Debris Flow — Lewis, Idaho

2019-04-09 · near Kamiah, Lewis, Idaho

Event narrative

Several mud slides were reported over Highway 12 just west of Kamiah on the morning of April 9th. One of the slides completely covered the road and caused the temporary closure of this primary road through the region while crews cleared the debris.

Wider weather episode

Beginning on April 6th and continuing through April 10th a series of Pacific atmospheric rivers were directed into Oregon, southeast Washington and central Idaho saturating the ground with heavy rainfall. During this 4 day period the COOP station at Kamiah reported 1.86 inches of rain, Elk River reported 2.94 inches of rain, Moscow 3.44 inches, Nez Perce 2.05 inches, Potlatch 2.46 inches, Dworshack Fish Hatchery 3.08 inches , the Lewiston Airport ASOS 0.93 inches and the ASOS at Pullman, WA recording 2.88 inches of rain. By the 9th of April widespread areal flooding issues from swollen streams and rivers as well as mud slides were noted around the region which persisted until the 11th when heavy rain ceased and rivers and streams began to recede.

Kamiah, ID suffered minor flooding of businesses, utilities and park land from the Clearwater River on the eastern boundary of the city and and the breaching of a levee on Lawyer Creek on the southern edge of the city. Lapwai Creek also overflowed it's banks threatening homes and flooding bottom lands and portions of State Highway 95 between Lapwai and Culdesac. Tribal officials of the Nez Perce reservation, which includes most of this region, declared a State of Emergency in response to this flooding event.

In the city of Moscow after receiving 1.47 inches of rain on April 9th, Paradise Creek rose to it's highest flood level on record causing extensive minor flooding of portions downtown Moscow. This flooding was aggravated by a Flash Flood running through residential neighborhoods and business districts laying in in gullies and ravines draining the saturated hills to the north of the city

The Palouse River also reached flood stage with inundation of bottom lands and fields along the river with some minor flooding of agricultural out buildings.

View location on OpenStreetMap → (46.2491, -116.0461)

Source: NOAA Storm Events Database, event_id 817299. Narrative written by the NWS forecast office that issued the report.