Flash Flood — Mariposa, California

2018-03-22 · near Coulterville, Mariposa, California

Event narrative

Mariposa Office of Emergency Services reported several homes flooded and roadways washed out. While many roadways were washed out across Northwestern Mariposa County, the homes were generally impacted near Lake Don Pedro, Hornitos, and the City of Mariposa. The two fatalities that did occur in the area were both related to a person driving into a flooded roadway. One was along highway 132 west of Coulterville and the other was near Cathey's Valley where a 72 year old woman was found dead nearly four months later.

Wider weather episode

A warm plume of moist tropical air brought a very active period of weather to the area between the evening of March 20 and the evening of March 22. This resulted in widespread heavy rainfall across the area on March 21 and 22 which produced flooding at many locations with rock slides and debris flows closing several roads across the area. The most impacted areas being around Mariposa as a result of the Detwiler Fire burn scar and Springville as a result of the Pier Fire burn scar. In addition, thunderstorms developed during the afternoon of March 22 producing flash flooding at many locations as well as funnel clouds. A Flash Flood Emergency was issued for most of western Mariposa County where several buildings were flooded and some areas were evacuated. A small tornado briefly touched down near Dinuba in Tulare County. In addition, several feet of new snow fell above 9000 feet. Below the snow line, much of the Southern Sierra Nevada measured between 4 and 8 inches of rainfall while most of the San Joaquin Valley picked up between 1 and 3 inches of rainfall.

View location on OpenStreetMap → (37.7122, -120.3480)

Source: NOAA Storm Events Database, event_id 740496. Narrative written by the NWS forecast office that issued the report.