Flash Flood — La Salle, Louisiana

2025-08-29 · near Olla Arpt, La Salle, Louisiana

Event narrative

Flooding reported with high water covering the roadway at the intersection of Highway 124 and Thomas Drive.

Wider weather episode

Significant banding of heavy showers and thunderstorms with cell-training occurred on the morning of August 29th across East Texas and North Louisiana, posing the threat of flash flooding. A gradual increase in warm air advection and isentropic ascent was noted on the north side of a quasi-stationary frontal boundary and within a very moist and moderately unstable air mass. MUCAPE values ranged from 1000 to 2000 J/kg along the front from Deep East Texas into Central Louisiana. However, much of the elevated convection was rooted within the instability gradient farther north along the Arkansas/Louisiana border along with adjacent areas to the west and east. This was also where there was some modest frontogenesis and related forcing observed in the 925 to 850 millibar layer. In addition, precipitable water values were on the order of 2 to 2.25 inches and suggestive of a very tropical environment. The resulting heavy rain rates of 2 to 3 inches per hour led to numerous reports of flash flooding across parts of Northern and Central Louisiana.

View location on OpenStreetMap → (31.9044, -92.2240)

Source: NOAA Storm Events Database, event_id 1290811. Narrative written by the NWS forecast office that issued the report.