The following events were reported: Flash Flood, Hail, Tornado. These occurred near station USW00013994, approximately 38.6523 km away, between 2011-04-22 18:36:00 and 2011-04-23 00:30:00. The events included records with hailstones measuring 0.815 inches.The events resulted in 1 injuries and 0 fatalities. No significant property or crop damage was reported. Episode Narrative: A strong cold front moved through region. With plenty of moisture, instability and decent low level shear, severe storms developed along the Interstate 70 corridor in Missouri and Illinois. Numerous reports of large hail and 5 tornadoes occurred with this event. One of the tornadoes was a long track one that moved through the St. Louis metropolitan area with it being rated an EF4, with only a few minor injuries and no deaths. Also, quite a bit of rain fell during this event and caused flash flooding. The flash flooding persisted for several days as additional rounds of heavy rain fell over the same region through the 26th of April. A strong cold front moved through region. Event Narrative: During the evening of Friday April 22nd, an intense supercell thunderstorm produced a long-track tornado which tore a path of destruction from west to east across the St. Louis Metropolitan Area, from St. Louis County Missouri eastward through the far northern portions of the City of St. Louis, then across the Mississippi River into Madison County Illinois. The tornado reached a maximum intensity of EF4 on the Enhanced Fujita Scale as it tracked through the community of Bridgeton, just west of Lambert St. Louis International Airport, in St. Louis County. The total path length was 21.3 miles, with a width of up to half a mile.||The tornado crossed the Mississippi River from the far northern portions of the City of St. Louis into Madison County Illinois approximately 1.5 miles south of Interstate 270 . The tornado continued east to half a mile north of the intersection of Illinois Route 203 and Pontoon Road. Damage east of this intersection included uprooted and snapped trees and three homes had roofs removed. At least one hundred homes were damaged in the area. The maximum damage found was in a neighborhood along Bern and Dawn Avenues. The tornadic damage then curved southeast and ended near the intersection of Alton Street and Pontoon Road. Damage width over this area varied from 50 to 150 yards with a path length of 5.1 miles. The damage east of Illinois Route 203 was rated low-end EF2. The highest wind speeds associated with the EF2 damage were approximately 120 mph. A tornado touched down on the north side of Waterloo, Illinois near the intersection of Leah Drive and James Street. Several homes and businesses sustained varying degrees of damage; from displaced roofing materials to businesses with structural damage. Two large air conditioners were tossed 30 yards from the roof of a business. Several large trees were snapped near the base of the trunk. Four power poles were snapped south of the intersection of North Market Street and Kolmer Avenue. One large garage was also destroyed behind a church with debris tossed southeastward 30 to 40 yards. The tornado skipped eastward and crossed Floraville Road on the north side of Ridge Club Golf Course then traveled down the first fairway. A number of cedar and pine trees were snapped. The tornado then crossed Ridge Road where several homes sustained minor roof damage, with 30 to 40 percent of the shingles removed. The tornado then traveled across the northern part of Konarcik Park. Numerous old growth pine trees were snapped at the base of the trunk. Trees three feet in diameter were common in this area. The tornado caused damage to the siding of one home near the intersection of Konarcik and Kopp Roads before lifting. There was one minor injury at Canterbury Manor Nursing Center due to flying glass when a window broke. The maximum intensity was low end EF2, with a maximum estimated wind speed of 115 mph. The maximum width of the tornado was 80 to 90 yards with a total path length of 3.5 miles. Up to three inches of rain fell in a short amount of time causing flash flooding. Several roads had water over them including Bluff Road near intersection with Trout Road. Several streets in Waterloo had 5 inches of water over them.