Heavy Rains and High Winds Pound Northern Minnesota
July 4 and 5, 1999

A complex of severe thunderstorms rumbled across northern Minnesota during the morning and early afternoon of July 4th. The thunderstorms brought damaging winds and torrential rain. Thunderstorms redeveloped during the evening of July 4th and continued into the early morning hours of July 5th. The later round of thunderstorms dropped large volumes of rain upon already waterlogged soils, leading to significant flooding.

The initial event began on the morning of the 4th with severe thunderstorms over eastern North Dakota. A 91 mph wind gust was recorded in Fargo, leading to numerous reports of structural damage. The storms raced across northern Minnesota and by lunchtime, were affecting the Iron Range and the Boundary Waters Canoe Area Wilderness. Millions of trees were blown down in the BWCA, in some cases leading to serious injuries of canoeists and campers. The path of the storms and some of their impacts can be tracked with Preliminary Local Storm Reports prepared by the National Weather Service shortly after the event.

The secondary event began just as July 4th fireworks were trying to get underway in many northland communities. The deluge continued into the early morning hours of the 5th. The heaviest rains were found in a wide area from Itasca to Cook Counties. Precipitation totals for many locations reached 4 to 6 inches. Some areas received 6 to 8 inch inches. The Weekly Precipitation, Departure, and Ranking Maps for July 6 indicate where the heaviest of the rains fell. Radar-based precipitation estimates (provided by the WSI Corporation) depict the 24 hour storm total. Some of the worst flooding occurred in central and southeast St. Louis, southern Cook, and southern Lake counties. The largest reported 24 hour precipitation total was 8.84 inches in west central St. Louis county. Many roads in St. Louis, Lake, and Cook counties were closed temporarily due to high water and washouts.


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URL: http://climate.umn.edu/doc/journal/990704.htm
Last modified: July 8, 1999