Flash Flood — Washington, Louisiana

2016-08-12 · near Mt Hermon, Washington, Louisiana

Event narrative

Eight to twelve inches of rain over a two day period led to flash flooding across northwestern Washington Parish as water drained into the Bogue Chitto River and its tributaries. Numerous roads were impassible and several homes suffered flood damage from Mount Hermon to Franklinton.

Wider weather episode

A slow moving low pressure system brought widespread showers and thunderstorms to the area. The system tapped into deep tropical moisture resulting in very intense rainfall across a large portion of the area. Two-day rainfall totals of 10 inches or more were common across areas generally to the west and northwest of Lakes Pontchartrain and Maurepas. The heaviest rainfall occurred across a swath of East Baton Rouge, Livingston, and St. Helena Parishes, where 20 to 30 inches fell over a 48-hour period, topping the 0.1% annual exceedance probability. The heavy rainfall led to widespread flash flooding and record river flooding. Many of the broken records had been set during the flooding of April 1983. In total, 12 people died in southeast Louisiana as a result of the flooding. The event was also responsible for an estimated total of ten billion dollars in damage across southern Louisiana and southern Mississippi. This estimate includes impacts of both the initial flash flooding and the resultant river flooding.

View location on OpenStreetMap → (31.0000, -90.3470)

Source: NOAA Storm Events Database, event_id 657314. Narrative written by the NWS forecast office that issued the report.