Hundred-Year Record Montana Rainfall Leads to Missouri River Flooding

Image (click to enlarge): Montana precipitation percentage of normal for 14 days ending 8 am EDT, May 31, from National Weather Service.

Record rainfall in Montana through the second half of May is threatening serious flooding on the Missouri River downstream into the Dakotas, Iowa, and Nebraska. Large portions of southeastern Montana have had rainfall as much as 600% of normal for the 14 days ending May 31.

From May 10 through the 25th, all-time May daily rainfall records were set at 10 locations in Montana. At Billings, where records extend back 76 years, the 3.12" on the 24th broke the previous May daily record of 2.83" set in 1952. Another 1952 record was broken at Livingston with 2.08" on the 24th. Two hundred-year records, originally set on May 26, 1911, were broken at Sidney with 2.42" and Ryegate with 2.21".

The 6.98" at Glasgow, Montana through this morning is a new monthly record for May, exceeding the 6.61" in 2007, and is 5.26" above the normal for the month. Glasgow climate records extend back to 1893.