An area of rain and thunderstorms moved across extreme southeast Louisiana from near Assumption Parish to Lake Pontchartrain and the New Orleans area. Heavy rainfall of 3 to 8 inches fell during the overnight and morning hours.
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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.
An area of rain and thunderstorms moved across extreme southeast Louisiana from near Assumption Parish to Lake Pontchartrain and the New Orleans area. Heavy rainfall of 3 to 8 inches fell during the overnight and morning hours.
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 Dec 7, 11:54 PM CST, 1 hour 51 minutes earlier.
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1154 PM CST MON DEC 7 2009
.AVIATION...
A LARGE CLUSTER OF LIGHT TO MODERATE RAIN WILL CONTINUE TO
IMPACT SOUTHEAST LA AND EVENTUALLY COASTAL MS. A FEW THUNDERSTORMS
HAVE BEEN MOVING FROM SW TO NE JUST NORTH OF KPTN. ATTM...IT
DOESN/T APPEAR THAT ANY SITES WILL BE IMPACTED BY THE TSRA. BTR
MAY SEE VCTS BUT THAT SHOULD BE IT. VAD PROFILE SHOWS QUITE STRONG
WINDS JUST OFF THE SFC...30+KTS...BUT A RATHER GRADUAL TURNING OF
THE WINDS. SHOWERS SHOULD CONTINUE MUCH OF THE NIGHT. WINDS WILL
INCREASE SUBSTANTIALLY TUESDAY AFTER DAYBREAK WITH 15 TO 25 KTS
ACROSS THE AREA FROM A SOUTH TO SOUTHEAST WIND. STRONG
THUNDERSTORMS WILL BE POSSIBLE FROM LATE MORNING AND INTO THE
AFTN. CONDITIONS WILL IMPROVE LATE IN THE PERIOD BUT SHOULD STILL
HAVE REDUCED VIS AND CIGS IN THE MVFR CAT.
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 57 74 55 64 / 60 90 60 10
BTR 61 75 56 65 / 80 90 60 10
MSY 63 76 63 70 / 60 90 80 10
GPT 60 70 62 69 / 40 80 80 20
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
GM...SMALL CRAFT ADVISORY FROM 8 AM TUESDAY TO 3 AM WEDNESDAY FOR THE
FOLLOWING ZONES: COASTAL WATERS FROM THE SOUTHWEST PASS OF
THE MISSISSIPPI RIVER TO LOWER ATCHAFALAYA RIVER LA FROM 20
TO 60 NM...COASTAL WATERS FROM THE SOUTHWEST PASS OF THE
MISSISSIPPI RIVER TO LOWER ATCHAFALAYA RIVER LA OUT 20
NM...AND LAKE PONTCHARTRAIN AND LAKE MAUREPAS.
SMALL CRAFT ADVISORY FROM 8 AM TUESDAY TO 6 AM WEDNESDAY FOR THE
FOLLOWING ZONES: COASTAL WATERS FROM PASCAGOULA MS TO THE
SOUTHWEST PASS OF THE MISSISSIPPI RIVER FROM 20 TO 60
NM...AND COASTAL WATERS FROM PASCAGOULA MS TO THE SOUTHWEST
PASS OF THE MISSISSIPPI RIVER OUT 20 NM.
MS...NONE.
GM...SMALL CRAFT ADVISORY FROM 8 AM TUESDAY TO 3 AM WEDNESDAY FOR THE
FOLLOWING ZONES: COASTAL WATERS FROM THE SOUTHWEST PASS OF
THE MISSISSIPPI RIVER TO LOWER ATCHAFALAYA RIVER LA FROM 20
TO 60 NM...COASTAL WATERS FROM THE SOUTHWEST PASS OF THE
MISSISSIPPI RIVER TO LOWER ATCHAFALAYA RIVER LA OUT 20
NM...AND LAKE PONTCHARTRAIN AND LAKE MAUREPAS.
SMALL CRAFT ADVISORY FROM 8 AM TUESDAY TO 6 AM WEDNESDAY FOR THE
FOLLOWING ZONES: COASTAL WATERS FROM PASCAGOULA MS TO THE
SOUTHWEST PASS OF THE MISSISSIPPI RIVER FROM 20 TO 60
NM...AND COASTAL WATERS FROM PASCAGOULA MS TO THE SOUTHWEST
PASS OF THE MISSISSIPPI RIVER OUT 20 NM.
&&HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE NEW ORLEANS LA 757 PM CST MON DEC 7 2009 GMZ530-550-555-570-575-LAZ034>040-046>050-056>070-MSZ068>071-077- 080>082-081200- 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- 757 PM CST MON DEC 7 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF COASTAL WATERS OF SOUTHEAST LOUISIANA AND SOUTH MISSISSIPPI...SOUTHEAST LOUISIANA AND SOUTHERN MISSISSIPPI. .DAY ONE...TONIGHT ISOLATED THUNDERSTORMS ARE POSSIBLE MAINLY NEAR THE COAST AND ACROSS THE COASTAL WATERS WEST OF THE MISSISSIPPI RIVER. THE PRIMARY THREAT WILL BE OCCASIONAL LIGHTNING...WIND GUSTS 30 MPH AND BRIEF HEAVY RAINFALL. THUNDERSTORMS MAY INCREASE IN COVERAGE FARTHER INLAND TOWARDS DAYBREAK. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY THERE IS A SLIGHT RISK OF SEVERE WEATHER ACROSS THE ENTIRE OUTLOOK AREA TUESDAY AND TUESDAY NIGHT. THE MAIN CONCERN FROM SEVERE WEATHER WILL BE DAMAGING STRAIGHT LINE WINDS AND POSSIBLE TORNADOES. A DEEP SURFACE LOW IS EXPECTED TO MOVE INTO THE MID MISSISSIPPI VALLEY AND BRING A COLD FRONT THROUGH THE REGION TUESDAY NIGHT. AHEAD OF THE COLD FRONT ABUNDANT MOISTURE AND STRONG WINDS WILL BE IN PLACE. WITH MARGINAL INSTABILITY IN PLACE...A STRONG DISTURBANCE MOVING THROUGH THE CENTRAL PLAINS SHOULD HELP DEVELOP THUNDERSTORMS DURING THE DAY WITH A FEW BECOMING STRONG TO SEVERE. WITH THE AMOUNT OF SHEAR EXPECTED ANY DEEP THUNDERSTORM WILL HAVE THE CAPABILITY OF PRODUCING BOWING STRUCTURES AND/OR BECOMING A SUPERCELL. THIS WILL PRIMARILY BRING A RISK OF DAMAGING WINDS AND EVEN A OR TORNADO OR TWO. THE SEVERE RISK WILL END OVERNIGHT TUESDAY AFTER THE PASSAGE OF THE COLD FRONT. SMALL CRAFT ADVISORIES ARE LIKELY ONCE AGAIN TUESDAY THROUGH WEDNESDAY. SOUTHERLY WINDS WILL INCREASE TO AROUND 25 KNOTS TUESDAY AHEAD OF AN APPROACHING COLD FRONT. AFTER THE COLD FRONT PASSES WINDS WILL REMAIN STRONG FROM THE NORTHWEST. .SPOTTER INFORMATION STATEMENT... THE ACTIVATION OF STORM SPOTTERS...HAM RADIO OPERATORS...AND EMERGENCY MANAGEMENT PERSONNEL IN SUPPORT OF SEVERE WEATHER MAY BE NEEDED TUESDAY AND TUESDAY NIGHT...DECEMBER 8TH.
LAZ057>060-080745- SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE NEW ORLEANS LA 1254 AM CST TUE DEC 8 2009 ...LINE OF STRONG THUNDERSTORMS MOVING EAST AFFECTING ST. JOHN THE BAPTIST PARISH...ST. CHARLES PARISH...ST. JAMES PARISH...LAFOURCHE PARISH... AT 1253 AM CST...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A LINE OF STRONG THUNDERSTORMS FROM 17 MILES NORTH OF LAPLACE TO THIBODAUX...MOVING EAST AT 35 MPH. THE LINE OF STRONG THUNDERSTORMS WILL AFFECT AREAS IN AND AROUND... NORCO...HAHNVILLE...NEW SARPY...DESTREHAN...BOUTTE AND DES ALLEMANDS THE PRIMARY THREATS FROM THESE STORMS ARE FREQUENT LIGHTNING AND WIND GUSTS 40 TO 50 MPH...WHICH COULD DOWN TREE LIMBS AND BLOW AROUND UNSECURED SMALL OBJECTS. SEEK SHELTER IN A SAFE HOME OR BUILDING UNTIL THESE STORMS HAVE PASSED. THESE STORMS 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. BE PREPARED TO TAKE QUICK ACTION IF A WARNING IS ISSUED. STAY TUNED TO NOAA WEATHER RADIO OR YOUR FAVORITE LOCAL MEDIA OUTLETS FOR FURTHER DETAILS OR UPDATES FROM THE NATIONAL WEATHER SERVICE.
The national radar mosaic for the moment the first event began.
3 flash flood, 1 thunderstorm wind, 1 heavy rain. Local standard time, as filed.
Thunderstorm winds damaged a few roofs, fence and several small trees.
Heavy rainfall during the early morning hours overwhelmed local drainage with numerous houses and business reported flooded. 275 hours and 5 business were flooded with 50 of those houses reporting majore flooding. Hardest hit communities were Belle Rose, Paincourtville, and Pierre Part. 7.61 inches of rain was recorded at the emergency operations center in Napoleonville.
Heavy rainfall estimated between 4 to 7 inches during the morning hours caused widespread street flooding and water entering some homes. Between 15 and 20 houses had minor flooding.
Heavy rainfall of 4 to 7 inches overwhelmed local drainage and resulted in widespread street flooding and water entering buildings in the parish. A NWS cooperative ovserver reported 6.61 inches of rain.
Widespread street flooding occurred as a result of heavy rainfall. Nearly 7 inches of rainfall occurred in Slidell.
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, December 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: 209073, 209078, 209079, 209080, 209081.