Numerous showers and thunderstorms developed across southeast Louisiana as a moist and unstable atmosphere prevailed across the region and a weak and nearly stationary frontal boundary was draped across the area.
Every event with a place to put it. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS LIX wrote it up.
Numerous showers and thunderstorms developed across southeast Louisiana as a moist and unstable atmosphere prevailed across the region and a weak and nearly stationary frontal boundary was draped across the area.
The local office's own words before the first event, 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 the first event at Sep 23, 11:54 AM CST, 2 hours 36 minutes earlier.
AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE NEW ORLEANS LA 1254 PM CDT WED SEP 23 2009 .UPDATE... ...18Z AVIATION DISCUSSION... SCATTERED CONVECTION HAS FORMED ALONG AN INVERTED TROUGH AXIS EARLY THIS AFTERNOON. THIS CONVECTION WILL CONTINUE TO DEVELOP THROUGH THE AFTERNOON AND EARLY EVENING HOURS. HOWEVER...THE CONVECTION SHOULD DIE OFF SHORTLY AFTER SUNSET...DUE TO A LACK OF UPPER LEVEL FORCING. WITH THIS IN MIND...HAVE ADDED A TEMPO GROUP FOR THUNDER AT KMCB...KBTR...AND KMSY. HOWEVER...IT APPEARS THE AIRMASS IS A BIT DRIER AND MORE STABLE AT KGPT TODAY. HAVE LEFT OUT THUNDER FOR NOW TO REFLECT THE DRIER AIRMASS. HEADING INTO TONIGHT...AMPLE LOW LEVEL MOISTURE...COMBINED WITH LIGHT BOUNDARY LAYER WINDS ACROSS THE REGION WILL ALLOW FOR CEILING AND VISIBILITY RESTRICTIONS AT KMCB AND KBTR TONIGHT. A FAIRLY STRONG LOW LEVEL INVERSION WILL DROP VISIBILITIES INTO THE IFR RANGE...WITH CEILINGS POSSIBLY DROPPING INTO THE LIFR RANGE AROUND 10-12Z. THE INVERSION WILL BREAK AFTER 14Z...WITH MVFR CEILINGS EXPECTED TO LINGER 18Z. AT KMSY AND KGPT...A WEAKER INVERSION WILL KEEP MVFR AND VFR CONDITIONS IN PLACE. 32 && .PREV DISCUSSION... /ISSUED 1103 AM CDT WED SEP 23 2009/ DISCUSSION... SOUNDING DISCUSSION...NO PROBLEMS WITH THE FLIGHT THIS MORNING. VERY MOIST AND UNSTABLE THIS MORNING WITH A PW OF 2.35 INCHES AND AN LI OF -6.7. WITH THAT IN MIND...AND COMBINED DAYTIME HEATING WILL LIKELY ALLOW FOR NUMEROUS TO WIDESPREAD SHOWERS AND THUNDERSTORMS WITH THE POSSIBILITY OF VERY HEAVY RAINFALL AGAIN TODAY. WINDS ARE LIGHT FROM THE EAST NEAR THE SURFACE AND THE SOUTH...SOUTHWEST AT THE MIDDLE TO UPPER LEVELS. THE INVERTED TROUGH IS LOCATED ACROSS SERN LA AND INTO SRN MS(FROM NEAR HUM JUST WEST OF MSY AND NNW JUST WEST OF PIB). WE ARE STARTING TO HEAT UP AND ISLTD TO SCT SHRA ARE STARTING TO DEVELOP MAINLY AROUND THE SOUTH AND NORTH SHORE WITH ACTIVITY LIKELY BEGINNING IN THE RIVER PARISHES IN THE NEXT HOUR ALONG OUR INVERTED TROUGH. CONVECTION WILL BE COLD POOL/OUTFLOW DRIVEN AND LIKELY SPREAD SLOWLY INITIALLY. AS SEEN IN THE SOUNDING DISCUSSION THE ATMOSPHERE IS QUITE TROPICAL AND STORMS WILL BE QUITE EFFICIENT. ANY CONVERGING STORM OR BOUNDARIES COULD LEAD TO VERY HEAVY RAIN LOCALLY WITH RAINFALL ACCUMULATION APPROACHING 2 INCHES IN A SHORT TIME. CONVECTION WILL PERSIST INTO THE LATE AFT HRS BEFORE DECREASING IN COVERAGE AND INTENSITY A FEW HRS AFTER SUNSET. AS FOR STRONG/SVR...A FEW STRONG STORMS ARE POSSIBLE WITH MAINLY CONTINUOUS LIGHTNING AND GUSTY WINDS POSSIBLE BUT THE BIGGER CONCERN IS TORRENTIAL RAINFALL. NOT EXPECTING ANY SVR BUT THE ROGUE PULSE SVR STORM CANT BE RULED OUT. /CAB/ AVIATION... ISOLATED -SHRA CONTINUE TO TRACK ACROSS NWRN AREAS NEAR MCB AN BTR. LITTLE IF ANY IS REACHING THE GROUND. LOW CIGS WILL CONTINUE TO BE A PROBLEM MUCH OF THE MORNING HOURS AT BTR AND MCB. EXPECT VLIFR TO LIFR CIGS IN THESE LOCATIONS AND MVFR TO IFR AT GPT AND MSY. THE MORE SUBSTANTIAL ACTIVITY EXISTS IN NEAR SHORE GULF WATERS AND EAST OF PQL. SCT SHOWERS AND THUNDERSTORMS SHOULD BE ONGOING DURING THE LATER MORNING HOURS ACROSS THE AREA. SIMILAR CONDITIONS OCCURRED YESTERDAY AND SHOULD EXPECT MUCH OF THE SAME TODAY. THUNDERSTORM COVERAGE IS EXPECTED TO BECOME WIDESPREAD BY THIS AFTERNOON...ESP FROM GPT AND WESTWARD WITH BTR AND MCB LIKELY TO SEE THE MOST INTENSE AND LONGEST DURATION ACTIVITY. THE MAIN CONCERNS WILL BE HEAVY RAINFALL AND FREQUENT TO CONTINUOUS LIGHTNING. STORMS SHOULD BEGIN TO TAPER OFF NEAR SUNSET WITH CHANCE OF SH/TS THROUGH THE EVENING AND OVERNIGHT HOURS. WINDS THROUGH THE PERIOD SHOULD BE RELATIVELY LIGHT AT LESS THAN 10 KTS WITH DIRECTION DEPENDING ON THE LOCATION. STALLED/SLOW MOVING FRONTAL BOUNDARY ACROSS EAST CENTRAL LA WILL BE THE DIVIDER BTW NNW AND SE WINDS. MEFFER MARINE... PRESSURE GRADIENT PRODUCED BY COLD FRONT DRAPED ACROSS THE STATE HAS RESULTED IN WINDS STAYING ELEVATED. WINDS SHOULD BE GENERALLY EASTWARD THROUGH THE DAY. WIND SPEEDS WILL BE CLOSE TO THE SCS EXERCISE CAUTION CRITERIA AT AROUND 15 KNOTS. WILL HOLD OFF FOR NOW ON ISSUING BUT WILL MONITOR CLOSELY. SEAS DON/T APPEAR TO BE AN ISSUE WITH 1 TO 2 FEET NEAR SHORE AND 3 FEET OFFSHORE. BRIEF PERIODS OF HIGHER SEAS AND WINDS OVER 34 KNOTS WILL BE POSSIBLE NEAR STRONG THUNDERSTORMS TODAY. CONVECTION HAS BEEN QUITE SCATTERED THROUGH THE OVERNIGHT HOURS WITH A STAGNANT CLUSTER EAST OF CHANDELEUR ISLAND. STORMS SHOULD INCREASE IN COVERAGE WITH TIME ESPECIALLY THIS AFTERNOON ALTHOUGH INLAND AREAS WILL EXPERIENCE THE BULK OF CONTINUOUS RAINFALL. MAIN CONCERN WITH STORMS OVER COASTAL WATERS WILL BE HEAVY RAINFALL...FREQUENT LIGHTNING AND THE POTENTIAL FOR WATERSPOUTS. THE FRONT CAUSING THE UNSETTLED WEATHER ACROSS THE AREA WILL BECOME QUITE DISCERNIBLE LATER THIS WEEK BUT NERLY WINDS SHOULD EVENTUALLY PREVAIL AS HIGH PRESSURE BUILDS SLIGHTLY ACROSS TEXAS AND SHOVES THE BOUNDARY INTO THE GULF. RAIN CHANCES WILL CONTINUE THROUGH THIS WEEKEND. MEFFER && .PRELIMINARY POINT TEMPS/POPS... MCB 84 70 86 71 / 80 30 40 20 BTR 86 71 85 72 / 80 30 30 20 MSY 88 76 89 76 / 70 20 20 20 GPT 88 74 88 73 / 60 20 20 20 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...NONE. GM...NONE. MS...NONE. GM...NONE. &&
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE NEW ORLEANS LA 1109 AM CDT WED SEP 23 2009 GMZ530-550-555-570-575-LAZ034>040-046>050-056>070-MSZ068>071-077- 080>082-241615- 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- 1109 AM CDT WED SEP 23 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF COASTAL WATERS OF SOUTHEAST LOUISIANA AND SOUTH MISSISSIPPI...SOUTHEAST LOUISIANA AND SOUTHERN MISSISSIPPI. .DAY ONE...THIS AFTERNOON AND TONIGHT NUMEROUS SHOWERS AND SCATTERED THUNDERSTORMS ARE EXPECTED AGAIN TODAY...ESPECIALLY THIS AFTERNOON. FREQUENT TO CONTINUOUS LIGHTNING STRIKES AND HEAVY RAINFALL AMOUNTS OF ONE TO TWO INCHES WITH LOCALLY HIGHER AMOUNTS WILL BE POSSIBLE. SOME VERY HEAVY RAINFALL TOTALS MAY OCCUR IN A SHORT PERIOD OF TIME ESPECIALLY NEAR CONVERGING STORMS OR BOUNDARIES RESULTING IN HEAVY PONDING OF WATER AND LOCALIZED FLOODING OF ROADS AND LOW LYING AREAS. WATERSPOUTS WILL BE POSSIBLE ACROSS THE COASTAL WATERS...TIDAL LAKES...AND BAYS. SHOWERS AND THUNDERSTORMS WILL DIMINISH THIS EVENING. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY ISOLATED TO SCATTERED THUNDERSTORMS ARE EXPECTED THROUGH THE REMAINDER OF THE WORK WEEK WITH THE BEST CHANCE ON SATURDAY. THERE COULD BE A FEW STRONG TO LOCALLY SEVERE STORMS ON SATURDAY AS A WEAK COLD FRONT APPROACHES. MAIN CONCERNS WILL BE GUSTY TO DAMAGING WINDS...SMALL HAIL AND LIGHTNING. .SPOTTER INFORMATION STATEMENT... THE ACTIVATION OF STORM SPOTTERS...HAM RADIO OPERATORS...AND EMERGENCY MANAGEMENT PERSONNEL IN SUPPORT OF SEVERE WEATHER OPERATIONS IS NOT ANTICIPATED THROUGH TUESDAY...SEPTEMBER 29TH. HOWEVER...IF ANY HAZARDOUS WEATHER OCCURS PLEASE RELAY REPORTS TO THE NATIONAL WEATHER SERVICE BY CALLING 504 522 7330 OR 985 649 0357. CAB
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
124 PM CDT WED SEP 23 2009
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1100 PM FLASH FLOOD 5 NW OCEAN SPRINGS 30.46N 88.86W
09/22/2009 JACKSON MS COUNTY OFFICIAL
SEVERAL HOMES FLOODED DUE TO HEAVY RAINS IN THE CITY OF
ST MARTIN.
&&
CBANNANLAZ058-060-231945- SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE NEW ORLEANS LA 150 PM CDT WED SEP 23 2009 ...STRONG THUNDERSTORM NEARLY STATIONARY AFFECTING ST. JOHN THE BAPTIST PARISH...ST. CHARLES PARISH... AT 149 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A STRONG THUNDERSTORM 9 MILES NORTH OF RESERVE. THE THUNDERSTORM WAS NEARLY STATIONARY. THE PRIMARY THREAT FROM THIS STORM IS WIND GUSTS TO NEAR 40 MPH...WHICH COULD DOWN TREE LIMBS AND BLOW AROUND UNSECURED SMALL OBJECTS. SEEK SHELTER IN A SAFE HOME OR BUILDING UNTIL THIS STORM HAS PASSED. THIS STORM COULD PRODUCE RAINFALL AMOUNTS OF ONE TO TWO INCHES IN A SHORT PERIOD OF TIME...RESULTING IN PONDING OF WATER AROUND LOW LYING ROADWAYS. REMEMBER...DO NOT DRIVE YOUR VEHICLE INTO WATER COVERED ROADWAYS. THE DEPTH MAY BE TOO GREAT TO ALLOW A SAFE CROSSING.
LAZ056-232000- SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE NEW ORLEANS LA 206 PM CDT WED SEP 23 2009 ...STRONG THUNDERSTORM MOVING WEST AFFECTING ASSUMPTION PARISH... AT 204 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A STRONG THUNDERSTORM 6 MILES SOUTH OF NAPOLEONVILLE...OR ABOUT 5 MILES NORTHWEST OF LABADIEVILLE...MOVING WEST AT 10 MPH. THE STRONG THUNDERSTORM WILL BE NEAR... 6 MILES SOUTH OF PIERRE PART BY 300 PM... THE PRIMARY THREAT FROM THIS STORM IS FREQUENT LIGHTNING. SEEK SHELTER IN A SAFE HOME OR BUILDING UNTIL THIS STORM HAS PASSED. THIS STORM COULD PRODUCE RAINFALL AMOUNTS OF ONE TO TWO INCHES IN A SHORT PERIOD OF TIME...RESULTING IN PONDING OF WATER AROUND LOW LYING ROADWAYS. REMEMBER...DO NOT DRIVE YOUR VEHICLE INTO WATER COVERED ROADWAYS. THE DEPTH MAY BE TOO GREAT TO ALLOW A SAFE CROSSING.
LAZ038-039-MSZ070-232100- SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE NEW ORLEANS LA 300 PM CDT WED SEP 23 2009 ...STRONG THUNDERSTORM MOVING NORTH AFFECTING WASHINGTON PARISH... TANGIPAHOA PARISH...PIKE COUNTY... AT 256 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A STRONG THUNDERSTORM 17 MILES SOUTH OF MCCOMB...OR ABOUT 6 MILES NORTHWEST OF MOUNT HERMAN...MOVING NORTH AT 10 MPH. THE STRONG THUNDERSTORM WILL BE NEAR... MAGNOLIA BY 350 PM... MCCOMB AIRPORT...7 MILES SOUTHEAST OF MCCOMB AND 9 MILES SOUTHEAST OF SUMMIT BY 400 PM... THE PRIMARY THREAT FROM THIS STORM IS FREQUENT LIGHTNING. SEEK SHELTER IN A SAFE HOME OR BUILDING UNTIL THIS STORM HAS PASSED. THIS STORM COULD PRODUCE RAINFALL AMOUNTS OF ONE TO TWO INCHES IN A SHORT PERIOD OF TIME...RESULTING IN PONDING OF WATER AROUND LOW LYING ROADWAYS. REMEMBER...DO NOT DRIVE YOUR VEHICLE INTO WATER COVERED ROADWAYS. THE DEPTH MAY BE TOO GREAT TO ALLOW A SAFE CROSSING.
The national radar mosaic for the moment the first event began.
1 lightning. Local standard time, as filed.
Lightning struck an apartment building resulting in a fire in the attic of the building.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Louisiana in 2009Every state in 2009This day in weather historyWarnings in Louisiana, September 2009
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 197345.