Flash Flood — Allegan, Michigan

1997-06-20 to 1997-06-21 · near County-wide, Allegan, Michigan

Event narrative

Allegan County, which borders Ottawa County to the south, was impacted by the same slow-moving thunderstorms which trained across the area throughout the day of Friday, June 20th. The line of severe thunderstorms which moved across Allegan County Friday evening resulted in widespread flash flooding, with the worst of the flooding concentrated across the northern half of the county. The most significant damage occurred in the following Allegan County townships: Salem, Overisel, Hopkins, Wayland, Saugatuck, and Dorr. Notable rainfall totals for the 24 hours ending at midnight included 4.63 inches at Douglas, 5.40 inches at Allegan, 6.15 inches at Hamilton, and 7.20 inches at Wayland. Allegan County officials reported an extensive list of damage done to roads, drainage channels, homes, and businesses. Four people were injured, including a woman whose vehicle went nose-first into an 8-foot deep pit caused by a road washout. Extensive agricultural damage occurred in low-lying areas near flooded rivers and streams. Approximately 48 roads had near total or severe washouts (43 of which were closed for several days following the flooding). In addition, 126 roads had partial washouts. All totaled, 9 homes were destroyed, including 2 vacation cottages at Glenn Shores, 44 homes received major damage, and another 216 homes reported minor damage. Rain and draining groundwater caused a bluff along Lake Michigan at Glenn Shores, near Glenn, to collapse. The collapsing dune took several trees and 2 vacation cottages with it, 60 feet down onto the immediate lake shoreline. Eleven homes around Swan Lake in Cheshire Township were surrounded by water when the lake flooded. One business was destroyed, 7 reported major damage, and 30 received minor damage from flash flooding. The roof of the Regent Theater in the town of Allegan collapsed under the weight of rainwater. The 600-seat theater received major damage, but was not a total loss. The Otsego Lumber Company building also reported a roof collapse. Allegan County officials declared a local State of Emergency at 2:11 AM Saturday, June 21st, when they determined that local emergency recovery efforts were unable to handle the magnitude of the flooding situation. On Friday, June 27th, Governor John Engler issued a state disaster declaration for Allegan County.

Wider weather episode

During Friday, June 20th, very warm, moist and unstable air was in place across much of Michigan's Lower Peninsula, ahead of a strong, slow-moving cold front across the western Great Lakes region. Atmospheric conditions were ripe for the development of strong to severe thunderstorms containing wind gusts to 70 mph and very heavy rain. Numerous thunderstorms reached severe criteria due to damaging wind gusts. However, the most significant damage was caused by flash flooding across Allegan and Ottawa Counties, which was caused by the training effect of slow-moving thunderstorms during the day, followed by a line of severe thunderstorms which moved through during the early evening hours. Thunderstorms during the day saturated the soil across the counties, then heavy rainfall of 1 to 5 inches in a 2 hour period from a line of severe thunderstorms during the evening created extensive runoff, resulting in extensive flash flood damage.

Source: NOAA Storm Events Database, event_id 5618579. Narrative written by the NWS forecast office that issued the report.