Flood in Blaine County, Montana

Broadcast media reported minor flooding at the Blaine county fairgrounds. Standing water upwards of 6 inches in spots was reported.

A closed upper low over the Great Basin and vicinity shifted northeastward toward the region while it spawned a surface low across eastern MT. As the upper level disturbance and surface low became stacked across eastern MT, a period of widespread heavy rain developed where the TROWAL set up across the eastern plains. Additionally, a few strong northwesterly gusts were observed on the west side of the surface low. Overall, the soil was quite dry before the onset of the event, which allowed for heavy rain to be largely beneficial.

Rain amounts from this event were greatest across the eastern plains (Fergus, Blaine, Hill, Chouteau, and Judith Basin counties), largely ranging between 2 and 5 inches, with a few reports of upwards of 7 and a half inches. Areas that reported rain in excess of 6 inches include 10 S of Chinook in Blaine county (7.42), 5 NE Hilger in Fergus county (7.25), 2 S Chinook in Blaine county (6.6), and 7 SE Lewistown in Fergus county (6.5). ASOS station KLWT Lewistown Airport measured 4.35 over 24 hours during the calendar day of September 18 (Standard time), which was the second highest single day precipitation total on record in the Lewistown climate records.