Alert archive / Louisiana / Severe Thunderstorm Warnings in 2004

Severe Thunderstorm Warning 35, NWS New Orleans, LA

April 11, 2004Plaquemines Parish, Louisiana

NWS New Orleans, LA issued this severe thunderstorm warning at Apr 11, 2004, 6:17 AM CDT for Plaquemines Parish, Louisiana. It was in force for 58 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: Apr 11, 2004, 6:17 AM CDT (11:17 UTC)
Expired: Apr 11, 2004, 7:15 AM CDT
In force: 58 min
Issued by: NWS New Orleans, LA
Area: Counties, with a storm outline in the text

County Plaquemines Parish, LA

Did it verify

Not verified. The Iowa Environmental Mesonet's Cow found no qualifying storm report inside this severe thunderstorm warning while it was in force. That is not proof nothing happened: reports are thin where few people live.

Cow counts a report within 15 km of the polygon while the warning was in force: a tornado for a tornado warning; hail of 1 inch or more, a gust of 58 mph or more or wind damage for a severe thunderstorm warning; a flash flood report for a flash flood warning.

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 00:00Z, 11.3 hours before the alert went out and 106 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: 779 J/kg
Mixed-layer CIN: -79 J/kg
Mixed-layer LCL: 1044 m above ground
0-6 km bulk shear: 46 kt
0-1 km storm-relative helicity: 83 m²/s²
0-3 km storm-relative helicity: 165 m²/s²
Significant tornado parameter: 0.3
Supercell composite: 3.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

000 
WUUS54 KLIX 111117
SVRNEW
LAC075-111215-

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE NEW ORLEANS LA
617 AM CDT SUN APR 11 2004

THE NATIONAL WEATHER SERVICE IN NEW ORLEANS HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  LOWER PLAQUEMINES PARISH IN SOUTHEAST LOUISIANA
  THIS INCLUDES THE CITY OF PORT SULPHUR

* UNTIL 715 AM CDT

* AT 611 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  LINE OF SEVERE THUNDERSTORMS FROM 13 MILES WEST OF PORT SULPHUR 
TO   29 MILES SOUTHWEST OF PORT SULPHUR...MOVING EAST AT 20 MPH.

LARGE HAIL AND DAMAGING WINDS ARE LIKELY WITH THIS STORM. TAKE COVER
IN A STURDY BUILDING AND STAY AWAY FROM WINDOWS.

REPORT SEVERE WEATHER TO THE NEAREST LAW ENFORCEMENT AGENCY. THEY
WILL RELAY YOUR REPORT TO THE NATIONAL WEATHER SERVICE FORECAST
OFFICE.

LAT...LON 2931 8968 2935 8983 2949 8996 2953 8954
          2944 8950 2940 8933 2898 8934 2893 8941

$$

24

What forecasters said that day

The local office's own words before this severe thunderstorm 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 severe thunderstorm warning went out at Apr 11, 3:45 AM CDT, 2 hours 32 minutes earlier.

Area forecast discussion, Apr 11, 3:45 AM CDT, 2 hours 32 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS/BATON ROUGE LA
345 AM CDT SUN APR 11 2004

.DISCUSSION...
LATEST SURFACE ANALYSIS SHOWED AN INVERTED TROUGH/WARM FRONT FROM
NORTH CENTRAL GULF TO SOUTHEAST LOUISIANA TO GEORGIA. THE COLD
FRONTAL BOUNDARY WAS FROM WEST CENTRAL MISSISSIPPI TO SOUTHEAST AND
SOUTH TEXAS. IR AND LIGHTNING DETECTION SYSTEM NOTED CONVECTION FROM
SOUTH TEXAS TO SOUTH CENTRAL LOUISIANA  AND FROM EAST
LOUISIANA TO CENTRAL ALABAMA. UPPER LEVEL DISTURBANCES WERE NOTED
OVER NORTHEAST LOUISIANA TO SOUTHEAST LOUISIANA...ANOTHER OVER JUST
SOUTHWEST OF BIG BEND TEXAS AND THE MAIN ONE OVER THE FOUR CORNERS
REGION.

THE FRONTAL BOUNDARY IS EXPECTED TO ENTER THE NORTHWEST ZONES BY 12Z
TODAY AND PUSH INTO THE COASTAL WATERS LATE TONIGHT. LOW LEVEL WINDS
AT 06Z FROM SOUNDING REMAINED WEAK FROM THE SOUTH 15 KNOT AT
850MB...NEAR CALM AT THE SURFACE. MOISTURE AXIS REMAINS ALONG THE
FRONT AND MAY FALL BEHIND THE FRONT ACROSS EAST TEXAS...NORTH
LOUISIANA AND NORTH MISSISSIPPI TONIGHT THROUGH MONDAY. MID LAYER
INSTABILITY SHOULD REMAIN ACROSS THE FORECAST AREA THROUGH MONDAY
DAY PERIOD. 06Z SOUNDING AT SLIDELL REVEALED A 5H TEMP OF -14C. THIS
IS SLIGHTLY LOWER THAN GFS...ETA AND NGM SOLN AT 18Z TODAY. WITH THE
POSSIBILITY OF A SLOW-MOVING FRONT AND COLD AIR ADVECTION AT
5H...OUR MAIN THREAT WILL HAIL AND HEAVY RAINFALL. WARM DRY SOILS
AND HIGH FLASH FLOOD GUIDANCE...FORECAST AREA SHOULD HANDLE EXPECTED
RAINFALL OF GENERALLY 1 TO 3 INCHES THROUGH TONIGHT. WILL KEEP HEAVY
RAIN WORDING ZONES FOR TODAY. COLD AIR ADVECTION SHOULD OCCUR MONDAY
DAY PERIOD. THE MOISTURE AXIS FINALLY SWEEP ACROSS THE FORECAST AREA
MONDAY NIGHT AS THE MAIN TROUGH DEEPENS AND MOVES ACROSS THE LOWER
MISSISSIPPI VALLEY TUESDAY. WILL LINGER POPS THROUGH TUESDAY.

&&

.MARINE...THE STRONG COLD FRONT AND SURFACE LOW MOVING ALONG IT WILL
CAUSE WINDS TO INCREASE TO NEAR SMALL CRAFT ADVISORY CRITERIA
TONIGHT OR MONDAY AND CONTINUING INTO TUESDAY AS COOL HIGH PRESSURE
BUILDS.

&&

.PRELIMINARY POINT TEMP/POPS...
MCB 69 54 63 45 / 90 60 50 30
BTR 70 55 63 47 / 90 60 50 30
MSY 74 60 67 50 / 90 50 40 30
GPT 73 59 64 50 / 90 50 40 30
&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
MS...NONE.
SE LA AND MS COASTAL WATERS...NONE.
&&

18

Hazardous weather outlook, Apr 10, 9:20 PM CDT, 8 hours 57 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE NEW ORLEANS LA
920 PM CDT SAT APR 10 2004

LAZ034>040-046>050-056>070-MSZ068>071-077-080>082-110100-
AMITE-ASCENSION-ASSUMPTION-EAST BATON ROUGE-EAST FELICIANA-HANCOCK-
HARRISON-IBERVILLE-JACKSON-LIVINGSTON-LOWER JEFFERSON-
LOWER LAFOURCHE-LOWER PLAQUEMINES-LOWER ST BERNARD-LOWER TERREBONNE-
ORLEANS-PEARL RIVER-PIKE-POINTE COUPEE-ST CHARLES-ST HELENA-ST JAMES-
ST JOHN THE BAPTIST-ST TAMMANY-TANGIPAHOA-UPPER JEFFERSON-
UPPER LAFOURCHE-UPPER PLAQUEMINES-UPPER ST BERNARD-UPPER TERREBONNE-
WALTHALL-WASHINGTON-WEST BATON ROUGE-WEST FELICIANA-WILKINSON-
920 PM CDT SAT APR 10 2004

THIS HAZARDOUS WEATHER OUTLOOK IS FOR EAST CENTRAL AND SOUTHEAST
LOUISIANA AND EXTREME SOUTHWEST...SOUTH CENTRAL AND COASTAL
MISSISSIPPI.

.DAY ONE...TODAY AND TONIGHT

NUMEROUS THUNDERSTORMS ARE EXPECTED TO DEVELOP LATER TONIGHT ACROSS
EAST CENTRAL LOUISIANA AND SOUTHWEST MISSISSIPPI. A CHANCE OF
THUNDERSTORMS WILL EXIST OVER SOUTHEAST LOUISIANA AND COASTAL
MISSISSIPPI.

A COLD FRONT WILL MOVE INTO THE REGION TONIGHT AND WILL HELP FOCUS
THUNDERSTORM DEVELOPMENT. WITH MARGINALLY UNSTABLE AIR AHEAD OF THE
BOUNDARY...ALONG WITH FAVORABLE WINDS IN THE UPPER ATMOSPHERE...A
FEW STRONG THUNDERSTORMS ARE POSSIBLE. THERE IS A SLIGHT RISK OF
SEVERE THUNDERSTORMS MAINLY TONIGHT TO THE NORTH AND WEST OF LAKE
PONTCHARTRAIN. THE MAIN SEVERE WEATHER THREAT WILL BE DAMAGING WINDS
AND LARGE HAIL.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

A COLD FRONT IS EXPECTED TO MOVE THROUGH SOUTHEAST LOUISIANA...
COASTAL MISSISSIPPI AND ADJACENT COASTAL WATERS SUNDAY MORNING.
NUMEROUS SHOWERS AND THUNDERSTORMS ARE EXPECTED SUNDAY AND SUNDAY
NIGHT. SOME STORMS MAY BE STRONG TO SEVERE SUNDAY MORNING...MAINLY
EAST AND SOUTH OF LAKE PONTCHARTRAIN INCLUDING THE MISSISSIPPI
COAST. THE MAIN SEVERE WEATHER THREAT WILL BE DAMAGING WINDS AND
LARGE HAIL.

SMALL CRAFT ADVISORY CONDITIONS MAY DEVELOP ACROSS THE GULF COASTAL
WATERS ON MONDAY AND CONTINUE INTO TUESDAY AS OFFSHORE WINDS INCREASE
TO 20 TO 25 KNOTS.

.SPOTTER INFORMATION STATEMENT...

THE ACTIVATION OF STORM SPOTTERS...HAM RADIO OPERATORS AND EMERGENCY
MANAGEMENT PERSONNEL...IN SUPPORT OF SEVERE WEATHER OPERATIONS...
MAY BE REQUESTED LATE THIS AFTERNOON OR THIS EVENING.

In the hours before

Local storm report, Apr 11, 6:05 AM CDT, 12 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
605 AM CDT SUN APR 11 2004

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

0430 AM     HAIL             DESTREHAN               29.96N 90.37W
04/11/2004  1.00 INCH        ST. CHARLES        LA   EMERGENCY MNGR

0430 AM     HAIL             HAHNVILLE               29.97N 90.42W
04/11/2004  1.00 INCH        ST. CHARLES        LA   EMERGENCY MNGR

0450 AM     HAIL             KENNER                  29.98N 90.25W
04/11/2004  1.00 INCH        JEFFERSON          LA   LAW ENFORCEMENT

0450 AM     HAIL             3 NE THIBODAUX          29.82N 90.79W
04/11/2004  1.75 INCH        LAFOURCHE          LA   LAW ENFORCEMENT

0520 AM     MARINE TSTM WIND LAKEFRONT KNEW ARPT     30.04N 90.03W
04/11/2004  60 MPH           ORLEANS            LA   OFFICIAL NWS OBS

0445 AM     HAIL             KENNER                  29.98N 90.25W
04/11/2004  1.50 INCH        JEFFERSON          LA   OFFICIAL NWS OBS

&&

18

Local storm report, Apr 11, 6:05 AM CDT, 12 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
605 AM CDT SUN APR 11 2004

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

0405 AM     HAIL             3 NE THIBODAUX          29.82N 90.79W
04/11/2004  1.75 INCH        LAFOURCHE          LA   LAW ENFORCEMENT

0430 AM     HAIL             DESTREHAN               29.96N 90.37W
04/11/2004  1.00 INCH        ST. CHARLES        LA   EMERGENCY MNGR

0430 AM     HAIL             HAHNVILLE               29.97N 90.42W
04/11/2004  1.00 INCH        ST. CHARLES        LA   EMERGENCY MNGR

0445 AM     HAIL             KENNER                  29.98N 90.25W
04/11/2004  1.50 INCH        JEFFERSON          LA   OFFICIAL NWS OBS

0450 AM     HAIL             KENNER                  29.98N 90.25W
04/11/2004  1.00 INCH        JEFFERSON          LA   LAW ENFORCEMENT

0520 AM     MARINE TSTM WIND LAKEFRONT KNEW ARPT     30.04N 90.03W
04/11/2004  60 MPH           ORLEANS            LA   OFFICIAL NWS OBS

&&

18

The office that day

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

Issued	Product	Office	Counties	Lasted
Apr 11, 2:33 AM CDT	Severe Thunderstorm Warning	LIX	Iberville	57 min
Apr 11, 3:48 AM CDT	Severe Thunderstorm Warning	LIX	Assumption, Lafourche, Saint James	57 min
Apr 11, 4:16 AM CDT	Special Marine Warning	LIX		119 min
Apr 11, 4:23 AM CDT	Severe Thunderstorm Warning	LIX	Saint Charles, Saint John the Baptist	52 min
Apr 11, 4:28 AM CDT	Severe Thunderstorm Warning	LIX	Terrebonne	62 min
Apr 11, 4:36 AM CDT	Severe Thunderstorm Warning	LIX	Lafourche	54 min
Apr 11, 4:39 AM CDT	Severe Thunderstorm Warning	LIX	Jefferson	51 min
Apr 11, 5:20 AM CDT	Special Marine Warning	LIX		115 min
Apr 11, 5:36 AM CDT	Severe Thunderstorm Warning	LIX	Jefferson, Lafourche, Plaquemines, Terrebonne	39 min
Apr 11, 6:07 AM CDT	Special Marine Warning	LIX		53 min
Apr 11, 6:24 AM CDT	Special Marine Warning	LIX		2 hr
Apr 11, 7:23 AM CDT	Special Marine Warning	LIX		2 hr
Apr 11, 7:23 AM CDT	Special Marine Warning	LIX		2 hr
Apr 11, 5:12 PM CDT	Special Marine Warning	LIX		93 min

Nearby

Severe Thunderstorm Warnings in Louisiana, 2004 Every severe thunderstorm warning in 2004

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.