Meteorological Synopsis
By mid-afternoon on April 30, a surface low pressure area was centered in Pierre, South Dakota. Several fronts stretched from the low pressure area with a stationary front located from north of Sioux Falls, South Dakota to near LaCrosse, Wisconsin. A warm front extended from south of Sioux Falls to near Des Moines, Iowa and St. Louis, Missouri. Between the two fronts, air temperatures had warmed into the 60s and low 70s and dew points in the 60s. Winds were quite strong in the area, with speeds from 15 to 25 mph from the east-southeast. By early evening, the warm front had moved to near the Minnesota-Iowa border. By 6:00 pm CDT, tornadoes began to develop along and just north of the warm front as it moved northward through northern Iowa and into southern Minnesota.
The towns of Albert Lea and Waseca were hardest hit.
Read more about this topic: 1967 Southern Minnesota Tornado Outbreak