A very moist airmass aided the development of scattered thunderstorms during the afternoon hours each day. The slow movement of the thunderstorms produced several reports of flooding.
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.
A very moist airmass aided the development of scattered thunderstorms during the afternoon hours each day. The slow movement of the thunderstorms produced several reports of flooding.
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 Jul 25, 3:08 AM CST, 7 hours 56 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW ORLEANS LA 408 AM CDT MON JUL 25 2011 .DISCUSSION... LITTLE CHANGE IN THE CURRENT WEATHER PATTERN IS EXPECTED FOR THE FORECAST AREA FOR THE NEXT FEW DAYS. THERE WILL BE AMPLE OPPORTUNITIES FOR RAINFALL DURING THE WEEK AS A WEAK SHORTWAVE TROUGH OR WEAKNESS IN THE MID LEVELS LINGERS OVER THE SOUTHEAST AND GULF COAST REGION. THIS FEATURE WILL SLOWLY RETROGRADE ACROSS THE CENTRAL GULF COAST REGION DURING THE MID AND LATE WEEK PERIOD. PRECIPITABLE WATER VALUES WILL REMAIN WELL ABOVE TWO INCHES DURING THE WEEK...THEREFORE LOCALLY HEAVY DOWNPOURS WILL BE POSSIBLE EACH DAY. THE SHORTWAVE TROUGH WILL WEAKEN BY THE WEEKEND WITH MORE IN THE WAY OF RIDGING ALOFT BUILDING OVER THE GULF COAST REGION. THIS ALONG WITH SOMEWHAT DRIER AIR WORKING INTO THE AREA WILL ALLOW THE CONVECTION TO BECOME MORE SCATTERED IN NATURE OVER THE WEEKEND. TEMPERATURES HELD DOWN BY CLOUD COVER AND RAIN DURING THE WORK WEEK WILL RISE BACK INTO THE MIDDLE 90S OVER THE WEEKEND. A TROPICAL WAVE OVER THE CARIBBEAN IS EXPECTED TO WEAKEN AS IT MAKES ITS WAY INTO THE GULF AND IS EXPECTED TO HAVE MINIMAL INFLUENCE LOCALLY. 11 && .AVIATION... A WEAK LOW LEVEL INVERSION WILL CONTINUE TO BRING PATCHY FOG TO THE AREA THROUGH AROUND 13Z. THE FOG WILL BE MOST PREVALENT AT KHUM AND KMCB. VISIBILITIES MAY DROP TO AROUND 3SM AT THESE LOCATIONS BEFORE THE INVERSION LIFTS. AFTER THE INVERSION CLEARS...EXPECT VFR CONDITIONS TO BE THE RULE AT ALL OF THE TERMINALS. HOWEVER...AN UPPER LEVEL DISTURBANCE WILL STILL BE IMPACTING THE REGION. THIS DISTURBANCE...COMBINED WITH INCREASED INSTABILITY AFTER 16Z...WILL LEAD TO THE DEVELOPMENT OF SHOWERS AND THUNDERSTORMS. THIS CONVECTION WILL NOT LAST LONG AT EACH TERMINAL...BUT COULD PRODUCE BRIEF PERIODS OF IFR AND POSSIBLY LIFR RESTRICTIONS DUE TO LOWERED CEILINGS AND REDUCED VISIBILITIES. A TEMPO GROUP HAS BEEN ADDED TO THE FORECAST FOR THE AFTERNOON HOURS TO REFLECT THIS RISK OF CONVECTION. HEADING INTO TONIGHT...VERY SIMILAR CONDITIONS TO THOSE SEEN THIS MORNING ARE EXPECTED. 32 && .MARINE... VERY LITTLE TO TALK ABOUT CONCERNING THE MARINE FORECAST. IN GENERAL...LIGHT SOUTHERLY WINDS WILL BE THE RULE ACROSS THE MARINE ZONES. THESE LIGHT WINDS WILL KEEP SEAS FAIRLY CALM...WITH SEAS OF 1 TO 2 FEET EXPECTED OVER THE OUTER WATERS AND LESS THAN A FOOT IN THE SOUNDS AND LAKES. THE BIGGEST CONCERN WILL THE RISK OF EARLY MORNING CONVECTION DEVELOPING EACH DAY. GIVEN THE LIGHT OVERALL FLOW IN THE REGION...WATERSPOUTS WILL BE POSSIBLE EACH DAY AS THESE SHOWERS AND THUNDERSTORMS DEVELOP. 32 && .PRELIMINARY POINT TEMPS/POPS... MCB 89 74 89 73 / 60 30 60 30 BTR 89 75 90 75 / 60 30 60 30 ASD 89 75 89 75 / 60 30 60 30 MSY 89 76 88 76 / 60 30 60 30 GPT 89 76 89 75 / 60 30 60 30 PQL 89 73 89 73 / 60 30 60 30 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...NONE. GM...NONE. MS...NONE. GM...NONE. &&
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE NEW ORLEANS LA 1056 AM CDT MON JUL 25 2011 GMZ530-532-534-536-538-550-552-555-557-570-572-575-577-LAZ034>037- 039-040-046>050-056>072-MSZ068>071-077-080>082-260400- LAKE PONTCHARTRAIN AND LAKE MAUREPAS-MISSISSIPPI SOUND- LAKE BORGNE-CHANDELEUR SOUND-BRETON SOUND- COASTAL WATERS FROM PORT FOURCHON TO LOWER ATCHAFALAYA RIVER OUT 20 NM- COASTAL WATERS FROM THE SOUTHWEST PASS OF THE MISSISSIPPI RIVER TO PORT FOURCHON OUT 20 NM- COASTAL WATERS FROM BOOTHVILLE LA TO THE SOUTHWEST PASS OF THE MISSISSIPPI RIVER OUT 20 NM- COASTAL WATERS FROM PASCAGOULA MS TO STAKE ISLAND LA OUT 20 NM- COASTAL WATERS FROM PORT FOURCHON TO LOWER ATCHAFALAYA RIVER FROM 20 TO 60 NM- COASTAL WATERS FROM THE SOUTHWEST PASS OF THE MISSISSIPPI RIVER TO PORT FOURCHON FROM 20 TO 60 NM- COASTAL WATERS FROM STAKE ISLAND LA TO THE SOUTHWEST PASS OF THE MISSISSIPPI RIVER FROM 20 TO 60 NM- COASTAL WATERS FROM PASCAGOULA MS TO STAKE ISLAND LA FROM 20 TO 60 NM-POINTE COUPEE-WEST FELICIANA-EAST FELICIANA-ST. HELENA- 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-NORTHERN TANGIPAHOA- SOUTHERN TANGIPAHOA-WILKINSON-AMITE-PIKE-WALTHALL-PEARL RIVER- HANCOCK-HARRISON-JACKSON- 1056 AM CDT MON JUL 25 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF COASTAL WATERS OF SOUTHEAST LOUISIANA AND SOUTH MISSISSIPPI...SOUTHEAST LOUISIANA AND SOUTHERN MISSISSIPPI. .DAY ONE...TODAY AND TONIGHT NUMEROUS SHOWERS AND THUNDERSTORMS ARE EXPECTED AGAIN TODAY AND LOCALLY HEAVY RAINFALL AMOUNTS WILL BE POSSIBLE IN A RELATIVELY SHORT PERIOD OF TIME. GENERAL RAINFALL AMOUNTS BETWEEN A HALF INCH TO AN INCH WILL BE COMMON. HOWEVER...A FEW COMMUNITIES COULD RECEIVE AMOUNTS OF 2 TO 4 INCHES OF RAIN THROUGH THIS AFTERNOON. THESE AMOUNTS WILL CAUSE NUISANCE FLOODING IN RURAL AND URBAN SPOTS. SHOWERS AND THUNDERSTORMS WILL DIMINISH DURING THE EVENING HOURS. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY A WETTER THAN NORMAL PATTERN WILL PERSIST DURING MUCH OF THE REMAINDER OF WORK WEEK WITH NUMEROUS OCCURRENCES OF SHOWERS AND THUNDERSTORMS EXPECTED...ESPECIALLY DURING THE DAYTIME HOURS. LOCALLY HEAVY RAINFALL WILL REMAIN A THREAT. SEVERE THUNDERSTORMS ARE NOT EXPECTED...HOWEVER A FEW STRONG STORMS ARE POSSIBLE EACH DAY WITH STRONG GUSTY WINDS AND LIGHTNING STRIKES. WATERSPOUTS WILL BE POSSIBLE OVER THE TIDAL LAKES AND COASTAL WATERS. A SOMEWHAT DRIER PATTERN IS EXPECTED TO TAKE HOLD OVER THE WEEKEND WITH SHOWERS AND THUNDERSTORMS BECOMING MORE SCATTERED IN NATURE. THIS MEANS TEMPERATURES WILL BE RISING INTO THE MID 90S FOR HIGHS OVER MANY AREAS OVER THE WEEKEND WITH HEAT INDEX VALUES LIKELY REACHING OR EXCEEDING 105 DEGREES. .SPOTTER INFORMATION STATEMENT... THE ACTIVATION OF STORM SPOTTERS...HAM RADIO OPERATORS...AND EMERGENCY MANAGEMENT PERSONNEL IN SUPPORT OF SEVERE WEATHER IS NOT ANTICIPATED.
LAZ040-251415- SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE NEW ORLEANS LA 847 AM CDT MON JUL 25 2011 ...CLUSTER OF STRONG THUNDERSTORMS MOVING EAST AFFECTING ST. TAMMANY PARISH... AT 842 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A CLUSTER OF THUNDERSTORMS NEAR SLIDELL...OR ABOUT 4 MILES WEST OF SLIDELL...MOVING EAST AT 10 MPH. THE CLUSTER OF STRONG THUNDERSTORMS WILL AFFECT AREAS IN AND AROUND...SLIDELL AND LACOMBE. 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.
The national radar mosaic for the moment the first event began.
3 flash flood. Local standard time, as filed.
A few roads were reported closed in the Lacombe area due to flooding.
Several reports of street flooding were received from the Metairie area, including parts of Airline Highway, Jefferson Highway, and some smaller residential streets. Jefferson Highway was nearly impassible at Clearview.
Police reported street flooding of Loyola Drive and West Esplanade. Hooper Drive at Loyola Drive was also reported flooded.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Louisiana in 2011Every state in 2011This day in weather historyWarnings in Louisiana, July 2011
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: 322248, 322249, 322250.