Alert archive / Louisiana / Flash Flood Warnings in 2024

Flash Flood Warning 99, NWS New Orleans, LA

December 9, 20244 parishes in Louisiana

NWS New Orleans, LA issued this flash flood warning at Dec 9, 2024, 4:57 PM CST for 4 parishes in Louisiana. It was in force for 2 hr. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Dec 9, 2024, 4:57 PM CST (22:57 UTC)
Expired: Dec 9, 2024, 7:14 PM CST
In force: 2 hr
Issued by: NWS New Orleans, LA
Area: Storm-based polygon
Flood severity: None

Counties Ascension Parish, LA, East Baton Rouge Parish, LA, Livingston Parish, LA, West Baton Rouge Parish, LA

The radar

The Hammond radar (KHDC), 59 km from the middle of the area, began a volume at 22:56 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 12:00Z, 11.0 hours before the alert went out and 127 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 59 J/kg
Mixed-layer CIN: -78 J/kg
Mixed-layer LCL: 658 m above ground
0-6 km bulk shear: 62 kt
0-1 km storm-relative helicity: 385 m²/s²
0-3 km storm-relative helicity: 384 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this flash flood warning went out, 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 this flash flood warning went out at Dec 9, 3:30 PM CST, 1 hour 27 minutes earlier.

Area forecast discussion, Dec 9, 3:30 PM CST, 1 hour 27 minutes before

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In the hours before

Special weather statement, Dec 9, 2:02 PM CST, 2 hours 55 minutes before

Special Weather Statement
National Weather Service New Orleans LA
202 PM CST Mon Dec 9 2024

LAZ056-057-059-092030-
Assumption LA-St. James LA-Upper Lafourche LA-
202 PM CST Mon Dec 9 2024

...A STRONG THUNDERSTORM WILL IMPACT PORTIONS OF SOUTHERN ST. JAMES,
NORTHERN LAFOURCHE AND EASTERN ASSUMPTION PARISHES THROUGH 230 PM CST
...

At 202 PM CST, Doppler radar was tracking a strong thunderstorm
capable of producing funnel clouds near Chackbay, or 9 miles north of
Thibodaux, moving east at 25 mph.

HAZARD...Funnel clouds and winds in excess of 40 mph.

SOURCE...Radar indicated.

IMPACT...If a funnel cloud briefly touches down, minor damage to
         outdoor objects is possible. Gusty winds could knock down
         tree limbs and blow around unsecured objects.

Locations impacted include...
Lutcher, North Vacherie, South Vacherie, and Chackbay.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 3004 9069 2999 9067 2998 9068 2998 9066
      2995 9068 2995 9066 2990 9066 2988 9065
      2987 9091 2994 9093
TIME...MOT...LOC 2002Z 252DEG 22KT 2992 9087

FUNNEL CLOUDS...POSSIBLE
MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPH

KLG

Local storm report, Dec 9, 2:03 PM CST, 2 hours 54 minutes before

Preliminary Local Storm Report
National Weather Service New Orleans LA
203 PM CST Mon Dec 9 2024

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0201 PM     Flash Flood      2 ESE Mandeville        30.36N 90.05W
12/09/2024                   St. Tammany        LA   NWS Employee

            NWS employee sent a picture of flooding at
            the intersection of Albert and Florida in
            Mandeville.

&&

MEFFER

Local storm report, Dec 9, 2:05 PM CST, 2 hours 52 minutes before

Preliminary Local Storm Report
National Weather Service New Orleans LA
205 PM CST Mon Dec 9 2024

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0204 PM     Flash Flood      3 N Mandeville          30.42N 90.08W
12/09/2024                   St. Tammany        LA   NWS Employee

            NWS employed reported flooding on the
            Highway 190 service road near Judge Tanner.

&&

MEFFER

Special weather statement, Dec 9, 2:39 PM CST, 2 hours 18 minutes before

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Local storm report, Dec 9, 2:52 PM CST, 2 hours 5 minutes before

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Local storm report, Dec 9, 3:29 PM CST, 1 hour 28 minutes before

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The office that day

Everything else NWS New Orleans, LA issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Dec 9, 6:17 AM CST	Areal Flood Advisory	LIX	East Baton Rouge, Livingston, West Baton Rouge	111 min
Dec 9, 9:56 AM CST	Areal Flood Advisory	LIX	Ascension, Assumption, Iberville, Lafourche, Livingston, Saint Charles and 2 more	85 min
Dec 9, 11:21 AM CST	Flash Flood Warning	LIX	Ascension, Assumption, Livingston, Saint Charles, Saint James, Saint John the Baptist	6 hr
Dec 9, 11:36 AM CST	Areal Flood Advisory	LIX	Saint Tammany, Tangipahoa	4 hr
Dec 9, 12:13 PM CST	Flash Flood Warning	LIX	Saint Tammany	6 hr
Dec 9, 12:20 PM CST	Areal Flood Advisory	LIX	Ascension, Assumption, Iberville, Livingston	4 hr
Dec 9, 12:36 PM CST	Special Weather Statement	LIX	Saint James	24 min
Dec 9, 1:34 PM CST	Special Weather Statement	LIX	Assumption	41 min
Dec 9, 2:02 PM CST	Special Weather Statement	LIX	Saint James	28 min
Dec 9, 2:05 PM CST	Tornado Warning	LIX	Saint James, Saint John the Baptist	40 min
Dec 9, 2:39 PM CST	Special Weather Statement	LIX	Saint John the Baptist	36 min
Dec 9, 3:15 PM CST	Special Marine Warning	LIX		41 min
Dec 9, 3:35 PM CST	Small Craft Advisory	LIX		53 hr
Dec 9, 4:29 PM CST	Areal Flood Advisory	LIX	East Baton Rouge, Iberville, Livingston, Saint Helena, West Baton Rouge	3 hr

Nearby

Flash Flood Warnings in Louisiana, 2024 Every flash flood warning in 2024

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.