Flash Flood — Yakima, Washington

2015-05-21 · near Selah, Yakima, Washington

Event narrative

Flooding in streets, 911 had some people evacuate buildings in fear of roof collapse. Police set up barricades to help divert drivers from flooded roadways, flooding in some homes. A few places lost power.

Wider weather episode

A large low pressure system off of southern California would spin up moisture to the area over several previous days. Embedded impulses would enhance convective activity leading up to the day. High CAPE and Perceptible Waters suggested thunderstorms with very heavy rainfall. Several areas across Yakima County WA recorded nearly an inch of rain in 30-60 minutes time. Enough dry air entrainment was available to produce a thunderstorm with a strong outflow boundary producing winds estimated to be 70 mph. These winds took down tree branches and uprooted some trees southwest of the city of Yakima.

View location on OpenStreetMap → (46.6578, -120.5261)

Source: NOAA Storm Events Database, event_id 567335. Narrative written by the NWS forecast office that issued the report.