Tornado and Hail in Iowa, August 4, 1995

A moist and very unstable air mass was in place across Iowa. Lifted indices were in the -12° C. range by the early afternoon hours. Surface temperatures reached the middle to upper 80s with dew point readings in the lower to middle 70s. CAPE values over northern Iowa were around 3000 J-kg-1. Convection fired up during the late morning and early afternoon hours and left a weak outflow boundary over northern Iowa. During the early afternoon hours, convection fired over northwest Iowa. When this convection reached the old outflow boundary, one cell became severe at the intersection. In spite of weak inflow winds, generally 10 kts or less, the storm quickly grew and produced golf ball to baseball-size hail over Palo Alto County. WSR-88D VIL values reached 76 Kg-m-2 with this cell. Other storm fired in the areas, but did not become severe. The severe storm propagated south along its own outflow boundary. During this time the storm dropped copious amounts of hail. A report was received just north of Rush Lake, in Palo Alto County, of pea-size hail covering the ground to a depth of 12 inches in places. In spite of the small size of the hail, crop damage was severe with much of the crop shredded by hail. The new cell moved into northern Pocahontas County where it dropped softball-size hail. Damage was reported by these large hailstones to roofs and cars. Crop damage was also extensive. A short time later, another cell formed along the southern edge of the convective complex. It became severe and dropped only dime to quarter-size hail in spite of its VIL of 73 Kg-m-2. Following these events, the complex became too multicellular to sustain severe weather and only produced pea to marble-size hail and very heavy rains.

Sheriff officials reported a brief tornado touchdown.