JACKSON, Wyo. — The National Weather Service in Riverton has issued a Flash Flood Watch for Teton County and all of Western Wyoming from noon until 11 p.m. on Monday. The threat for heavy rainfall and flash flooding on Monday will be higher compared to the previous threat on Friday and Saturday.
An organized disturbance moving through on Monday will trigger more numerous and widespread showers and thunderstorms compared to recent days. In addition, abundant monsoonal moisture remains in place along with weak steering winds aloft, both of which will result in a high threat for slow-moving thunderstorms capable of producing heavy rains.
The Tetons and surrounding mountain ranges in Western Wyoming and Eastern Idaho will see the highest threat for heavy rain, excessive runoff and flash flooding due to steeper terrain, but valley areas will see locally heavy rain amounts as well and could see some stream flooding or street flooding depending on exactly where heavier showers set up. Wildfire burn scars from recent years will be the most susceptible to runoff and mudslides from heavy rainfall.
Showers are developing already on Monday morning but will be most widespread in the afternoon and evening hours before tapering off after midnight. Drier conditions will arrive on Tuesday as monsoonal moisture exits the area, with only a slight chance of afternoon thunderstorms.
Alan Smith, Meteorologist