Flash Flood in Grant County, Washington

X-NE Road was covered by water and mud for approximately 100 to 150 yards and appeared to be deep in sections. It was likely that the road was impassable during the flash flood, but there were no reports of impacts during the event. Timing of the flash flood was estimated by radar.

An upper level low pressure system over western Oregon ejected a negatively tilted shortwave trough of lower pressure over the region during the evening hours of September 5th. Precipitable water values were twice the normal value for early September. A line of strong thunderstorms tracked across east-central Washington bringing strong winds and heavy rain. The hardest hit areas were across the Waterville Plateau, the Wenatchee area and east slopes of the northern Cascades. Strong winds did result in some fallen trees, but the greatest impact was due to the heavy rainfall. Training thunderstorms and intense rainfall resulted in flash flooding across multiple drainages. Recent burn scars from 2012 and 2013 wildfires also helped to create a damaging flash flood event.