Flash Flood — Imperial, California

2025-08-25 · near Mt Signal, Imperial, California

Event narrative

Video showed flooding along Highway 98 near Drew Road. Highway 98 was closed from Imperial Highway to Brockman Road due to the flooding. Timing estimated from radar.

Wider weather episode

The environment across southeast California on August 25th was primed for strong to severe thunderstorms with very moist and unstable conditions in place. The synoptic pattern featured a subtropical ridge of high pressure centered over northern New Mexico, while a Pacific trough to the west promoted upper level divergence over the region. These synoptic features also allowed for southerly moisture advection with PWATs climbing upwards of 1.8-2.0 inches. The broad ascent over the region combined with abundant moisture, MLCAPE values in excess of 1,000 to 2,000 J/kg, and DCAPE values in excess of 1,000 J/kg provided an environment conducive to strong to severe thunderstorms capable of producing damaging winds and flash flooding. Daytime heating allowed for continued destabilization with thunderstorms initiating midday across portions of Imperial County near the international border. These thunderstorms became strong to severe through the afternoon, producing numerous instances of wind damage as well as flash flooding, primarily across the Imperial Valley. The most significant flash flooding occurred along Highway 86 near Highway 78 when approximately 200 motorists became stranded in floodwaters. After being hit by damaging thunderstorms on both August 24th and 25th, the Imperial Irrigation District (IID) reported 311 downed power poles with damage estimates for the utility company upwards of 9 to 12 million dollars. Several schools across the Imperial Valley were closed on the 26th after sustaining damage from this event. No fatalities were reported during this event.

View location on OpenStreetMap → (32.6808, -115.6387)

Source: NOAA Storm Events Database, event_id 1292955. Narrative written by the NWS forecast office that issued the report.