Flash Flood — Tuolumne, California

2019-07-25 · near Aspen Vly, Tuolumne, California

Event narrative

Yosemite Park Rangers reported flash flooding near the Dana Creek and State Route 120 intersection at Tuolumne Meadows where 40 people were rescued when the river swelled and separated them from the highway.

Wider weather episode

Tropical moisture pushed up into central California along the west side of a large high pressure center which was positioned over the four corners region on July 24 and July 25. As the atmosphere destabilized in the afternoon, thunderstorms developed over the higher elevations of the Southern Sierra Nevada each day. While the thunderstorms on the afternoon of the July 24 were localized for the most part, measurable precipitation was more widespread on the afternoon of July 25 when scattered thunderstorms developed over the mountains. Some of these thunderstorms drifted westward into the Sierra foothills and the San Joaquin Valley. A few of the thunderstorms in the Sierra Nevada produced very heavy rainfall and flash flooding was observed at Tuolumne Meadows in Yosemite National Park. While amounts at most locations were generally a tenth of an inch of inch of less, a few locations in the Central Sierra in Tuolumne and Madera Counties picked up over half an inch of rainfall in three hours or less.

View location on OpenStreetMap → (37.8780, -119.3495)

Source: NOAA Storm Events Database, event_id 832053. Narrative written by the NWS forecast office that issued the report.