Tornadoes and Flooding in Iowa, May 18, 2000

The same frontal boundary meandering about Southern Iowa and Central Illinois lifted into Central Iowa and North Central Illinois by afternoon. A nearly stacked low center over the Mid Missouri River Valley underwent filling as it shifted eastward across Southern Iowa and Central Illinois. Much of Eastern Iowa along and south of U.S. Highway 30 was thrusted into the warm sector where temperatures climbed into the upper 70s to lower 80s. Meanwhile, areas north of the boundary were quite cool with a brisk northeast surface wind and plenty of cloud cover keeping temperatures down in the 60s. 12z soundings from KILX and KDVN indicated very steep lapse rates with Cape values of 2000-3000 J-kg. Thunderstorms quickly erupted along the boundary from Central Iowa through Northeast Iowa into Northern Illinois by late morning, and continued through the afternoon producing a few reports of large hail and torrential rain. Further south, a few supercells developed near Ottumwa. These supercells moved east into Washington...Jefferson and Iowa Counties producing large hail, high winds and a couple of brief, weak tornadoes in Iowa County. An F0 tornado touched down 3 miles northwest of Millersburg while another touched down several minutes later just west of North English. Both tornadoes were short lived and produced no damage. All auto dealerships in the city of Washington reported that nearly every car on their outside lots was damaged by the hail, which was as large as golfballs. Many homes suffered hail damage to siding, roofs and windows. The hail covered the ground in spots and was reported to have drifted as high as a foot up against the sides of some buildings in town. Damage to corn crops was minimal, while soybean crops were not as lucky, as many suffered extensive damage. Many acres had to be replanted. High winds were responsible for blowing a house trailer onto it's side while being transported north of Washington on Riverside Road. The supercell over Jefferson County weakened, while the Washington County supercell tracked northeast into Muscatine County producing golfball size hail, torrential rain, high winds and a few funnel clouds. Hail damaged several cars in Muscatine. High winds caved the roof in on a barn 6 miles west of Muscatine and scattered pieces of the wood structure across the farmland. The supercell then gradually weakened as it moved into the Quad Cities, but still managed to produce penny to golfball sized hail and high winds in Central and Western Scott County. Torrential rainfall on the order of 2 to 3 inches an hour led to localized street flooding throughout the Quad Cities and surrounding areas. When the storms hit the Quad Cities the temperature at the Davenport Municipal Airport plummeted from 83 to 55 degrees.