BRANCH TOWNSHIP, Mich. — A new record for 24-hour precipitation has been set for the state of Michigan. The new record is 12.92 inches set on July 20 in Branch Township, about six miles east of Fountain in Mason County. The previous record was 9.78 inches in Bloomingdale in Van Buren County on August 31, 1914.
An extreme rainfall event occurred on July 20, with repeating thunderstorms developing and moving over the same areas for several hours. This was part of the same system that left more than 150,000 people without power and generated downburst winds in Jenison of 80 miles per hour. The hardest hit counties were Manistee, Mason, and Lake. Numerous official and unofficial reports of 4 to 10 inches were received from those counties. Multiple unofficial reports exceeded 12 inches in rural areas of Mason and Lake counties. Most of the rain fell over an 8 to 9 hour period during the morning hours of July 20.
The National Weather Service in Grand Rapids investigated an initial report of 13.53 inches received on July 20. A survey team visited the observer and calibrated the automated rain gauge. A slight overcatch was noted by the gauge, and an adjustment factor was determined using a gauge calibration kit. After the calibration, a final value of 12.92 inches was determined.
The National Weather Service recommended that the state climate extremes committee review the proposed state record precipitation value of 12.92 inches. The committee is comprised of five voting members representing local, state, and national climate experts. The committee met on September 13 and unanimously agreed to accept the 12.92 inches as the new state record 24 hour precipitation. NOAA’s National Centers for Environmental Information will be updating their website soon to reflect the new state record.
A special thanks to the Grand Rapids NWS for the information and facts contained here.
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