Alert archive / Louisiana / Special Weather Statements in 2021

Special Weather Statement, NWS New Orleans, LA

May 20, 2021Lafourche Parish, Terrebonne Parish, Louisiana

NWS New Orleans, LA issued this special weather statement at May 20, 2021, 4:58 PM CDT for Lafourche Parish, Terrebonne Parish, Louisiana. It was in force for 47 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: May 20, 2021, 4:58 PM CDT (21:58 UTC)
Expired: May 20, 2021, 5:45 PM CDT
In force: 47 min
Issued by: NWS New Orleans, LA

Counties Lafourche Parish, LA, Terrebonne Parish, LA

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 12:00Z, 10.0 hours before the alert went out and 119 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: 622 J/kg
Mixed-layer CIN: -1 J/kg
Mixed-layer LCL: 599 m above ground
0-6 km bulk shear: 19 kt
0-1 km storm-relative helicity: 152 m²/s²
0-3 km storm-relative helicity: 227 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

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What forecasters said that day

The local office's own words before this special weather statement 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 special weather statement went out at May 20, 4:16 PM CDT, 42 minutes earlier.

Area forecast discussion, May 20, 4:16 PM CDT, 42 minutes before

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In the hours before

Local storm report, May 20, 12:50 PM CDT, 4 hours 8 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1250 PM CDT THU MAY 20 2021

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

1230 PM     FLASH FLOOD      3 SW PRAIRIEVILLE       30.27N 91.01W
05/20/2021                   ASCENSION          LA   BROADCAST MEDIA

            WATER IN HOMES OFF OF RIDGE RD.

&&

DM

Local storm report, May 20, 1:42 PM CDT, 3 hours 16 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
142 PM CDT THU MAY 20 2021

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

1242 PM     FLASH FLOOD      4 S BAKER               30.52N 91.15W
05/20/2021                   EAST BATON ROUGE   LA   PUBLIC

            SEVERAL ROADS AROUND THE BATON ROUGE AIRPORT
            HAVE BEEN CLOSED DUE TO FLASH FLOODING .

1250 PM     FLASH FLOOD      4 E OAK HILLS PLACE     30.38N 91.02W
05/20/2021                   EAST BATON ROUGE   LA   PUBLIC

            ROAD CLOSED AT OLD PERKINS RD E & BARINGER
            FOREMAN RD.

1251 PM     FLASH FLOOD      GREENWELL SPRING        30.57N 90.99W
05/20/2021                   EAST BATON ROUGE   LA   PUBLIC

            SEVERAL ROADS CLOSED THROUGHOUT GREENWELL
            SPRINGS.

1255 PM     FLASH FLOOD      7 ENE PRAIRIEVILLE      30.33N 90.85W
05/20/2021                   ASCENSION          LA   PUBLIC

            ROADS CLOSED NEAR FRENCH SETTLEMENT DUE TO
            HIGH WATER AND FLASH FLOODING.

0100 PM     FLASH FLOOD      3 NNW PRAIRIEVILLE      30.34N 90.99W
05/20/2021                   ASCENSION          LA   PUBLIC

            SEVERAL ROADS CLOSED ALONG HWY 73 NEAR
            PRAIRIEVILLE DUE TO FLASH FLOODING.

&&

Local storm report, May 20, 4:01 PM CDT, 57 minutes before

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Special weather statement, May 20, 4:58 PM CDT, 0 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
May 19, 7:03 PM CDT	Special Weather Statement	LIX	Saint Tammany	42 min
May 19, 7:24 PM CDT	Special Marine Warning	LIX		81 min
May 19, 8:00 PM CDT	Severe Thunderstorm Warning	LIX	Saint Charles, Saint John the Baptist	25 min
May 19, 8:30 PM CDT	Special Marine Warning	LIX		30 min
May 19, 9:19 PM CDT	Areal Flood Advisory	LIX	Ascension, East Baton Rouge, Iberville, Livingston	116 min
May 20, 3:42 AM CDT	Special Weather Statement	LIX	Ascension, Assumption, Iberville, Jefferson, Plaquemines, Saint Charles and 3 more	63 min
May 20, 4:05 AM CDT	Special Marine Warning	LIX		55 min
May 20, 4:18 AM CDT	Special Marine Warning	LIX		57 min
May 20, 5:03 AM CDT	Special Marine Warning	LIX		57 min
May 20, 5:33 AM CDT	Special Marine Warning	LIX		57 min
May 20, 7:00 AM CDT	Special Weather Statement	LIX	Assumption, Jefferson, Lafourche, Saint Charles, Saint James	60 min
May 20, 7:39 AM CDT	Tornado Warning	LIX	Jefferson	8 min
May 20, 7:42 AM CDT	Special Marine Warning	LIX		33 min
May 20, 8:27 AM CDT	Special Marine Warning	LIX		63 min
May 20, 8:37 AM CDT	Areal Flood Advisory	LIX	Ascension, Assumption, East Baton Rouge, Iberville, Lafourche, Livingston and 3 more	52 min
May 20, 8:58 AM CDT	Tornado Warning	LIX	East Feliciana	13 min
May 20, 9:29 AM CDT	Flash Flood Warning	LIX	Ascension, East Baton Rouge, Iberville, Livingston, West Baton Rouge	9 hr
May 20, 9:45 AM CDT	Flash Flood Warning	LIX	East Baton Rouge, East Feliciana, Saint Helena, West Feliciana	11 hr
May 20, 10:04 AM CDT	Flash Flood Warning	LIX	Ascension, Assumption, Iberville, Lafourche, Livingston, Saint James and 1 more	13 hr
May 20, 10:52 AM CDT	Severe Thunderstorm Warning	LIX	Saint Charles, Saint John the Baptist	19 min
May 20, 11:22 AM CDT	Special Marine Warning	LIX		38 min
May 20, 11:26 AM CDT	Severe Thunderstorm Warning	LIX	East Baton Rouge, East Feliciana, Livingston, Saint Helena	94 min
May 20, 2:16 PM CDT	River Flood Warning	LIX	East Baton Rouge, Livingston	68 hr
May 20, 2:22 PM CDT	River Flood Warning	LIX	Ascension, Livingston	4 days
May 20, 2:33 PM CDT	Special Marine Warning	LIX		57 min
May 20, 2:40 PM CDT	River Flood Warning	LIX	East Baton Rouge	61 hr
May 20, 3:29 PM CDT	Special Marine Warning	LIX		61 min
May 20, 3:56 PM CDT	Gale Warning	LIX		19 hr
May 20, 3:56 PM CDT	Small Craft Advisory	LIX		60 hr
May 20, 3:56 PM CDT	Wind Advisory	LIX	Orleans, Saint Bernard, Saint John the Baptist, Saint Tammany	27 hr
May 20, 4:30 PM CDT	Special Marine Warning	LIX		90 min
May 20, 5:16 PM CDT	Areal Flood Advisory	LIX	Assumption, Jefferson, Lafourche, Terrebonne	3 hr
May 20, 6:42 PM CDT	Flash Flood Warning	LIX	Ascension, East Baton Rouge, Iberville, Livingston, Saint Helena, West Baton Rouge	4 hr

Nearby

Special Weather Statements in Louisiana, 2021 Every special weather statement in 2021

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.