Flash Flood — Lemhi, Idaho

2013-09-05 · near North Fork, Lemhi, Idaho

Event narrative

Very wet thunderstorms triggered flash flooding in the Kriley Creek drainage. This debris flow traveled over the northbound lane of highway 93 shutting it down for a period. The BLM road Kriley Gulch Rd was closed in the Kriley Creek drainage due to another separate washout.

Wider weather episode

Strong rising air associated with the nose of a 50 knot mid-level south-southwest jet combined with near record high moisture levels and an unstable atmosphere triggered wet multicellular thunderstorms over Lemhi County by late afternoon on September 5th. Flash flooding and power outages were the main impacts. To get an understanding how moist the air mass associated with this southwest surge was, the Boise weather balloon sounding recorded the 2nd highest moisture level (precipitable water values) on record on the evening of the 5th.

View location on OpenStreetMap → (45.3547, -113.9245)

Source: NOAA Storm Events Database, event_id 474232. Narrative written by the NWS forecast office that issued the report.