Heavy Rain Update - September 16th, 2021 7 AM

Click HERE for an update concerning what is now Post-Tropical Cyclone (remnant low) Nicholas and the heavy rain threat for today through Friday night.

Changes from previous update:

• Rainfall estimates from last 72 hours or from 6 AM Monday to 6 AM Thursday indicated many portions of the area received 5 to 10 inches of rainfall with a few areas receiving over 10 inches. We will continue to verify these amounts as additional processing of radar estimates and gage readings are conducted.

• Numerous rivers are in minor to moderate flood stage with the Tchefuncte River at Folsom expected to cress above the major flood stage of 19 feet this morning.

• Additional rainfall through Friday night is expected to average 1 to 3 inches with locally higher amounts of 5 inches or greater possible where higher rainfall rates of 2 to 3 inches per hour occur.

• Coastal Flood Advisory is now in effect until 7 PM CDT today.

Overview:

WHAT: SLIGHT to MARGINAL RISK of Heavy Rain

WHEN:  Today through Friday Night

WHERE: Entire area

CONFIDENCE: 

• We are confident that additional bands of showers and thunderstorms will bring minor to moderate impacts in the form of locally heavy rainfall to portions of SE LA and coastal MS.

• Minor coastal flooding will continue through early this evening.

Impacts:

Rainfall/Flash Flooding:

• Additional rainfall of 1 to 3 inches is currently forecast with locally higher amounts possible through Friday evening. The highest rain rates of 1 to 3 inches per hour through Friday will produce the locally higher 5 inch or greater amounts.

• Expect ponding of water in low-lying areas and some localized flash flooding due to the very saturated grounds and high rainfall rates.

• Numerous rivers are in or going to minor to moderate flood stage, except the Tchefuncte River at Folsom is expected to crest above the major flood stage of 19 feet this morning.

Coastal Flooding:

• Elevated tides will continue today during the high tide cycle for most of coastal Southeast Louisiana and coastal Mississippi.

• 1 to 2 feet of inundation will be possible along immediate coastal areas. 

• Expect low-lying, coastal roads to be flooded and a few may become impassable.

The attached briefing highlights the threats associated with this system.

NWS New Orleans Website: www.weather.gov/neworleans

NWS New Orleans DSS Website: https://www.weather.gov/lix/embrief

River Gauges and Forecasts: http://water.weather.gov/ahps2/index.php?wfo=lix

NWS New Orleans Facebook: www.facebook.com/NWSNewOrleans

NWS New Orleans Twitter: https://twitter.com/NWSNewOrleans

Online Weather Reporting: https://www.weather.gov/lix/submit_storm_report

Request for information: Please relay any reports of flash flooding to our office ASAP.  You can send reports via NWSChat or by phone.  If emailing pictures, please send them to sr-lix.forecasters@noaa.gov.

Next Update and Contact Information:

The next update will be sent by 4PM this afternoon.  If you have any questions in the interim or need additional information, please do not hesitate to contact us.  We can be reached by phone at 504-522-7330 or 985-649-0429.  Use extension 4 to speak with a forecaster.  Alternatively, you can reach us by email by replying to this message or sending an email to sr-lix.forecasters@noaa.gov. Both methods will be delivered to the forecasters on shift at the office.