Tornado Warning 40, NWS New Orleans, LA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
958 PM CST MON NOV 15 2010

.UPDATE...

.SOUNDING DISCUSSION...

NO PROBLEMS WITH THE FLIGHT THIS EVENING. A MOIST AND UNSTABLE
EVENING WITH A PW OF 1.56 INCHES AND AN LI OF -3.3. A LIGHT
SOUTHERLY FLOW IN PLACE IN THE LOWEST LEVELS WITH A STRONG
SOUTHWESTERLY FLOW IN PLACE ALOFT. A VERY STRONG WEST...SOUTHWESTERLY
JET AT 220 MILLIBARS WITH WINDS AS HIGH AS 136 KNOTS.

&&

.PREV DISCUSSION... /ISSUED 319 PM CST MON NOV 15 2010/

..A FEW STRONG TO SEVERE STORMS POSSIBLE TONIGHT...

SHORT TERM...BNDRY HAS NOT MOVED MUCH DURING THE DAY AND THE NWRN
HALF OF THE CWA HAS MOSTLY REMAINED DRY. THAT SAID WITH THE
EXCEPTION OF ONE BREAK IN THE CLOUDS TEMPORARILY ALLOWING A FEW
LOCATIONS TO WARM UP INTO THE LOWER 70S MOSTLY OVC SKIES HAS KEPT
MUCH OF THE AREA NORTH OF THE BNDRY IN THE 60S AND EVEN UPPER 50S
THROUGH 20Z IN ISLTD LOCATIONS OF SWRN MS. COASTAL AREAS OF SERN LA
WERE IN THE LOWER TO MID 70S MUCH OF THE DAY.

BIGGEST FORECAST CONCERN IS STRONG TO SVR WEATHER TONIGHT. MUCH OF
THE FOCUS IS ON THE BNDRY DRAPED FROM THE NWRN GULF ACROSS SERN
LA/COASTAL MS/SRN AL. AS A DISTURBANCE MOVES THROUGH THE SRN PLAINS
AND INTO THE LOWER MS VALLEY IT SHOULD HELP KICK THINGS OFF. A SFC
LOW/WAVE WILL START TO DEVELOP ALONG THE BNDRY AND BEGIN TO MOVE TO
THE NE ACROSS OUR CWA INTO SRN MS LATE THIS EVN AND EARLY MRNG HRS.
THIS SFC LOW WILL CONTINUE TO PUSH TO THE NE INTO THE TN VALLEY AND
SHOULD DRIVE THE COLD FRONT COMPLETELY THROUGH THE CWA BY SUNRISE.
SHRA AND TSRA WILL DEVELOP OUT AHEAD OF THIS NEXT IMPULSE AND ALONG
THE FRONT. THIS SHOULD MOSTLY AFFECT THE SERN 2/3RDS OF THE CWA WITH
MOST OF THE ACTIVITY LIKELY OCCURRING BETWEEN 02Z AND 09Z. BEFORE
TAPERING OFF TO MORE OF A LIGHT POST FRONTAL SHRA EVENT.

AS FOR THE SVR ASPECT...WE ARE UNDER A SLIGHT RISK OF SVR STORMS AS
THE IMPULSE COMES ACROSS THE REGION TONIGHT. AS THE SFC LOW DEVELOPS
AND DEEPENS THE KINEMATIC FIELD WILL BECOME MORE FAVORABLE FOR THE
DEVELOPMENT OF SEVERE STORMS. IN ADDITION WITH THE APPROACH OF THE
DISTURBANCE IS GOING TO INCREASE THE FORCING. AGAIN THE BIG ISSUE
FOR THE DEVELOPMENT OF SVR WEATHER WILL BE THE THERMODYNAMIC FIELD.
INSTABILITY IS GOING TO REALLY BE LIMITED. AHEAD OF THE FRONT WARM
MOIST AIR WILL BE IN PLACE AND COULD ALLOW FOR MLCAPE VALUES TO
APPROACH 500 J/KG. THIS ALONG WITH THE FORCING COULD VERY WELL BE
ENOUGH TO GET ONE OR TWO LOW TOPPED SUPERCELLS CAPABLE OF PRODUCING
DAMAGING WINDS AND EVEN A TORNADO OR TWO. ONE POSITIVE COULD BE THAT
THE WINDS MAY BECOME UNIDIRECTIONAL QUICKLY ACROSS THE CWA IF THE
SFC LOW REMAINS BROAD AND DOESN'T DEEPEN UNTIL LATE IN THE MORNING
AND FURTHER TO OUR N. THIS WOULD TEND TO LEAD TO A GREATER WIND
THREAT AND DECREASE THE TORNADIC RISK. AGAIN THE BIGGEST QUESTION
WILL BE WHERE AND WHEN THE SFC WAVE/LOW DEVELOPS.

BY SUNRISE TOMORROW THINGS SHOULD BE QUICKLY QUIETING DOWN AS THE
COLD FRONT PUSHES FURTHER TO THE EAST. RAIN AND EVENTUALLY CLOUDS
SHOULD START TO COME TO AN END FROM NW TO SE. LIGHT SPRINKLES MAY
LINGER ON INTO THE AFTN HRS ACROSS NRN PORTIONS OF THE CWA BUT
OVERALL MUCH OF THE RAIN SHOULD BE OVER WELL BEFORE NOON TOMORROW.
CLOUDS WILL START TO CLEAR OUT AND BY TOMORROW NIGHT CLOUDS SHOULD
REALLY BE OUT OF THE AREA WITH A SUNNY COOL DAY IN STORE ON WED.

LONG TERM...NO CHANGES MADE TO THE EXTENDED PORTION OF THE FCST AS
THINGS START QUIET. A REINFORCING COLD FRONT SHOULD PUSH THROUGH
HERE LATE WED NIGHT AND REALLY HELP TO COOL THINGS OFF ONCE AGAIN.
MEDIUM RANGE MDLS SEEM TO BE IN DECENT AGREEMENT WITH BOTH THE GFS
AND ECMWF SHOWING THE SAME BASIC PATTERN SETTING UP FOR US. WITH
THAT I HAVE MADE VERY LITTLE CHANGES TO THE EXTENDED FCST AND WILL
APPEND THE PREVIOUS LONG TERM DISCUSSION. /CAB/

PREVIOUS LONG TERM DISCUSSION...ANOTHER SHORTWAVE TROUGH WILL PASS
THROUGH THE MID MISSISSIPPI VALLEY LATE WEDNESDAY AND WEDNESDAY
NIGHT. THIS WILL BRING A REINFORCING COLD FRONT THROUGH THE FORECAST
AREA LATE WEDNESDAY NIGHT. THERE WILL BE VERY LITTLE MOISTURE
AVAILABLE TO WORK WITH THIS FRONT...SO AM NOT INCLUDING ANY MENTION
OF RAIN. HIGH PRESSURE WILL REBUILD OVER THE AREA THURSDAY INTO
FRIDAY...THEN THE HIGH WILL MOVE EAST FRIDAY NIGHT THROUGH EARLY
NEXT WEEK. A GENERAL ZONAL TO SOUTHWEST FLOW PATTERN IN THE
MID/UPPER LEVELS WILL PREVAIL...AND TEMPERATURES ARE LIKELY TO RISE
ABOVE NORMAL BY SUNDAY AS HIGH PRESSURE BUILDS AND HEIGHTS RISE OVER
THE GULF OF MEXICO. 22/TD

AVIATION...
STALLED FRONTAL BOUNDARY IS KEEPING A STEADY STREAM OF MODERATE RAIN
JUST SOUTH OF BOTH LOCATIONS. IT WON/T TAKE MUCH RETROGRESSION OF THE
THIS FRONT BACK NORTH TO BEGIN IMPACTING MSY/HSA/GPT. A SECOND ROUND
OF SHOWERS MAY TRACK FURTHER INLAND LATER THIS EVENING. ABUNDANT
MOISTURE AND LIGHT WINDS OVERNIGHT WILL LIKELY LEAD TO MVFR VIS AT
MOST TERMINALS. WINDS WILL SHIFT TO NW AND RAIN TO BE CLEARING OUT
TOMORROW AFTN.

MEFFER

MARINE...
GRADIENT ALONG STALLED FRONTAL BOUNDARY HAS LEAD TO STRONG SWRLY
WINDS. RESULTING SEAS HAVE INCREASED TO 6 TO 8 FEET OVER THE OUTER
WATERS. EXPECT THESE CONDITIONS TO PERSIST THROUGH TUESDAY. WINDS
AND SEAS WILL RELAX FOR A TIME TUESDAY AFTER LOW MOVES AWAY FROM THE
AREA...THEN INCREASE AGAIN TUESDAY NIGHT AS THE COLD AIR REACHES THE
GULF. WILL PROBABLY NEED SOME HEADLINES AT THAT POINT AS WELL.
ANOTHER COLD FRONT WILL MOVE THROUGH THE AREA ON THURSDAY WITH
ANOTHER INCREASE IN WINDS. THE REMAINDER OF THE WEEKEND WILL BE
GENERALLY LIGHT EAST WINDS AND SEAS OF 2 FEET AND LESS.

MEFFER

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  55  63  36  66 /  70  10  10   0
BTR  58  66  41  69 /  60  10  10   0
ASD  60  71  41  67 /  80  10  10   0
MSY  62  71  46  66 /  70  10  10   0
GPT  61  72  42  66 /  90  20  10   0
PQL  61  75  42  66 /  90  20  10   0

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
GM...SMALL CRAFT ADVISORY UNTIL 9 AM TUESDAY FOR THE FOLLOWING ZONES:
     BRETON SOUND...CHANDELEUR SOUND...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 FROM 20 TO 60 NM...COASTAL WATERS FROM
     PASCAGOULA MS TO STAKE ISLAND LA OUT 20 NM...COASTAL WATERS
     FROM STAKE ISLAND LA TO THE SOUTHWEST PASS OF THE
     MISSISSIPPI RIVER FROM 20 TO 60 NM...COASTAL WATERS FROM
     THE PORT FOURCHON TO LOWER ATCHAFALAYA RIVER FROM 20 TO 60
     NM...COASTAL WATERS FROM THE PORT FOURCHON TO LOWER
     ATCHAFALAYA RIVER OUT 20 NM...COASTAL WATERS FROM THE
     SOUTHWEST PASS OF THE MISSISSIPPI RIVER TO PORT FOURCHON
     FROM 20 TO 60 NM...COASTAL WATERS FROM THE SOUTHWEST PASS
     OF THE MISSISSIPPI RIVER TO PORT FOURCHON OUT 20 NM...AND
     MISSISSIPPI SOUND.

MS...NONE.
GM...SMALL CRAFT ADVISORY UNTIL 9 AM TUESDAY FOR THE FOLLOWING ZONES:
     BRETON SOUND...CHANDELEUR SOUND...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 FROM 20 TO 60 NM...COASTAL WATERS FROM
     PASCAGOULA MS TO STAKE ISLAND LA OUT 20 NM...COASTAL WATERS
     FROM STAKE ISLAND LA TO THE SOUTHWEST PASS OF THE
     MISSISSIPPI RIVER FROM 20 TO 60 NM...COASTAL WATERS FROM
     THE PORT FOURCHON TO LOWER ATCHAFALAYA RIVER FROM 20 TO 60
     NM...COASTAL WATERS FROM THE PORT FOURCHON TO LOWER
     ATCHAFALAYA RIVER OUT 20 NM...COASTAL WATERS FROM THE
     SOUTHWEST PASS OF THE MISSISSIPPI RIVER TO PORT FOURCHON
     FROM 20 TO 60 NM...COASTAL WATERS FROM THE SOUTHWEST PASS
     OF THE MISSISSIPPI RIVER TO PORT FOURCHON OUT 20 NM...AND
     MISSISSIPPI SOUND.

&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE NEW ORLEANS LA
600 PM CST MON NOV 15 2010

GMZ530-532-534-536-538-550-552-555-557-570-572-575-577-LAZ034>040-
046>050-056>070-MSZ068>071-077-080>082-161745-
LAKE PONTCHARTRAIN AND LAKE MAUREPAS-MISSISSIPPI SOUND-
LAKE BORGNE-CHANDELEUR SOUND-BRETON SOUND-
COASTAL WATERS FROM THE 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 THE 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-
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-
600 PM CST MON NOV 15 2010

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

.DAY ONE...TONIGHT

THUNDERSTORMS...
THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS TONIGHT EAST OF A
LINE FROM DONALDSONVILLE TO BOGALUSA AS AN UPPER AIR DISTURBANCE
MOVES INTO THE LOWER MISSISSIPPI VALLEY AND AN AREA OF LOW PRESSURE
MOVES ACROSS SOUTHEAST LOUISIANA AND SOUTH MISSISSIPPI. THE MAIN
THREATS FROM ANY SEVERE STORMS WILL BE DAMAGING WIND GUSTS
AND ISOLATED TORNADOES.

MARINE...
A SMALL CRAFT ADVISORY IS IN EFFECT FOR THE GULF COASTAL WATERS FOR
WINDS OF 20 TO 25 KNOTS AND ROUGH SEAS.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

A SMALL CRAFT ADVISORY WILL BE IN EFFECT FOR THE GULF COASTAL WATERS
THROUGH 9 AM TUESDAY FOR WINDS OF 20 TO 25 KNOTS AND ROUGH SEAS.

OTHERWISE...NO HAZARDOUS WEATHER IS EXPECTED DURING THE PERIOD.

.SPOTTER INFORMATION STATEMENT...
THE ACTIVATION OF STORM SPOTTERS...HAM RADIO OPERATORS...AND
EMERGENCY MANAGEMENT PERSONNEL IN SUPPORT OF SEVERE WEATHER
OPERATIONS MAY BE NEEDED TONIGHT.

LAZ059-065>067-160200-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
629 PM CST MON NOV 15 2010

...STRONG THUNDERSTORM MOVING NORTHEAST OUT OF THE GULF THAT WILL
AFFECT TERREBONNE AND LAFOURCHE PARISHES...

AT 618 PM CST...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A
STRONG THUNDERSTORM 40 MILES SOUTHWEST OF HOUMA...OR ABOUT 25 MILES
WEST OF TAMBOUR BAY BUOY...MOVING NORTHEAST AT 40 MPH.

THE STRONG THUNDERSTORM WILL AFFECT AREAS IN AND AROUND
COCODRIE...DULAC...HOUMA...CHAUVIN...MONTEGUT...RACELAND...LOCKPORT
...MATHEWS...LEEVILLE...GALLIANO...GOLDEN MEADOW...LAROSE AND CUT OFF

THE PRIMARY THREATS FROM THIS STORM ARE FREQUENT LIGHTNING AND WIND
GUSTS TO NEAR 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.

LAZ069-160400-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
904 PM CST MON NOV 15 2010

...STRONG THUNDERSTORM MOVING NORTHEAST AFFECTING PLAQUEMINES
PARISH...

AT 900 PM CST...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A
STRONG THUNDERSTORM 11 MILES SOUTHWEST OF PORT SULPHUR...MOVING
NORTHEAST AT 20 MPH.

THE STRONG THUNDERSTORM WILL AFFECT AREAS IN AND AROUND...POINTE A LA
HACHE...PORT SULPHUR AND EMPIRE

THE PRIMARY THREAT FROM THIS STORM IS WIND GUSTS TO NEAR 45
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.