Heavy Rains Drench Portions of Marshall County 
August 27-28, 2002

Heavy rain produced by slow moving thunderstorms deposited five to six inches of rain onto portions of western Marshall county during the evening hours of Tuesday, August 27 and  the early morning hours of Wednesday, August 28. This was in addition to approximately one inch of rain that had fallen just 24 hours earlier during the afternoon and evening of Monday, August 26. The highest reported 24-hour rainfall total for the August 27-28 storm was 5.61 inches at Argyle. Rainfall totals exceeded four inches in a 10 mile wide band dissecting Marshall county from the Red River to just east of Argyle. Widespread agricultural flooding was reported. Other communities  in northwestern Minnesota received heavy, albeit less intense, rainfall from these same storms. August 27-28 rainfalls totals include 3.26 inches at Crookston, 3.00 inches at Stephen, 3.00 inches at Warren, 2.90 inches at Karlstad, and 2.59 inches at Oslo.

In the affected areas, a 24-hour rainfall total of six inches is considered to be a one percent probability occurrence.

National Weather Service radar imagery can be used to estimate precipitation totals in near real-time. A private vendor (WSI) purchases radar data from the National Weather Service and utilizes the data to prepare the precipitation estimates offered in the hyperlinks below. Precipitation estimates from radar returns are often fraught with errors. Attenuation from heavy rain, enhanced reflection due to hail, and distance from the radar site, can cause radar-based estimates to over or under estimate true precipitation totals. For these reasons, this technology may never replace the need for ground-based precipitation measurements.

WSI radar-based precipitation estimate - 24 hour totals ending 7:00 AM, August 27
WSI radar-based precipitation estimate - 24 hour totals ending 7:00 AM, August 28

The State Climatology Office thanks Soil and Water Conservation Districts in the affected areas for their prompt and thorough response to our request for precipitation data. Data were also provided by the National Weather Service. We thank Minnesota's many volunteer precipitation monitors, whose diligent efforts make detailed analysis of storm events possible.

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URL: http://climate.umn.edu/doc/journal/flash_floods/ff020827-28.htm
Last modified: August 28, 2002