Flash Flood — Tangipahoa, Louisiana

2016-08-12 to 2016-08-13 · near Greenlaw, Tangipahoa, Louisiana

Event narrative

Twelve to eighteen inches of rainfall over a 2 day period led to widespread flash flooding across roughly the northwestern half of Tangipahoa Parish. As water drained into the local rivers, record levels were recorded on the Tangipahoa and Natalbany Rivers. Additional details of the river flooding can be found in the flood report for the parish. As floodwaters rose, hundreds of high water rescues were necessary across the parish. On Friday the 12th, I-55 was closed due to high water near exit 40 in Independence and from exit 50 to exit 53 between Fluker and Arcoloa. More than 11,000 homes and businesses suffered various degrees of flooding, though it's difficult to determine how many were due to initial flash flooding and how many were due to subsequent river flooding. Two fatalities are attributed to the flash flooding in Tangipahoa Parish. A 49 year old man drowned when his vehicle left the road and ended up in flood waters off of Interstate 55 Friday morning. A 59 year old man drowned after being swept away by a strong current while walking along Hwy 440 near the town of Tangipahoa Friday afternoon.

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 → (30.9990, -90.5660)

Source: NOAA Storm Events Database, event_id 656655. Narrative written by the NWS forecast office that issued the report.