May 17, 2018
Thunderstorms developed over the east slopes of the Cascades and the Columbia Basin in a rich feed of wrap around moisture from an upper low over Oregon during the night of May 17th. These storms dumped a general quarter to half inch of rain over most of the western basin, but individual cells locally produced higher amounts with Ephrata measuring 0.72 inches. Local flash flooding and debris flows were noted from these storms.
Source: NOAA National Weather Service Storm Events Database (event 758680). Narrative written by NWS staff at the time of the event.
This event is one of many recorded floods in Grant County. See the full FEMA flood zone map, NFIP claim totals, and disaster history for the area.