WINONA, Minn. — Tornadoes Friday erupted from the violent collision of cold weather from southeast Minnesota and a warm front in western Wisconsin. National Weather Service stations in Rochester and LaCrosse confirmed eight touchdowns. One injury was reported: A trucker was injured, albeit not seriously, when a tornado near Stewartville flipped his rig on its side on Interstate 90. This was about 2:15 p.m. There also was a minor in Iowa from a separate band of storms. Winona County escaped the worst wrath: The most serious instability sweeping through northern townships without any touchdowns before sweeping into Wisconsin and Buffalo counties. Preliminary reports suggest 100 homes were damaged from the twin storm cells in Minnesota and Iowa, the Weather Service reported. The Minnesota-Wisconsin touchdowns, west to east:

> Sargent-Oslo (25 miles southwest of Rochester). 1:45 p.m. On ground five minutes, 3.0 miles. Rated EF0 in 40-78 mph range.

> Oslo. 1:53 p.m. On ground nine minutes, 3.9 miles. Rated EF0 in 40-78 mph range.

> Stewartville-Marion (11 miles south of Rochester) 2:17 p.m. On ground 17 minutes, 9.7 miles. Rated EF2 in 113-157 mph range.

> Potsdam (16 miles northeast of Rochester). 2:30 p.m. On ground 24 minutes, 12.1 miles. Rated EF1 in 73 to 112 mph. range.

> Plainview-Viola (near the Olmsted-Winona county line). 2:46 p.m. On ground 14 minutes, 7.5 miles. Rated EF2 jn 113-157 mph. range.

> Cream (10 miles east of Alma in Buffalo County, Wisconsin). 3:27 p.m. On ground 16 minutes, 8.6 miles. Rated EF3, at least 158 mph.

> Blair (in Jackson County 18 miles north of Galesville, Wisconsin). 4:08 p.m. On ground nine minutes, 5.7 miles. Rated EF1 at 100 mph.

> Requa (between Osseo and Fairchild, Wisconsin in extreme south Eau Claire County).  4:19 p.m. On ground five minutes, 4.6 miles.  Rated EF1 at 100 mph

How to rate tornadoes

Meteorologists use the Fujita scale to measure the intensity of tornadoes.

> EF5: 261 to 318 mph. Strong frame houses lifted off foundations, carried considerable distances, disintegrated. Automobile-sized missiles propelled 300 yards. Trees debarked. Steel reinforced concrete structures badly damaged.

> EF4: 207 to 260 mph. Well-constructed houses leveled. Structures blown off weak foundations.  Automobiles thrown. Large missiles airborne.

>  EF3: 158 to 207 mph. Roofs, walls torn off well-constructed houses. Forest leveled.

> EF2: 113 to 157 mph. Roofs torn off frame houses. Mobile homes demolished. Large trees snapped, uprooted. Light object become missiles.

> EF1: 73 to 112 mph. Road surfaces peeled off.  Mobile homes pushed off foundations, overturned. Moving autos pushed off the roads. Attached garages destroyed.

> EF0: 40 to 72 mph. Chimneys. rTree branches broken off. Shallow-rooted trees.  Billboards damaged.