Severe Thunderstorm Warning 169, NWS New Orleans, LA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
344 PM CDT MON JUL 11 2011

.SHORT TERM...
TYPICAL SEA BREEZE SHOWERS CONTINUE TO DEVELOP AND DISSIPATE MAINLY
ACROSS COASTAL PARISHES OF LOUISIANA. A FEW OF THESE MAY PRODUCE
GUSTY WINDS AND BRIEF HEAVY DOWNPOURS BUT FOR THE MOST PART WILL BE
FAIRLY DOCILE. THE MAIN CONCERN WILL BE THE MORE ROBUST CONVECTION
THAT HAS DEVELOPED OVER SOUTHERN MISSISSIPPI AND ALABAMA. THIS
ACTIVITY HAS BEEN SLOWLY PROGRESSING SOUTHWESTWARD. BOTH HRRR AND
NCEP/WRF MODELS INDICATE THAT A LINE WILL DEVELOP AND PROGRESS SWWD
ACROSS THE CWA THIS EVENING. BASED ON GOOD INITIALIZATION AND
CONTINUED ACCURACY OVER THE LAST FEW HOURS DOES GIVE SOME CONFIDENCE
IN THIS PLAYING OUT. REALLY NOT EXPECTING MUCH IN THE WAY OF SEVERE
WEATHER WITH THIS...HOWEVER...A WIDE SWATH OF SUBSTANTIAL AND MUCH
NEEDED RAINFALL COULD OCCUR. THE CONVECTION SHOULD DISSIPATE FAIRLY
RAPIDLY AS IT NEARS BTR AND NEW.

.LONG TERM...
UPPER LEVEL RIDGE WILL GRADUALLY SHIFT BACK WEST BY MID WEEK AND
THEN TOWARDS THE MID MISS VALLEY BY THE WEEKEND. THIS IS GREAT NEWS
IN TERMS OF INCREASED RAIN CHANCES THROUGH THE WEEK. EXPECT ANYWHERE
FROM 40 TO 60 PCT CHANCE THROUGH THE PERIOD. THE NOT SO GOOD NEWS IS
THAT IF YOU ARE NOT UNDER A SHOWER OR STORM...EXPECT HOT TEMPS WITH
HEAT INDICES NEAR 105 DEGREES.

MEFFER
&&

.AVIATION...
CONTINUING TO MONITOR A DEVELOPING MCS MOVING AROUND THE PERIPHERY
OF THE RIDGE OUT OF OF ALABAMA THIS AFTERNOON. HIGH RESOLUTION
MODELS CONTINUE TO INDICATE THIS AREA OF MULTICELLULAR CONVECTION
CONSOLIDATING INTO A QLCS STRUCTURE THROUGH THE EARLY EVENING.
STRONG UPPER IMPULSE IN THE NE AND NC GULF OF MEXICO WAS SPREADING A
LARGE ANVIL CANOPY DOWNSTREAM TO INHIBIT INLAND CONVECTION A
BIT...BUT THIS INFLUENCE WILL LIKELY WEAKEN IN TIME. WILL MAINTAIN
TEMPO CONVECTION GROUPS FOR EXPECTED ORGANIZED CONVECTION MAINLY AT
KGPT...KPQL...KHSA...KASD THROUGH ABOUT 02Z. OTHER LOCATIONS MAY SEE
CONVECTION AS WELL BUT DIFFICULT TO DETERMINE HOW MUCH THE UPPER
CANOPY WILL LIMIT THINGS FARTHER SOUTH AND WEST. MOST ACTIVITY
SHOULD DISSIPATE BY 05Z WITH VFR CONDITIONS THEREAFTER AS AIRMASS
GETS A THOROUGH WORKOVER.  24/RR

&&

.MARINE...
SURFACE RIDGE WILL REMAIN PARKED OVER THE SERN GULF THROUGH THIS
WEEK AND THEN SHIFT NORTHWARD OVER THE WEEKEND. THIS WILL LEND TO
FAIRLY LIGHT WINDS AND GENERALLY SOUTHWEST DEPENDING ON THE TIME
PERIOD. WINDS WILL MOSTLY REMAIN ONSHORE BUT WITH SUCH A WEAK
PATTERN IN PLACE CLOSE TO THE SHORE WINDS WILL VARY FROM ONSHORE
DURING THE AFTN AND EARLY EVN TO BECOMING MORE PARALLEL TO SHORE AND
POSSIBLY SLIGHTLY OFFSHORE DURING THE EARLY TO MID MORNING HRS.
EXPECT THAT NOCTURNAL INCREASE IN THE WINDS OVER THE WATERS TO OCCUR
BUT WINDS WILL BACK DOWN AROUND 15Z. SEAS/WAVES WILL BE A NON ISSUE
LIKELY AROUND 1-2 FT. AS FOR TIDES...TIDAL RANGES WILL CONTINUE TO
INCREASE A TAD FOR THE NEXT FEW DAYS BUT NO ISSUES EXPECTED THX TO
THE LIGHT ONSHORE FLOW.

CAB/MEFFER
&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  75  95  74  95 /  20  40  30  50
BTR  77  95  77  95 /  20  40  20  50
ASD  76  94  76  93 /  30  40  30  50
MSY  78  93  78  92 /  20  40  30  50
GPT  77  93  77  93 /  30  50  30  50
PQL  76  96  76  94 /  30  50  30  50

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
GM...NONE.
MS...NONE.
GM...NONE.
&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE NEW ORLEANS LA
718 PM CDT MON JUL 11 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>082-130030-
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-
718 PM CDT MON JUL 11 2011

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

.DAY ONE...TONIGHT

AN UPPER LEVEL DISTURBANCE MOVING INTO SOUTHERN MISSISSIPPI WILL
CONTINUE TO PRODUCE THUNDERSTORMS OVER PORTIONS OF COASTAL AND
SOUTHWEST MISSISSIPPI AS A WELL AS PORTIONS OF SOUTHEAST LOUISIANA
MAINLY NORTH OF INTERSTATE 12 AND EAST OF INTERSTATE 55. THESE
THUNDERSTORMS WILL ALSO PUSH OFFSHORE INTO THE SOUNDS AND COASTAL
WATERS. THESE THUNDERSTORMS ARE EXPECTED TO REMAIN WEAK...PRODUCING
OCCASIONAL LIGHTNING STRIKES AND WINDS GUSTING TO 35 MPH.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

ISOLATED TO SCATTERED THUNDERSTORMS WILL BE POSSIBLE EACH DAY
THROUGH SUNDAY. ORGANIZED SEVERE WEATHER IS NOT ANTICIPATED.
HOWEVER...A FEW STRONG TO SEVERE THUNDERSTORMS WILL BE POSSIBLE
MAINLY DURING THE AFTERNOON HOURS. THE MAIN THREATS WILL BE
DAMAGING WINDS...FREQUENT LIGHTNING...AND BRIEF HEAVY RAIN.
WATERSPOUT ACTIVITY WILL BE POSSIBLE OVER MARINE AREAS.

HEAT INDEX VALUES SHOULD REMAIN AROUND 105 DEGREES EACH AFTERNOON
THROUGH MUCH OF THE WEEK OUTSIDE OF RAIN AREAS. THOSE WITH
OUTDOOR PLANS SHOULD TAKE CAUTION TO REMAIN HYDRATED AND KNOW
WHEN TO GO INDOORS TO COOL OFF. NEVER LEAVE CHILDREN OR PETS
UNATTENDED IN VEHICLES EVEN FOR A FEW MINUTES. REMEMBER...BEAT
THE HEAT...CHECK THE BACK SEAT.

MINOR FLOODING WILL CONTINUE ALONG THE ATCHAFALAYA RIVER AT
MORGAN CITY. REFER TO THE LATEST RIVER FLOOD STATEMENT FOR
DETAILS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

32

MSZ082-112230-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
449 PM CDT MON JUL 11 2011

...CLUSTER OF STRONG THUNDERSTORMS MOVING SOUTHWEST AFFECTING JACKSON
COUNTY...

AT 447 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
CLUSTER OF STRONG THUNDERSTORMS 13 MILES NORTH OF ESCATAWPA...OR
ABOUT 4 MILES NORTHEAST OF WADE...MOVING SOUTHWEST AT 15 MPH.

THE CLUSTER OF STRONG THUNDERSTORMS WILL AFFECT AREAS IN AND
AROUND...WADE...ESCATAWPA AND VANCLEAVE

THE PRIMARY THREATS FROM THESE STORMS ARE FREQUENT LIGHTNING AND 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 THESE STORMS HAVE PASSED.

FREQUENT LIGHTNING IS OCCURRING WITH THESE STORMS. IF OUTDOORS...STAY
AWAY FROM ISOLATED HIGH OBJECTS SUCH AS TREES. MOVE INDOORS IF
POSSIBLE. WHEN INDOORS...STAY AWAY FROM WINDOWS AND DOORS AND AVOID
USING TELEPHONES UNLESS IT IS AN EMERGENCY. TRY TO UNPLUG UNNECESSARY
ELECTRICAL APPLIANCES BEFORE THE THUNDERSTORM APPROACHES.

MSZ081-120000-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
557 PM CDT MON JUL 11 2011

...LINE OF STRONG THUNDERSTORMS MOVING SOUTHWEST AFFECTING HARRISON
COUNTY...

AT 552 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
LINE OF STRONG THUNDERSTORMS...ALONG A LINE EXTENDING FROM 13 MILES
SOUTHWEST OF WIGGINS TO 16 MILES NORTH OF ST. MARTIN...MOVING
SOUTHWEST AT 5 MPH.

THE LINE OF STRONG THUNDERSTORMS WILL AFFECT AREAS IN AND AROUND...
SAUCIER

THE PRIMARY THREATS FROM THESE STORMS ARE FREQUENT LIGHTNING AND 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 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.

LAZ039-071-120145-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
743 PM CDT MON JUL 11 2011

...STRONG THUNDERSTORM MOVING WEST AFFECTING WASHINGTON PARISH...
TANGIPAHOA PARISH...

AT 740 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A
STRONG THUNDERSTORM 11 MILES NORTHWEST OF FRANKLINTON...OR ABOUT OVER
MOUNT HERMAN...MOVING WEST AT 5 MPH.

THE STRONG THUNDERSTORM WILL AFFECT AREAS IN AND AROUND...TANGIPAHOA
AND KENTWOOD

THE PRIMARY THREATS FROM THIS STORM ARE FREQUENT LIGHTNING AND 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.

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.

LAZ037-071-120215-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
811 PM CDT MON JUL 11 2011

...STRONG THUNDERSTORM MOVING WEST AFFECTING ST. HELENA PARISH...
TANGIPAHOA PARISH...

AT 809 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A
STRONG THUNDERSTORM 13 MILES NORTHEAST OF GREENSBURG...OR ABOUT OVER
KENTWOOD...MOVING WEST AT 10 MPH.

THE STRONG THUNDERSTORM WILL AFFECT AREAS IN AND AROUND...KENTWOOD...
TANGIPAHOA...GREENSBURG...EASLEYVILLE AND DARLINGTON

THE PRIMARY THREATS FROM THIS STORM ARE FREQUENT LIGHTNING...PEA TO
DIME SIZE HAIL...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 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.

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.