Alert archive / Louisiana / Flash Flood Watches in 2009

Flash Flood Watch 4, NWS New Orleans, LA

May 4, 20094 parishes in Louisiana; Pearl River County, Mississippi

NWS New Orleans, LA issued this flash flood watch at May 4, 2009, 10:17 AM CDT for 4 parishes in Louisiana; Pearl River County, Mississippi. It was in force for 4 hr.

The area

The counties it named.

The facts

Issued: May 4, 2009, 10:17 AM CDT (15:17 UTC)
Expired: May 4, 2009, 2:20 PM CDT
In force: 4 hr
Issued by: NWS New Orleans, LA
Flood severity: None

Counties Assumption Parish, LA, Saint Bernard Parish, LA, Saint James Parish, LA, Saint John the Baptist Parish, LA, Pearl River County, MS

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 12:00Z, 3.3 hours before the alert went out and 64 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: 2102 J/kg
Mixed-layer CIN: -2 J/kg
Mixed-layer LCL: 577 m above ground
0-6 km bulk shear: 36 kt
0-1 km storm-relative helicity: 170 m²/s²
0-3 km storm-relative helicity: 242 m²/s²
Significant tornado parameter: 1.6
Supercell composite: 9.9

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this flash flood watch 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 watch went out at May 4, 7:52 AM CDT, 2 hours 25 minutes earlier.

Area forecast discussion, May 4, 7:52 AM CDT, 2 hours 25 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
752 AM CDT MON MAY 4 2009

.UPDATE...
...TORNADO WATCH 238 IN EFFECT UNTIL 2 PM CDT...

ZONES UPDATED ACCORDINGLY. SEVERAL STRONG ROTATIONAL COUPLETS
NOTED ON RADAR AND WARNINGS APPEAR WARRANTED.

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
GM...SMALL CRAFT ADVISORY UNTIL 10 AM CDT THIS MORNING FOR GMZ555-575.

MS...NONE.
GM...SMALL CRAFT ADVISORY UNTIL 10 AM CDT THIS MORNING FOR GMZ575.

&&

24/RR

Hazardous weather outlook, May 4, 8:04 AM CDT, 2 hours 13 minutes before

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE NEW ORLEANS LA
804 AM CDT MON MAY 4 2009

GMZ530-550-555-570-575-LAZ034>040-046>050-056>070-MSZ068>071-077-
080>082-041700-
LAKE PONTCHARTRAIN AND LAKE MAUREPAS-
COASTAL WATERS FROM THE SOUTHWEST PASS OF THE MISSISSIPPI RIVER
TO LOWER ATCHAFALAYA RIVER LA OUT 20 NM-
COASTAL WATERS FROM PASCAGOULA MS TO THE SOUTHWEST PASS OF THE
MISSISSIPPI RIVER OUT 20 NM-
COASTAL WATERS FROM THE SOUTHWEST PASS OF THE MISSISSIPPI RIVER
TO LOWER ATCHAFALAYA RIVER LA FROM 20 TO 60 NM-
COASTAL WATERS FROM PASCAGOULA MS TO THE SOUTHWEST PASS OF THE
MISSISSIPPI RIVER FROM 20 TO 60 NM-POINTE COUPEE-WEST FELICIANA-
EAST FELICIANA-ST. HELENA-TANGIPAHOA-WASHINGTON-ST. TAMMANY-
IBERVILLE-WEST BATON ROUGE-EAST BATON ROUGE-ASCENSION-LIVINGSTON-
ASSUMPTION-ST. JAMES-ST. JOHN THE BAPTIST-UPPER LAFOURCHE-
ST. CHARLES-UPPER JEFFERSON-ORLEANS-UPPER PLAQUEMINES-
UPPER ST. BERNARD-UPPER TERREBONNE-LOWER TERREBONNE-
LOWER LAFOURCHE-LOWER JEFFERSON-LOWER PLAQUEMINES-
LOWER ST. BERNARD-WILKINSON-AMITE-PIKE-WALTHALL-PEARL RIVER-
HANCOCK-HARRISON-JACKSON-
804 AM CDT MON MAY 4 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF COASTAL WATERS
OF SOUTHEAST LOUISIANA AND SOUTH MISSISSIPPI...SOUTHEAST
LOUISIANA AND SOUTHERN MISSISSIPPI.

...TORNADO WATCH NUMBER 238 IS IN EFFECT FOR PORTIONS OF THE
   OUTLOOK AREA UNTIL 2 PM CDT...

.DAY ONE...TODAY AND TONIGHT

THUNDERSTORMS ALONG A COLD FRONT AND MOVING SLOWLY EASTWARD WILL
BECOME STRONG TO SEVERE THIS MORNING. THE PRIMARY THREAT WILL BE
TORNADOES AND DAMAGING STRAIGHTLINE WINDS. SOME SMALL
HAIL...FREQUENT LIGHTNING AND VERY HEAVY RAINFALL WILL ALSO
ACCOMPANY THESE STORMS AS THEY MOVE TO THE EAST AT 20 MPH.
THE THREAT SHOULD DIMINISH BY EARLY THIS AFTERNOON AS THE FRONT
MOVES EAST OF THE AREA.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

ISOLATED NON-SEVERE THUNDERSTORMS ARE POSSIBLE EACH AFTERNOON
THROUGH SATURDAY.

MINOR RIVER FLOODING WILL CONTINUE ALONG THE ATCHAFALAYA RIVER
NEAR MORGAN CITY UNTIL FURTHER NOTICE.

.SPOTTER INFORMATION STATEMENT...
THE ACTIVATION OF STORM SPOTTERS AND EMERGENCY OPERATIONS FOR
SEVERE WEATHER SUPPORT IS REQUESTED AT THIS TIME. PROMPTLY REPORT
ANY STORM DAMAGE TO THE NATIONAL WEATHER SERVICE OFFICE IN
SLIDELL.

24/RR

In the hours before

Local storm report, May 4, 6:57 AM CDT, 3 hours 20 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
657 AM CDT MON MAY 04 2009

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

0655 AM     TSTM WND DMG     2 W FRANKLINTON         30.85N 90.18W
05/04/2009                   WASHINGTON         LA   LAW ENFORCEMENT

            ROOF BLOWN OFF SHED AND TREES DOWN ACROSS SYLVEST ROAD.

&&

24/RR

Local storm report, May 4, 7:40 AM CDT, 2 hours 37 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
740 AM CDT MON MAY 04 2009

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

0635 AM     TSTM WND DMG     10 N POPLARVILLE        30.98N 89.53W
05/04/2009                   PEARL RIVER        MS   AIRPLANE PILOT

            TREES AND POWERLINES DOWNED NEAR THE INTERSECTION OF
            WAYNE PARDUE AND SPRING HILL ROADS. A MOBILE HOME WAS
            ALSO DAMAGED.

&&

MEFFERSO

Local storm report, May 4, 7:42 AM CDT, 2 hours 35 minutes before

PRELIMINARY LOCAL STORM REPORT...CORRECTED
NATIONAL WEATHER SERVICE NEW ORLEANS LA
742 AM CDT MON MAY 04 2009

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

0635 AM     TSTM WND DMG     10 N POPLARVILLE        30.98N 89.53W
05/04/2009                   PEARL RIVER        MS   LAW ENFORCEMENT

            TREES AND POWERLINES DOWNED NEAR THE INTERSECTION OF
            WAYNE PARDUE AND SPRING HILL ROADS. A MOBILE HOME WAS
            ALSO DAMAGED.

&&

MEFFERSO

Local storm report, May 4, 8:49 AM CDT, 1 hour 28 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
849 AM CDT MON MAY 04 2009

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

0843 AM     HAIL             5 SW GRAMERCY           30.01N 90.75W
05/04/2009  E1.00 INCH       ST. JAMES          LA   EMERGENCY MNGR

            LOCATION OF HAIL WAS IN VACHERIE

&&

FREVITTE

Special weather statement, May 4, 9:22 AM CDT, 55 minutes before

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Special weather statement, May 4, 9:43 AM CDT, 34 minutes before

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    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
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        The site you requested is temporarily down for maintenance or an unexpected outage.
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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 3, 11:14 PM CDT	Small Craft Advisory	LIX		11 hr
May 4, 5:43 AM CDT	Severe Thunderstorm Warning	LIX	Washington	32 min
May 4, 5:46 AM CDT	Areal Flood Advisory	LIX	Jefferson, Orleans, Saint Charles, Saint Helena, Saint John the Baptist, Tangipahoa and 1 more	73 days
May 4, 6:08 AM CDT	Tornado Warning	LIX	Tangipahoa, Washington	37 min
May 4, 6:14 AM CDT	Areal Flood Advisory	LIX	Ascension, East Baton Rouge, Iberville, Livingston, Saint Tammany, West Baton Rouge	76 days
May 4, 6:37 AM CDT	Severe Thunderstorm Warning	LIX	Ascension, Assumption, East Baton Rouge, Iberville, Livingston, Saint James and 1 more	53 min
May 4, 6:43 AM CDT	Tornado Warning	LIX	Washington	32 min
May 4, 7:14 AM CDT	Tornado Warning	LIX	Ascension, Assumption, Iberville, Saint James	46 min
May 4, 7:44 AM CDT	Tornado Warning	LIX	Livingston, Tangipahoa	31 min
May 4, 7:50 AM CDT	Severe Thunderstorm Warning	LIX	Washington	55 min
May 4, 7:55 AM CDT	Tornado Warning	LIX	Ascension, Assumption, Saint James, Saint John the Baptist	35 min
May 4, 8:27 AM CDT	Tornado Warning	LIX	Lafourche, Saint James, Saint John the Baptist	33 min
May 4, 8:45 AM CDT	Areal Flood Advisory	LIX	East Baton Rouge, Livingston, Washington, West Baton Rouge	83 days
May 4, 8:52 AM CDT	Tornado Warning	LIX	Lafourche, Saint Charles, Saint James, Saint John the Baptist	38 min
May 4, 9:00 AM CDT	Areal Flood Advisory	LIX	Assumption, Saint Charles, Saint James, Saint John the Baptist	83 days
May 4, 10:10 AM CDT	Severe Thunderstorm Warning	LIX	Assumption	22 min
May 4, 10:43 AM CDT	Severe Thunderstorm Warning	LIX	Jefferson, Lafourche, Plaquemines	47 min
May 4, 11:03 AM CDT	Areal Flood Advisory	LIX	Assumption, Lafourche, Saint Tammany, Terrebonne	84 days
May 4, 11:17 AM CDT	Special Marine Warning	LIX		88 min
May 4, 12:44 PM CDT	Special Marine Warning	LIX		91 min
May 4, 3:17 PM CDT	River Flood Warning	LIX	East Baton Rouge, Pointe Coupee, West Feliciana	44 days
May 4, 6:14 AM CDT	Severe Thunderstorm Warning	LIX	Pearl River	31 min

Nearby

Flash Flood Watches in Louisiana, 2009 Flash Flood Watches in Mississippi, 2009 Every flash flood watch in 2009

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.