Alert archive / Louisiana / Areal Flood Advisories in 2011
Areal Flood Advisory 21, NWS New Orleans, LA
NWS New Orleans, LA issued this areal flood advisory at Jul 18, 2011, 5:35 AM CDT for 4 parishes in Louisiana. It was in force for 115 min.
The area
The counties it named.
The facts
- Issued
- Jul 18, 2011, 5:35 AM CDT (10:35 UTC)
- Expired
- Jul 18, 2011, 7:30 AM CDT
- In force
- 115 min
- Issued by
- NWS New Orleans, LA
- Area
- Storm-based polygon
Counties Jefferson Parish, LA, Orleans Parish, LA, Plaquemines Parish, LA, Saint Bernard Parish, LA
The nearest sounding before it
Slidell Radar S, LA (KSIL), launched 00:00Z, 10.6 hours before the alert went out and 55 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.
- Mixed-layer CAPE
- 1688 J/kg
- Mixed-layer CIN
- -11 J/kg
- Mixed-layer LCL
- 638 m above ground
- 0-6 km bulk shear
- 20 kt
- 0-1 km storm-relative helicity
- 1 m²/s²
- 0-3 km storm-relative helicity
- 37 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 1.2
What forecasters said that day
The local office's own words before this areal flood advisory 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 areal flood advisory went out at Jul 18, 4:38 AM CDT, 57 minutes earlier.
Area forecast discussion, Jul 18, 4:38 AM CDT, 57 minutes before
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW ORLEANS LA 438 AM CDT MON JUL 18 2011 .SHORT TERM... MOISTURE AXIS IS OBVIOUS THIS MORNING AND SOUNDINGS CONTINUE TO SUPPORT A DEEP MOIST ENVIRONMENT. PW'S REMAIN ABOVE 2.25" UNTIL TUESDAY WHEN THEY DROP BACK UNDER 2". LIGHT BOUNDARY LAYER WIND SPEEDS...LOW CONVECTIVE TEMPS AND LOW LCL LEVELS MAKE THIS ANOTHER DAY THAT WATERSPOUTS CAN BE PRODUCED. MOST OF THESE WILL REMAIN OVER OPEN WATER...BUT THE POTENTIAL...AS USUAL...WILL BE THAT ONE OR TWO COULD MAKE A BRIEF VISIT ONSHORE. MARINERS AND INDIVIDUALS SHOULD WATCH FOR WATERSPOUTS AND AVOID THEM. ISOLATED RAINFALL AMOUNTS ARE EXPECTED TO BE HEAVY AGAIN TODAY AND WILL RANGE BETWEEN 3 TO 5 INCHES. THE MAIN AREAS TO BE AFFECTED SHOULD FROM COASTAL MISSISSIPPI BACK THROUGH SOUTHEAST LA AROUND AND SOUTH OF LAKE PONTCHARTRAIN. AREAS OF RAIN WILL BEGIN TO MOVE AWAY FROM COASTAL MISS AFTER NOON TODAY. RIDGE WILL DO ITS BEST TO BUILD INTO THE SE CONUS THROUGH MID WEEK AND AFFECT US BY WARMING THINGS UP AND CLEARING US OUT FOR THE MOST PART. SOME MOISTURES COMES BACK TOWARD THE END OF THE WEEK THOUGH. && .AVIATION... WIDESPREAD SHOWERS AND THUNDERSTORMS HAVE DEVELOPED ALONG A LINE FROM GPT TO NOT TOO FAR SOUTH OF MSY. THIS ACTIVITY WILL PERSIST FOR THE NEXT SEVERAL HOURS AND LIKELY SPREAD WESTWARD WITH TIME LATER THIS MORNING. MORE SCATTERED STORMS ARE EXPECTED TO DEVELOP ACROSS THE REST OF THE AREA BY LATE MORNING AND INTO THE AFTERNOON. MEANWHILE...SCT MVFR DECK WILL LIKELY PERSIST TODAY AREAWIDE WITH LOWER CIGS AROUND STORMS. VERY INTENSE RAIN IS POSSIBLE NEAR THE CORE OF CELLS WHICH COULD DROP VIS TO LESS THAN ONE MILE AT TIMES. ACTIVITY WILL BEGIN DISSIPATING LATER IN THE AFTN AND INTO THE EVENING. MEFFER && .MARINE... WEAK SURFACE TROUGH DRAPED ALONG THE NEARSHORE WATERS FROM BAY ST. LOUIS ACROSS PLAQUEMINES PARISH AND SOUTH OF TERREBONNE BAY IS THE MAIN FOCUS OF SHOWER AND THUNDERSTORM ACTIVITY THIS MORNING. DUE TO ENVIRONMENT THATS CONDUCIVE FOR WATERSPOUTS IN PLACE...EXPECT SEVERAL TO DEVELOP ACROSS MARINE AREAS TODAY. OTHERWISE...LIGHT SOUTHEAST WINDS OF 5 TO 10 KNOTS BECOMING SW MID WEEK WILL LEND TO SEAS OF ONLY A FOOT OR 2. ISOLATED TO SCT TSRMS FOR THE REST OF THE PERIOD AFTER TODAY. MEFFER && .PRELIMINARY POINT TEMPS/POPS... MCB 88 71 94 72 / 60 20 20 10 BTR 89 74 94 75 / 70 30 30 10 ASD 89 72 93 74 / 70 30 20 10 MSY 89 75 92 77 / 80 30 30 10 GPT 89 73 92 75 / 70 20 20 20 PQL 89 71 93 71 / 70 20 10 20 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...NONE. GM...NONE. MS...NONE. GM...NONE. &&
Hazardous weather outlook, Jul 17, 7:10 PM CDT, 10 hours 25 minutes before
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</html>In the hours before
Special weather statement, Jul 18, 4:00 AM CDT, 1 hour 35 minutes before
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE NEW ORLEANS LA 400 AM CDT MON JUL 18 2011 LAZ040-050-058-060>064-066>070-072-MSZ080>082-181700- ST. TAMMANY-LIVINGSTON-ST. JOHN THE BAPTIST-ST. CHARLES- UPPER JEFFERSON-ORLEANS-UPPER PLAQUEMINES-UPPER ST. BERNARD- LOWER TERREBONNE-LOWER LAFOURCHE-LOWER JEFFERSON- LOWER PLAQUEMINES-LOWER ST. BERNARD-SOUTHERN TANGIPAHOA-HANCOCK- HARRISON-JACKSON- INCLUDING THE CITIES OF...SLIDELL...MANDEVILLE...COVINGTON... LACOMBE...DENHAM SPRINGS...WALKER...LAPLACE...RESERVE... DESTREHAN...NORCO...METAIRIE...KENNER...NEW ORLEANS... BELLE CHASSE...CHALMETTE...VIOLET...CHAUVIN...DULAC...MONTEGUT... GALLIANO...CUT OFF...GOLDEN MEADOW...PORT SULPHUR...EMPIRE... YSCLOSKEY...HAMMOND...PONCHATOULA...BAY ST. LOUIS...WAVELAND... DIAMONDHEAD...GULFPORT...BILOXI...PASCAGOULA...OCEAN SPRINGS... MOSS POINT...GAUTIER...ST. MARTIN 400 AM CDT MON JUL 18 2011 ...INCREASED WATERSPOUT AND ISOLATED HEAVY RAINFALL THREAT TODAY... CONDITIONS ACROSS THE AREA ARE CONDUCIVE FOR TWO MAIN THREATS TODAY. THE FIRST IS WATERSPOUTS. SEVERAL HAVE BEEN REPORTED OVER THE LAST WEEK IN LAKE PONTCHARTRAIN AS WELL AS OTHER NEAR SHORE MARINE AREAS. EXPECT THIS HIGHER THAN USUAL THREAT TO CONTINUE TODAY. BOATERS SHOULD BE ON ALERT AT ALL TIMES AND SEEK SAFE HARBOR IF A WATERSPOUT IS SPOTTED. THE SECOND THREAT IS HEAVY RAINFALL. THUNDERSTORMS MAY PRODUCE LOCALIZED FLOODING TODAY. RAINFALL RATES OF 3 TO 5 INCHES PER HOUR COULD OCCUR WITH THE MOST INTENSE STORMS. THIS HIGH INTENSITY OF RAIN COULD LEAD TO FLASH FLOODING AND MOTORISTS SHOULD AVOID DRIVING THROUGH WATER COVERED ROADWAYS. BOTH OF THESE HAZARDS WILL BEGIN TO DECREASE STARTING TUESDAY.
The office that day
Everything else NWS New Orleans, LA issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 18, 4:51 AM CDT | Special Marine Warning | LIX | 54 min | |
| Jul 18, 5:52 AM CDT | Special Marine Warning | LIX | 23 min | |
| Jul 18, 6:46 AM CDT | Flash Flood Warning | LIX | Jefferson, Orleans, Plaquemines, Saint Bernard | 3 hr |
| Jul 18, 9:16 AM CDT | Flash Flood Warning | LIX | Assumption, Lafourche, Terrebonne | 3 hr |
| Jul 18, 5:56 AM CDT | Tornado Warning | LIX | Harrison | 49 min |
| Jul 18, 7:09 AM CDT | Flash Flood Warning | LIX | Harrison | 3 hr |
| Jul 18, 8:22 AM CDT | River Flood Warning | LIX | Harrison | 27 hr |
| Jul 18, 9:10 AM CDT | Flash Flood Warning | LIX | Harrison, Jackson | 4 hr |
Nearby
Areal Flood Advisories in Louisiana, 2011Every areal flood advisory in 2011
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.