Strong east-southeasterly pressure gradient flow between a strong high pressure over the mid-Atlantic and a weak surface low in the northwestern Gulf led to several days of coastal flooding across southeastern Louisiana. Reports varied from each day, with the most impacts during high tide cycles.
Every event with a place to put it; 4 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS LIX wrote it up.
Strong east-southeasterly pressure gradient flow between a strong high pressure over the mid-Atlantic and a weak surface low in the northwestern Gulf led to several days of coastal flooding across southeastern Louisiana. Reports varied from each day, with the most impacts during high tide cycles.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS New Orleans, LA wrote its last area forecast discussion before the first event at May 19, 3:06 AM CST, 5 hours 54 minutes earlier.
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</html>The national radar mosaic for the moment the first event began.
10 coastal flood. Local standard time, as filed.
Report from Orleans EOC that Venetian Isles had a few inches of water over roadways and earlier report of water over highways.
Report of normally dry areas in Riverland Heights near Airline Highway has water seeping up from storm drains. Highway 51 was closed north of Laplace near Lake Pontchartrain and I-55 along with all on and off ramps.
Report of many on and off ramps off of Interstate 10 and local roads were impassable, including LA 641.
Des Allemands and Bayou Gauche reporting very high water, with several roadways impassable.
Report of coastal flooding across Alligator Bayou and Bayou Bluff.
Areas near Chackbay and Bayou Gaugue had backwater flooding.
Highest water levels during previous two nights high tide cycles put about 6 inches of water on Highway 23. Typical east bank areas exposed to easterly winds had high water east of Alliance Refinery and between Jesuit Bend and Myrtle Grove. Highest water reported Thursday night between Whites Ditch and Phoenix.
Highest water levels during previous two nights high tide cycles put about 6 inches of water on Highway 23 extending down across areas of lower Plaquemines Parish.
Areas around Madisonville at Lakefront and one road in Lacombe reported to have water over roads.
Report that areas around and including Bayou Liberty has water over roadways from coastal flooding.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Louisiana in 2021Every state in 2021This day in weather historyWarnings in Louisiana, May 2021
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-10-01. Each event’s entry at NCEI: 960572, 960575, 960576, 960579, 960580, 960571, 960573, 960574, 960577, 960578.