Tornado and Hail in Iowa, May 4, 1994

A weak cold front sagged southeast into Iowa during the afternoon of the 4th. The dynamics were not very strong with the system, however the wind shear was sufficient enough to produce severe weather. Low level winds were from the south-southeast with the middle and upper level flow fairly strong northwest. Thunderstorms erupted during the afternoon. The early storms produced a tornado over Emmet County. The tornado tracked across several miles of open country before lifting north of Armstrong. No significant damage was reported as the track was over bare ground. The main severe weather associated with the storms was hail. Although the storms did produce gusty winds in the 40 to 50 mph range, no severe winds were reported. Golf ball-size hail fell north of Armstrong from the storm that produced the tornado. Other storms formed in a line extending southwest from the tornadic cell. Golf ball-size hail was also reported in Clay County at Royal. As the storms progressed further southeast, the hail size diminished but not the amount. What began as marble-size hail at Sioux Rapids in Buena Vista County grew to over an inch in diameter. The hail fell for about a half hour, accumulating to a depth of two to four inches. Hail accumulated to a depth of six inches in the town of Royal, giving the town a winter like appearance. Pea-size hail covered the ground north of Algona and also in the northwest corner of Calhoun County. In Calhoun County, southwest of Rockwell City, dime-size hail accumulated to a depth of one inch. By the late afternoon hours, the hail size had diminished to one-half inch or less. The storms tracked as far southeast as central Iowa before dissipating.