined with 500 to 1500J/KG along with effective shears of 55 to 60kts) the thunderstorms quickly intensified, especially over the Billings area.
Three large feeder-lines went down leaving 2,600 customers in Laurel and the West End of Billings without power for about an hour. In addition, the large hail, some of which was the size of walnuts and a few tennis ball size, resulted in considerable damage to homes and cars across the immediate Billings area.
As for area crops, the hail mowed a 3,000 acre patch across sugar beet farms from Billings to Hardin. Winter wheat, 64 percent of which had been rated good to excellent, took a beating, as did malt barley. Sugar beets seemed to get the worst of the damage. The heaviest damage was found north of Hardin, west of Billings and north of Worden/Shepherd.

Thunderstorm Wind in YELLOWSTONE, MONTANA
From 18-MAY-14 17:00:00 to 18-MAY-14 17:00:00 (MST-7)
Location: BALLANTINE
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A wind gust of 60 mph was estimated just west of Ballantine.

Hail in BIG HORN, MONTANA
From 18-MAY-14 17:02:00 to 18-MAY-14 17:02:00 (MST-7)
Location: HARDIN
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in YELLOWSTONE, MONTANA
From 18-MAY-14 15:55:00 to 18-MAY-14 15:55:00 (MST-7)
Location: LAUREL
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in YELLOWSTONE, MONTANA
From 18-MAY-14 16:09:00 to 18-MAY-14 16:09:00 (MST-7)
Location: (BIL)LOGAN ARPT BILL
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in YELLOWSTONE, MONTANA
From 18-MAY-14 16:00:00 to 18-MAY-14 16:00:00 (MST-7)
Location: RIMROCK
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

Thunderstorm Wind in YELLOWSTONE, MONTANA
From 18-MAY-14 16:09:00 to 18-MAY-14 16:09:00 (MST-7)
Location: (BIL)LOGAN ARPT BILL
Magnitude: 59.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Winds were sustained at 52 mph for a few minutes with peak gusts to 59 mph.

Hail in BIG HORN, MONTANA
From 18-MAY-14 17:14:00 to 18-MAY-14 17:14:00 (MST-7)
Location: GARRYOWEN
Magnitude: 2.50 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in BIG HORN, MONTANA
From 18-MAY-14 17:30:00 to 18-MAY-14 17:30:00 (MST-7)
Location: HARDIN
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

Hail in YELLOWSTONE, MONTANA
From 18-MAY-14 16:10:00 to 18-MAY-14 16:10:00 (MST-7)
Location: BILLINGS HGTS
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

Hail in YELLOWSTONE, MONTANA
From 18-MAY-14 16:11:00 to 18-MAY-14 16:11:00 (MST-7)
Location: BILLINGS
Magnitude: 2.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

Hail in ROSEBUD, MONTANA
From 18-MAY-14 18:05:00 to 18-MAY-14 18:05:00 (MST-7)
Location: COLSTRIP
Magnitude: 2.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in YELLOWSTONE, MONTANA
From 18-MAY-14 16:12:00 to 18-MAY-14 16:12:00 (MST-7)
Location: (BIL)LOGAN ARPT BILL
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in YELLOWSTONE, MONTANA
From 18-MAY-14 16:12:00 to 18-MAY-14 16:12:00 (MST-7)
Location: BILLINGS
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

Hail in ROSEBUD, MONTANA
From 18-MAY-14 17:55:00 to 18-MAY-14 17:55:00 (MST-7)
Location: LAME DEER
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: County Official

Thunderstorm Wind in BIG HORN, MONTANA
From 18-MAY-14 17:59:00 to 18-MAY-14 17:59:00 (MST-7)
Location: CROW AGENCY
Magnitude: 53.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Hail in ROSEBUD, MONTANA
From 18-MAY-14 18:20:00 to 18-MAY-14 18:20:00 (MST-7)
Location: LAME DEER
Magnitude: 2.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

Hen egg size hail did damage to cars and car windshields on Birney Divide.

Hail in YELLOWSTONE, MONTANA
From 18-MAY-14 16:15:00 to 18-MAY-14 16:15:00 (MST-7)
Location: (BIL)LOGAN ARPT BILL
Magnitude: 1.50 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

Thunderstorm Wind in YELLOWSTONE, MONTANA
From 18-MAY-14 16:16:00 to 18-MAY-14 16:16:00 (MST-7)
Location: (BIL)LOGAN ARPT BILL
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

A wind gust of 60 mph was estimated just northwest of Billings.

Hail in ROSEBUD, MONTANA
From 18-MAY-14 18:20:00 to 18-MAY-14 18:20:00 (MST-7)
Location: ASHLAND
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in ROSEBUD, MONTANA
From 18-MAY-14 18:33:00 to 18-MAY-14 18:33:00 (MST-7)
Location: ASHLAND
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in PARK, MONTANA
From 18-MAY-14 14:00:00 to 18-MAY-14 14:00:00 (MST-7)
Location: LIVINGSTON
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in SWEET GRASS, MONTANA
From 18-MAY-14 14:05:00 to 18-MAY-14 14:05:00 (MST-7)
Location: BIG TIMBER
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

Hail in YELLOWSTONE, MONTANA
From 18-MAY-14 16:19:00 to 18-MAY-14 16:19:00 (MST-7)
Location: BILLINGS
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in YELLOWSTONE, MONTANA
From 18-MAY-14 16:25:00 to 18-MAY-14 16:25:00 (MST-7)
Location: LOCKWOOD
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

The hail broke a basement window.

Thunderstorm Wind in POWDER RIVER, MONTANA
From 18-MAY-14 19:16:00 to 18-MAY-14 19:16:00 (MST-7)
Location: BROADUS
Magnitude: 61.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A wind gust of 70 mph was estimated just west/northwest of Broadus.

Hail in POWDER RIVER, MONTANA
From 18-MAY-14 19:30:00 to 18-MAY-14 19:30:00 (MST-7)
Location: OLIVE
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Funnel Cloud in PARK, MONTANA
From 18-MAY-14 14:21:00 to 18-MAY-14 14:21:00 (MST-7)
Location: SPRINGDALE
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Hail in YELLOWSTONE, MONTANA
From 18-MAY-14 16:20:00 to 18-MAY-14 16:20:00 (MST-7)
Location: HUNTLEY
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in BIG HORN, MONTANA
From 18-MAY-14 16:58:00 to 18-MAY-14 16:58:00 (MST-7)
Location: HARDIN
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in STILLWATER, MONTANA
From 18-MAY-14 14:50:00 to 18-MAY-14 14:50:00 (MST-7)
Location: REED PT
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Tornado in POWDER RIVER, MONTANA
From 18-MAY-14 16:50:00 to 18-MAY-14 17:00:00 (MST-7)
Location: BELLE CREEK ARPT
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Brief tornado in open field with no damage reported.

Funnel Cloud in POWDER RIVER, MONTANA
From 18-MAY-14 16:38:00 to 18-MAY-14 16:38:00 (MST-7)
Location: BELLE CREEK ARPT
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in BIG HORN, MONTANA
From 18-MAY-14 17:00:00 to 18-MAY-14 17:00:00 (MST-7)
Location: HARDIN
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: County Official

Hail in YELLOWSTONE, MONTANA
From 18-MAY-14 16:20:00 to 18-MAY-14 16:20:00 (MST-7)
Location: MOSSMAIN
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in STILLWATER, MONTANA
From 18-MAY-14 14:52:00 to 18-MAY-14 14:52:00 (MST-7)
Location: REED PT
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Hail in STILLWATER, MONTANA
From 18-MAY-14 14:52:00 to 18-MAY-14 14:52:00 (MST-7)
Location: REED PT
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in YELLOWSTONE, MONTANA
From 18-MAY-14 16:17:00 to 18-MAY-14 16:17:00 (MST-7)
Location: BILLINGS HGTS
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in BIG HORN, MONTANA
From 18-MAY-14 17:08:00 to 18-MAY-14 17:08:00 (MST-7)
Location: HARDIN
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in YELLOWSTONE, MONTANA
From 18-MAY-14 16:36:00 to 18-MAY-14 16:36:00 (MST-7)
Location: SHEPHERD
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in YELLOWSTONE, MONTANA
From 18-MAY-14 16:09:00 to 18-MAY-14 16:09:00 (MST-7)
Location: BILLINGS
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

Hail in YELLOWSTONE, MONTANA
From 18-MAY-14 16:16:00 to 18-MAY-14 16:16:00 (MST-7)
Location: (BIL)LOGAN ARPT BILL
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in SWEET GRASS, MONTANA
From 18-MAY-14 14:27:00 to 18-MAY-14 14:27:00 (MST-7)
Location: BIG TIMBER
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in YELLOWSTONE, MONTANA
From 18-MAY-14 15:46:00 to 18-MAY-14 15:46:00 (MST-7)
Location: HESPER
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in YELLOWSTONE, MONTANA
From 18-MAY-14 15:55:00 to 18-MAY-14 15:55:00 (MST-7)
Location: YEGEN
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

Hail in SWEET GRASS, MONTANA
From 18-MAY-14 14:27:00 to 18-MAY-14 14:27:00 (MST-7)
Location: PRYOR
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter