Southern Minnesota had quite the day with record heat and afternoon and early evening thunderstorms. First, several areas across southern Minnesota, including the Twin Cities International Airport, reported record high temperatures for Memorial Day. 100 Degrees was the highest and earliest recorded 100 degree temperature at the Twin Cities airport since records were started over 150 years ago. Other areas reported 100 degrees in southern Minnesota, including Mankato.
The heat and humidity was the source of an unstable atmosphere across Minnesota. An earlier outflow boundary from thunderstorms in Wisconsin, moved westward and ignited a broken line of thunderstorms in northern Iowa, and southern Minnesota, south of Mankato, prior to 2 pm. These storms produced an outflow boundary and raced northward toward the Twin Cities metro area. Thunderstorms continued to form along the outflow boundary and a few caused severe hail, and damaging wind gusts. The largest hail stone was reported near Avon, where 2 inch diameter hail was observed and recorded on video. Elsewhere, thunderstorms that moved across the northern metro area, developed an intense downburst wind, and caused an area of large trees that were blown down between Blaine, Ham Lake, Columbus, and Lino Lakes.

Hail in SCOTT, MINNESOTA
From 28-MAY-18 14:35:00 to 28-MAY-18 14:35:00 (CST-6)
Location: ST BENEDICT
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in SCOTT, MINNESOTA
From 28-MAY-18 15:00:00 to 28-MAY-18 15:03:00 (CST-6)
Location: MARYSTOWN
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Most of the observed hail was nickel size and was reported at 150th, and Marystown Road, south of Shakopee.

Hail in SCOTT, MINNESOTA
From 28-MAY-18 15:05:00 to 28-MAY-18 15:05:00 (CST-6)
Location: MARYSTOWN
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in ANOKA, MINNESOTA
From 28-MAY-18 16:17:00 to 28-MAY-18 16:17:00 (CST-6)
Location: CIRCLE PINES
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in ANOKA, MINNESOTA
From 28-MAY-18 16:25:00 to 28-MAY-18 16:25:00 (CST-6)
Location: LINO LAKES
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in ANOKA, MINNESOTA
From 28-MAY-18 16:40:00 to 28-MAY-18 16:40:00 (CST-6)
Location: BLAINE
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in MILLE LACS, MINNESOTA
From 28-MAY-18 17:39:00 to 28-MAY-18 17:39:00 (CST-6)
Location: PEASE
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in ANOKA, MINNESOTA
From 28-MAY-18 16:35:00 to 28-MAY-18 16:37:00 (CST-6)
Location: BLAINE
Magnitude: 61.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A severe down burst wind caused numerous large trees, up to 70 inches in diameter, to blow down near the intersection of 125th Ave NE, and Radisson Road NE. This is where the large tree fell on an outhouse at the Pioneer Park. Several power poles and lines were knock down, causing sporadic power outages across the northeast part of the metro area.

Thunderstorm Wind in ANOKA, MINNESOTA
From 28-MAY-18 16:37:00 to 28-MAY-18 16:39:00 (CST-6)
Location: BLAINE
Magnitude: 56.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A severe down burst wind caused several large trees to blow down near the intersection of 128th Ave NE, and Harper Street. Several power poles and lines were knock down, causing sporadic power outages across the northeast part of the metro area.

Thunderstorm Wind in SCOTT, MINNESOTA
From 28-MAY-18 15:10:00 to 28-MAY-18 15:10:00 (CST-6)
Location: SHAKOPEE
Magnitude: 52.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in HENNEPIN, MINNESOTA
From 28-MAY-18 16:40:00 to 28-MAY-18 16:40:00 (CST-6)
Location: MSP INTL ARPT
Magnitude: 54.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Hail in MILLE LACS, MINNESOTA
From 28-MAY-18 17:45:00 to 28-MAY-18 17:45:00 (CST-6)
Location: PEASE
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in STEARNS, MINNESOTA
From 28-MAY-18 18:00:00 to 28-MAY-18 18:04:00 (CST-6)
Location: AVON
Magnitude: 2.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A swath of large hail was observed from southwest, to northwest of Avon, Minnesota. The largest hail stone was hen size. There was also a video of wind damage on Middle Swan Lake, which is west of Avon.

Thunderstorm Wind in BROWN, MINNESOTA
From 28-MAY-18 14:54:00 to 28-MAY-18 14:56:00 (CST-6)
Location: GODAHL
Magnitude: 56.00 EG
Property damage: 30.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Severe down burst winds caused approximately 30 power poles to be sheared off on the east side of near County Road 115 and 6, southwest of Hanska, Minnesota. It also blew a small boat and car trailer off the road.

Thunderstorm Wind in CHIPPEWA, MINNESOTA
From 28-MAY-18 20:02:00 to 28-MAY-18 20:04:00 (CST-6)
Location: MONTEVIDEO
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Several trees and power lines were blown down around Montevideo.