BOZEMAN – Deeper layer of monsoonal moisture is lifting from the South into SW Montana for the second day in a row but this time the area of concern will be east of I-15.
Sunday slow moving monsoon thunderstorms produced localized pockets of heavy rain and a few flash flood warnings were issued. Reports of a half an inch to three quarters of an inch of rain were observed over SW Montana west of I-15. That might sound good, but the rainfall was isolated and not widespread.
Monday that plume of moisture is drifting slowly to the east. This is the same setup as Sunday, but the slow-moving thunderstorms are most likely east of I-15.
The National Weather Service has a FLASH FLOOD WATCH up through midnight tonight for most of SW Montana. This means slow moving thunderstorms capable of producing heavy rain may result in flash flooding. Including debris flows in burn scar areas.
Within the watch area look for flash flood warnings. This upgrade to a warning means flash flooding is occurring and could threaten property and life.
Starting Tuesday this wonderful monsoonal moisture will be exiting the region and we should see a return of dry and warm to hot weather return. This will also bring back more wildfire smoke so look for worsening air quality conditions.