Heavy Rain — Jefferson, Montana

2019-09-09 · near Clancy, Jefferson, Montana

Event narrative

Public reported a rainfall total of 2.25 inches at 2 N Clancy from September 6th through the 9th.

Wider weather episode

A couple of disturbances separated by brief shortwave ridging provided a four day stretch of wet weather for much of the region. The first system moved into southwest Montana on Friday, September 6th, 2019 and brought a brief period of strong to severe thunderstorms to the southwest followed by heavy rains, with some expansion into central and the eastern portions of North-central Montana. The second system moved toward the area by Sunday September 8th, 2019 and featured more general moderate to heavy rains over the Rocky Mountain Front and portions of Central Montana. Precipitable water values exceeded the one inch mark at times and rarely fell below .7 inches throughout this event. At the surface, a frontal system became nearly stationary and became an impetus for precipitation. The severe weather in the southwest was mostly driven by instability along with lift from the stalled frontal system and the first disturbance, while the second was largely influenced by easterly upslope winds.

View location on OpenStreetMap → (46.4990, -111.9800)

Source: NOAA Storm Events Database, event_id 851170. Narrative written by the NWS forecast office that issued the report.