Alert archive / Louisiana / Special Weather Statements in 2020

Special Weather Statement, NWS New Orleans, LA

May 15, 2020Orleans Parish, Louisiana

NWS New Orleans, LA issued this special weather statement at May 15, 2020, 12:11 AM CDT for Orleans Parish, Louisiana. It was in force for 49 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 15, 2020, 12:11 AM CDT (05:11 UTC)
Expired: May 15, 2020, 1:00 AM CDT
In force: 49 min
Issued by: NWS New Orleans, LA

County Orleans Parish, LA

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 00:00Z, 5.2 hours before the alert went out and 55 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: 566 J/kg
Mixed-layer CIN: -4 J/kg
Mixed-layer LCL: 590 m above ground
0-6 km bulk shear: 25 kt
0-1 km storm-relative helicity: 204 m²/s²
0-3 km storm-relative helicity: 272 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 3.6

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 14, 11:59 PM CDT, 12 minutes earlier.

Area forecast discussion, May 14, 11:59 PM CDT, 12 minutes before

Area Forecast Discussion
National Weather Service New Orleans LA
1159 PM CDT Thu May 14 2020

.LONG TERM...
...Sunday through Thursday...
An upper level trough is expected over the Arklatex region by
Sunday with the surface low in the same general area. Divergent
flow is expected aloft across the forecast area. Surface base
capes 1000 to 1700j/kg will be in place over the Sunday. With the
associated axis rotating into the base of the trough, strong to
severe storms are possible across part of the forecast area with
damaging winds possible.

As the trough shifts east as an upper level low in the northern
stream will sag south and meander of the Tennessee valley through
mid next week. Lowered heights will keep forecast area below
normal from a temp perspective. Cloudiness will depend on how
close or far away the center of that low is.

&&

.AVIATION...
Scattered to numerous showers and thunderstorms will continue to
impact KNEW, KMSY, KHUM and possibly KGPT through at least 08z.
Convection should dissipate with time from west to east beginning
around 08Z with VFR returning through the overnight hours. A
repeat is expected tomorrow, so have added VCTS beginning around
15Z at TAF sites.

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...Small Craft Advisory until 4 AM CDT Friday for GMZ552-555-557-
     570-572-575-577.

MS...None.
GM...Small Craft Advisory until 4 AM CDT Friday for GMZ555-557-570-
     572-575-577.

&&

In the hours before

Special weather statement, May 14, 10:01 PM CDT, 2 hours 10 minutes before

Special Weather Statement
National Weather Service New Orleans LA
1001 PM CDT Thu May 14 2020

LAZ060-150330-
St. Charles-
1001 PM CDT Thu May 14 2020

...A STRONG THUNDERSTORM WILL AFFECT NORTH CENTRAL ST. CHARLES
PARISH...

At 1001 PM CDT, a strong thunderstorm was located over Destrehan,
moving north at 10 mph.

Winds in excess of 40 mph are possible with this storm.

Locations impacted include...
Hahnville, Norco, Ama, Destrehan, Luling, New Sarpy, St. Rose, Boutte
and Taft.

LAT...LON 2990 9045 3008 9041 3006 9037 3006 9030
      3005 9028 2989 9029
TIME...MOT...LOC 0301Z 186DEG 8KT 2994 9038

Local storm report, May 14, 10:39 PM CDT, 1 hour 32 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1039 PM CDT THU MAY 14 2020

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

1036 PM     FLASH FLOOD      5 SE ROBERT             30.45N 90.28W
05/14/2020                   TANGIPAHOA         LA   EMERGENCY MNGR

            MULTIPLE HOUSES AND BUSINESSES WITH WATER ENTERING ALONG
            HIGHWAY 22.

&&

CBANNAN

Special weather statement, May 14, 11:03 PM CDT, 1 hour 8 minutes before

Special Weather Statement
National Weather Service New Orleans LA
1103 PM CDT Thu May 14 2020

LAZ060>062-150445-
Orleans-St. Charles-Upper Jefferson-
1103 PM CDT Thu May 14 2020

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT CENTRAL ST. CHARLES...
WESTERN ORLEANS AND NORTHWESTERN JEFFERSON PARISHES...

At 1103 PM CDT, radar indicated strong thunderstorms were located
along a line extending from Destrehan to near Ama to 8 miles east of
Bayou Gauche. Movement was east at 15 mph.

Wind gusts up to 50 mph are possible with these storms.

Locations impacted include...
Avondale, Metairie, Hahnville, Marrero, Jefferson, Harahan, Westwego,
Jean Lafitte, Montz, Luling, River Ridge, Ama, Destrehan, Estelle,
St. Rose, Norco, Elmwood, Bridge City, Waggaman and Barataria.

LAT...LON 2975 9034 2987 9036 3003 9047 3005 9025
      3002 9016 2990 9009 2970 9011
TIME...MOT...LOC 0403Z 264DEG 14KT 2998 9035 2989 9028 2977 9028

Local storm report, May 14, 11:16 PM CDT, 55 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1116 PM CDT THU MAY 14 2020

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

1045 PM     FLASH FLOOD      MADISONVILLE            30.40N 90.16W
05/14/2020                   ST. TAMMANY        LA   LAW ENFORCEMENT

            HIGH WATERS RESCUES OCCURRING ALONG HWY 1077 IN
            MADISONVILLE AS HOMES AND VEHICLES ARE FLOODING.

&&

CBANNAN

Special weather statement, May 14, 11:28 PM CDT, 43 minutes before

Special Weather Statement
National Weather Service New Orleans LA
1128 PM CDT Thu May 14 2020

LAZ040-150515-
St. Tammany-
1128 PM CDT Thu May 14 2020

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT CENTRAL ST. TAMMANY
PARISH...

At 1127 PM CDT, radar indicated strong thunderstorms were located
along a line extending from 6 miles west of Bush to 7 miles east of
Abita Springs to Lacombe. Movement was east at 10 mph.

Winds in excess of 40 mph are possible with these storms.

Locations impacted include...
Slidell, Pearl River, Sun, Lacombe, Bush and Slidell Airport.

LAT...LON 3064 8987 3045 8970 3025 8966 3027 8997
      3049 8999 3067 9012
TIME...MOT...LOC 0427Z 280DEG 9KT 3061 9000 3048 8991 3032 8991

Special weather statement, May 15, 12:11 AM CDT, 0 minutes before

Special Weather Statement
National Weather Service New Orleans LA
1211 AM CDT Fri May 15 2020

LAZ059>064-069-150600-
Orleans-Lower Plaquemines-Upper St. Bernard-St. Charles-Upper
Lafourche-Upper Plaquemines-Upper Jefferson-
1211 AM CDT Fri May 15 2020

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT WEST CENTRAL ST.
BERNARD...SOUTHEASTERN ST. CHARLES...SOUTHWESTERN ORLEANS...EAST
CENTRAL LAFOURCHE...NORTHERN JEFFERSON AND NORTHWESTERN PLAQUEMINES
PARISHES...

At 1210 AM CDT, radar indicated strong thunderstorms were located
along a line extending from near Metairie to Harvey to near Jean
Lafitte to 6 miles northeast of Larose. Movement was east at 10 mph.

Winds in excess of 40 mph are possible with these storms.

Locations impacted include...
New Orleans, Metairie, Chalmette, Marrero, Harvey, East New Orleans,
Timberlane, Belle Chasse, Jefferson, Gretna, Westwego, Jean Lafitte,
Woodmere, Violet, Terrytown, Lafitte, Meraux, Bridge City, Poydras
and Estelle.

Torrential rainfall is also occurring with these storms, and may
cause localized flooding. Do not drive your vehicle through flooded
roadways.

LAT...LON 2961 9048 2975 9022 2989 9015 3003 9023
      3002 9018 3003 9003 3004 9003 3004 9000
      3008 8994 3008 8991 2986 8980 2980 8985
      2980 8983 2973 8986 2957 9021
TIME...MOT...LOC 0510Z 274DEG 8KT 3001 9013 2989 9007 2975 9014 2965
9033

The office that day

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

Issued	Product	Office	Counties	Lasted
May 14, 7:01 PM CDT	Tornado Warning	LIX	Saint Tammany, Tangipahoa	29 min
May 14, 7:08 PM CDT	Flash Flood Warning	LIX	Livingston, Saint Tammany, Tangipahoa	6 hr
May 14, 8:13 PM CDT	Special Marine Warning	LIX		32 min
May 14, 8:16 PM CDT	Special Marine Warning	LIX		29 min
May 14, 8:27 PM CDT	Flash Flood Warning	LIX	Ascension, Assumption, Saint James, Saint John the Baptist	3 hr
May 14, 8:28 PM CDT	River Flood Warning	LIX	Saint Tammany	49 hr
May 14, 9:05 PM CDT	Special Marine Warning	LIX		25 min
May 14, 9:32 PM CDT	River Flood Warning	LIX	Saint Tammany	68 hr
May 14, 9:46 PM CDT	Special Marine Warning	LIX		29 min
May 14, 10:01 PM CDT	Special Weather Statement	LIX	Saint Charles	29 min
May 14, 10:23 PM CDT	Flash Flood Warning	LIX	Lafourche, Saint Charles, Saint John the Baptist	5 hr
May 14, 11:03 PM CDT	Special Weather Statement	LIX	Saint Charles	42 min
May 14, 11:07 PM CDT	Areal Flood Advisory	LIX	Jefferson, Orleans, Plaquemines, Saint Bernard, Saint Charles	3 hr
May 14, 11:28 PM CDT	Special Weather Statement	LIX	Saint Tammany	47 min
May 14, 11:53 PM CDT	Flash Flood Warning	LIX	Jefferson, Orleans	3 hr
May 14, 11:58 PM CDT	River Flood Warning	LIX	Saint Tammany	33 hr
May 15, 1:16 AM CDT	Areal Flood Warning	LIX	Saint John the Baptist, Saint Tammany, Tangipahoa	104 min
May 15, 2:27 AM CDT	Flash Flood Warning	LIX	Jefferson, Lafourche, Terrebonne	3 hr
May 15, 4:07 AM CDT	Special Marine Warning	LIX		113 min
May 15, 9:46 AM CDT	River Flood Warning	LIX	Saint Tammany	34 hr
May 15, 3:04 PM CDT	Areal Flood Advisory	LIX	Tangipahoa	116 min

Nearby

Special Weather Statements in Louisiana, 2020 Every special weather statement in 2020

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.