Severe thunderstorms formed the afternoon of Memorial Day.  Fourteen tornadoes were observed by spotters and chasers in the afternoon.  A rare sighting of a tornado was reported from Jackson County.  Some of the strongest storms formed across northeast Colorado, along a surface convergence boundary. The boundary extended from Kit Carson County north into Washington County, and then through Morgan and Weld counties. Intense convection that developed right on top of the boundary generated several tornadoes, with a few occurring simultaneously, especially across extreme southeast Washington County. Most of the tornadoes touched down in open fields and produced just minor crop damage. The heaviest damage occurred in Cope, in southeast Washington County, from an EF-1 tornado.  It caused extensive damage to a carport and garage on the southeast side of town, and downed some trees. The storms also produced hail up to the size of tennis balls in Washington County.  Further west, across the foothills west of Denver and across metro Denver,  instability was weaker and marginally severe hail occurred, including accumulating hail across the south metro Denver.

Tornado in WASHINGTON, COLORADO
From 28-MAY-18 16:15:00 to 28-MAY-18 16:37:00 (MST-7)
Location: ARICKAREE
Tornado F-scale: EF0
Property damage: 0.00K
Reported by: Trained Spotter

This is the second of three tornadoes  that touched down simultaneously in close proximity to one another.  No damage was reported and the storm eventually crossed into Kit Carson County.

Hail in ADAMS, COLORADO
From 28-MAY-18 15:37:00 to 28-MAY-18 15:37:00 (MST-7)
Location: AURORA
Magnitude: 0.88 
Reported by: Trained Spotter

Tornado in WASHINGTON, COLORADO
From 28-MAY-18 16:42:00 to 28-MAY-18 16:45:00 (MST-7)
Location: COPE
Tornado F-scale: EF1
Reported by: Emergency Manager

A tornado touched down and caused extensive damage to a carport and garage.  One pine tree was uprooted.

Tornado in JACKSON, COLORADO
From 28-MAY-18 12:15:00 to 28-MAY-18 12:25:00 (MST-7)
Location: RAND
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A tornado touched down in open country for several minutes.  No damage was observed.

Hail in DOUGLAS, COLORADO
From 28-MAY-18 15:37:00 to 28-MAY-18 15:37:00 (MST-7)
Location: HIGHLANDS RANCH
Magnitude: 1.00 
Reported by: Trained Spotter

Tornado in WASHINGTON, COLORADO
From 28-MAY-18 15:22:00 to 28-MAY-18 15:30:00 (MST-7)
Location: ARICKAREE
Tornado F-scale: EF0
Property damage: 0.00K
Reported by: Trained Spotter

A tornado touched down in a corn field.  It was on the ground for several minutes and likely produced crop damage.

Tornado in WASHINGTON, COLORADO
From 28-MAY-18 16:00:00 to 28-MAY-18 16:07:00 (MST-7)
Location: ARICKAREE
Tornado F-scale: EF0
Property damage: 0.00K
Reported by: Trained Spotter

A tornado touched down in an open field and likely produced some crop damage.  Another tornado touched down in close proximity to this one.

Hail in CLEAR CREEK, COLORADO
From 28-MAY-18 13:46:00 to 28-MAY-18 13:46:00 (MST-7)
Location: IDAHO SPGS
Magnitude: 1.00 
Reported by: Trained Spotter

Hail in WASHINGTON, COLORADO
From 28-MAY-18 15:47:00 to 28-MAY-18 15:47:00 (MST-7)
Location: ARICKAREE
Magnitude: 1.75 
Reported by: Storm Chaser

Hail in JEFFERSON, COLORADO
From 28-MAY-18 13:58:00 to 28-MAY-18 13:58:00 (MST-7)
Location: EVERGREEN
Magnitude: 1.25 
Reported by: Trained Spotter

Hail in JEFFERSON, COLORADO
From 28-MAY-18 13:53:00 to 28-MAY-18 13:53:00 (MST-7)
Location: EVERGREEN
Magnitude: 1.00 
Reported by: Public

Hail in ARAPAHOE, COLORADO
From 28-MAY-18 15:56:00 to 28-MAY-18 15:56:00 (MST-7)
Location: CENTENNIAL AIRPORT
Magnitude: 1.00 
Reported by: Broadcast Media

Hail in WASHINGTON, COLORADO
From 28-MAY-18 16:40:00 to 28-MAY-18 16:40:00 (MST-7)
Location: COPE
Magnitude: 2.50 
Reported by: Trained Spotter

Tornado in WASHINGTON, COLORADO
From 28-MAY-18 16:00:00 to 28-MAY-18 16:03:00 (MST-7)
Location: ARICKAREE
Tornado F-scale: EF0
Property damage: 0.00K
Reported by: Trained Spotter

A tornado touched down in a corn field.  Some crop damage was likely.

Tornado in MORGAN, COLORADO
From 28-MAY-18 16:10:00 to 28-MAY-18 16:15:00 (MST-7)
Location: GOODRICH
Tornado F-scale: EF0
Reported by: Trained Spotter

A tornado touched down briefly and produced minor crop damage.

Hail in JEFFERSON, COLORADO
From 28-MAY-18 15:20:00 to 28-MAY-18 15:20:00 (MST-7)
Location: MORRISON
Magnitude: 1.00 
Reported by: Trained Spotter

Hail in WASHINGTON, COLORADO
From 28-MAY-18 15:25:00 to 28-MAY-18 15:25:00 (MST-7)
Location: ARICKAREE
Magnitude: 1.75 
Reported by: Trained Spotter

Hail in JEFFERSON, COLORADO
From 28-MAY-18 15:29:00 to 28-MAY-18 15:29:00 (MST-7)
Location: LAKEWOOD
Magnitude: 1.00 
Reported by: Trained Spotter

Tornado in MORGAN, COLORADO
From 28-MAY-18 17:32:00 to 28-MAY-18 17:37:00 (MST-7)
Location: FT MORGAN ARPT
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

A tornado touched down briefly in an open field.  No damage was observed.

Thunderstorm Wind in WELD, COLORADO
From 28-MAY-18 16:17:00 to 28-MAY-18 16:17:00 (MST-7)
Location: LUCERNE
Magnitude: 50.00 EG
Property damage: 0.00K
Reported by: Amateur Radio

Strong thunderstorm winds caused minor tree damage.

Tornado in WASHINGTON, COLORADO
From 28-MAY-18 16:11:00 to 28-MAY-18 16:27:00 (MST-7)
Location: COPE
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

One of three landspouts that formed in an open field in close proximity to one another.
No damage was observed.

Tornado in WASHINGTON, COLORADO
From 28-MAY-18 16:29:00 to 28-MAY-18 16:32:00 (MST-7)
Location: ARICKAREE
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

This was the third of three tornadoes that was visible simultaneously across rural Washington County.  It touched down in an open field with no damage reported.

Tornado in WELD, COLORADO
From 28-MAY-18 16:34:00 to 28-MAY-18 16:35:00 (MST-7)
Location: GROVER
Tornado F-scale: EF0
Crop damage: 0.00K
Reported by: Trained Spotter

A tornado touched down briefly.  Some power lines were damaged in the vicinity of the touchdown.

Tornado in WASHINGTON, COLORADO
From 28-MAY-18 16:23:00 to 28-MAY-18 16:39:00 (MST-7)
Location: COPE
Tornado F-scale: EF0
Property damage: 0.00K
Reported by: Trained Spotter

The last in a series of three landspouts touched down in close proximity to one another.
It touched down in an open corn field and likely produced some crop damage.

Tornado in WELD, COLORADO
From 28-MAY-18 16:37:00 to 28-MAY-18 16:38:00 (MST-7)
Location: BUCKINGHAM
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A tornado touched down briefly in an open field.  No damage was observed.

Tornado in MORGAN, COLORADO
From 28-MAY-18 17:24:00 to 28-MAY-18 17:29:00 (MST-7)
Location: GOODRICH
Tornado F-scale: EF0
Reported by: Trained Spotter

A tornado touched down briefly near County Road U and lifted near County Road 9.  Minor crop and property damage were observed.