An upper air disturbance moves east just north of a frontal boundary that helped to trigger severe weather. The severe weather that included one of the strongest tornadoes in Montana history started in far southern Saskatchewan and moved southeast across the area.

Hail in DANIELS, MONTANA
From 26-JUL-10 16:50:00 to 26-JUL-10 16:50:00 (MST-7)
Location: RICHLAND
Magnitude: 1.75 
Property damage: 0.00K
Reported by: Trained Spotter

Crop damage was reported with the 1.75 hail.

Hail in DANIELS, MONTANA
From 26-JUL-10 17:00:00 to 26-JUL-10 17:00:00 (MST-7)
Location: PEERLESS
Magnitude: 1.75 
Property damage: 0.00K
Reported by: Trained Spotter

Some crop damage noted with golfball size hail.

Hail in DANIELS, MONTANA
From 26-JUL-10 16:30:00 to 26-JUL-10 16:30:00 (MST-7)
Location: PEERLESS
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Rotating wall cloud also reported.

Hail in DANIELS, MONTANA
From 26-JUL-10 17:00:00 to 26-JUL-10 17:00:00 (MST-7)
Location: SCOBEY
Magnitude: 4.00 
Reported by: Public

Very large hail of 3 to 4 inches were reported by the public.

Hail in DANIELS, MONTANA
From 26-JUL-10 16:55:00 to 26-JUL-10 16:55:00 (MST-7)
Location: PEERLESS
Magnitude: 1.75 
Reported by: Public

Public report of golfball size hail.

Hail in SHERIDAN, MONTANA
From 26-JUL-10 19:00:00 to 26-JUL-10 19:00:00 (MST-7)
Location: MEDICINE LAKE
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Quarter size hail was observed with a 70 mph wind.

Hail in SHERIDAN, MONTANA
From 26-JUL-10 19:00:00 to 26-JUL-10 19:00:00 (MST-7)
Location: RESERVE
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Penny size hail was accompanied by heavy rain.

Hail in DANIELS, MONTANA
From 26-JUL-10 17:40:00 to 26-JUL-10 17:40:00 (MST-7)
Location: FLAXVILLE
Magnitude: 2.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail of golf-ball to hen egg size was reported.

Funnel Cloud in DANIELS, MONTANA
From 26-JUL-10 17:50:00 to 26-JUL-10 17:50:00 (MST-7)
Location: FLAXVILLE
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Spotter witnessed a rotating wall cloud that produced a funnel cloud.

Funnel Cloud in DANIELS, MONTANA
From 26-JUL-10 17:00:00 to 26-JUL-10 17:05:00 (MST-7)
Location: PEERLESS
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

A wall cloud had several fingers of scud in the area.  The report was never officially confirmed by law enforcement or photographs of the cloud, but given the intense rotation of the storm, a brief funnel cloud could have been possible.

Hail in DANIELS, MONTANA
From 26-JUL-10 17:47:00 to 26-JUL-10 17:55:00 (MST-7)
Location: NAVAJO
Magnitude: 3.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Large hail covered the ground.  A lot of crop damage reported in the area.

Tornado in SHERIDAN, MONTANA
From 26-JUL-10 18:00:00 to 26-JUL-10 18:37:00 (MST-7)
Location: REDSTONE HILL DOT
Tornado F-scale: EF3
Property damage: 300.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

This was the deadliest tornado in Montana since 1923, and only the fourth EF-3 on record. The supercell thunderstorm developed strong rotation, and rotating wall clouds and brief funnel clouds were reported in Daniels County.  As the storm moved southeast, it intensified and a large, long-lived tornado formed.  The tornado traveled for 18 miles, mostly through rural areas, but it had devastating impacts as it hit a ranch, killing two people and injuring one.   On the morning of July 27th, 2010 two teams of NWS Glasgow staff surveyed the damage area.  The first team started in Daniels County and followed the track of the storm to the east-southeast.   The second team met with county and state officials at the site of the ranch that was most devastated.   Both teams spoke to law enforcement officials, as well as weather spotters and the public who had reports of weather and/or damage as well as those who saw the tornado.
The initial damage from the tornado originated about 12 miles south of Redstone.   Along the Reserve and Wanso Roads, six miles of power lines were snapped off.  Sheridan Electric was able to restore power fairly quickly to the majority of residences by the next morning.  Due to the poles being snapped, the tornado was rated an EF2 on the Enhanced Fujita Scale in this area.   This was the widest portion of the tornado track with a width of a half mile.
The tornado continued east-southeast where it encountered an abandoned farmhouse, a barn and a bridge that went across Wolf Creek on the Three Corners Road.  The bridge had the planks ripped off with damage totals coming to $100,000.  The farmhouse was blown off of the foundation, had some of the siding stripped off, and roof damage.  The barn was completely destroyed, with the west and north facing walls blown away, and the south and east facing walls intact for the most part, but flattened on the ground.  Two grain bins were destroyed, with a third still on its foundation but crushed.  They appeared to be empty.   The damage at this location was rated an EF2 on the Enhanced Fujita Scale.  The width of the tornado at this point was a quarter mile wide.
The storm continued on its east-southeast track at a speed of about 30 mph.  The Smith Ranch was then impacted.  The ranch sits on a bit of a hill with a small stream valley from the west-northwest to just north of the property.  There are no shelter belts or terrain to block some of the winds from the tornado.  The two fatalities and one injury occurred at the Smith Ranch.  The adult fatality was trying to get into the basement.  The child fatality was in the basement and the chimney collapsed and crushed him.  The adult injury was with the child, but on the other side of the chimney in the basement.
The tornado was rated an EF3 at the Smith Ranch, with a width of three tenths of a mile.  This was the highest rating during the life cycle of the tornado.  Along with the devastating destruction of property, there was also up to 40 cows and calves significantly injured or killed by the tornado and/or debris.  Many had severe injuries and had to be put down by a veterinarian.
The damage totals are estimated.
A formal written report is available from the NWS Glasgow office.

Thunderstorm Wind in SHERIDAN, MONTANA
From 26-JUL-10 19:00:00 to 26-JUL-10 19:00:00 (MST-7)
Location: MEDICINE LAKE
Magnitude: 61.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Very strong winds accompanied the storm.  NWS damage survey found evidence of wind blown debris in the Medicine Lake area.