Tornado Warning 30, NWS New Orleans, LA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
427 AM CDT MON OCT 16 2006

.DISCUSSION...NUMEROUS WEATHER CONCERNS ARE ON TAP EARLY IN THE
FORECAST PERIOD. WIDESPREAD RAIN OCCURRING ACROSS MUCH OF THE
FORECAST AREA EARLY THIS MORNING WITH EMBEDDED SUPERCELLS. THE
SUPERCELLS OCCURRING TO THE NORTH OF A WARM FRONT BISECTING THE
AREA APPEAR TO BE ELEVATED WHILE CELLS ALONG AND SOUTH OF THE
BOUNDARY ARE SURFACE BASED AND HAVE PRODUCED TWO OR THREE TORNADOS
THAT HAVE RESULTED IN SOME DAMAGE ALREADY THIS MORNING. THE THREAT
OF SEVERE WEATHER IS EXPECTED TO CONTINUE THROUGH THE DAY WITH THE
GREATEST THREAT OF SHORT LIVED TORNADOES DURING THE MORNING AND
EARLY AFTERNOON HOURS WHEN VERY IMPRESSIVE HELICITY VALUES AND
SHEAR WILL BE THE GREATEST. ALL OF THIS IS OCCURRING IN ADVANCE
OF AN UPPER LOW/SHORT WAVE OVER NEW MEXICO THAT WAS ADVANCING
TOWARD THE SOUTHERN PLAINS AND LOWER MISSISSIPPI VALLEY. AS IT
TRAVERSES EAST NORTHEAST MODELS FORECAST THIS FEATURE TO DEVELOP
INTO AN OPEN WAVE AND GRADUALLY WEAKEN. IN THE MEANTIME...A STRONG
LOW LEVEL JET HAS DEVELOPED IN ADVANCE OF THIS SYSTEM ACROSS THE
LOWER MISSISSIPPI VALLEY AND WAS ADVECTING VERY RICH MOISTURE
LADEN AIR NORTHWARD. THIS FEATURE WILL SHIFT GRADUALLY NORTHEAST
ACROSS THE REGION THROUGH THE DAY AND INTO TONIGHT. A FAVORABLY
POSITIONED UPPER LEVEL JET WILL ALSO AID THUNDERSTORM DEVELOPMENT.
PERSISTENT STRONG EAST TO SOUTHEAST FLOW HAS CAUSED TIDES TO RISE TO
TWO TO THREE FEET ABOVE NORMAL ALONG SOME COASTAL AREAS WITH MINOR
COASTAL FLOODING ALREADY BEING REPORTED IN HANCOCK COUNTY. SINCE
THESE STRONG WINDS WILL CONTINUE INTO TONIGHT...THE COASTAL FLOOD
WATCH HAS BEEN UPGRADED TO A COASTAL FLOOD WARNING. THE
POSSIBILITY OF HEAVY RAINFALL THROUGH TONIGHT ACROSS THE NORTHWEST
ZONES WILL NECESSITATE THE CONTINUATION OF THE FLASH FLOOD WATCH
IN THAT AREA. SMALL CRAFT ADVISORY CONDITIONS ARE EXPECTED TO
CONTINUE INTO TUESDAY MORNING BEFORE WINDS AND WAVES DIMINISH.

THE GFS AND NAM DIFFER IN THEIR SOLUTIONS FOR TUESDAY AND
WEDNESDAY THE NAM BEING MUCH WETTER THAN THE GFS WHICH BRINGS
DRIER AIR INTO THE REGION FASTER. PLAN TO KEEP SOME POPS IN THE
FORECAST THROUGH TUESDAY...BUT WILL GO WITH THE DRY GFS FOR
TUESDAY NIGHT AND WEDNESDAY. THE NEXT CHANCE FOR RAIN COMES
THURSDAY AS ANOTHER COLD FRONT PUSHES ACROSS THE AREA AS A BROAD
UPPER TROUGH SHIFTS EAST ACROSS THE CONUS. ANOTHER COLD FRONT AND
A CHANCE FOR RAIN WILL AFFECT THE AREA SATURDAY NIGHT AND SUNDAY
MORNING AS AN UPPER TROUGH DEEPENS OVER THE CENTRAL AND EASTERN U.S.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  80  72  85  68 / 100 100  40  10
BTR  82  74  86  69 / 100 100  50  10
MSY  84  76  86  72 / 100  90  50  10
GPT  80  74  84  71 /  90  80  50  10

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...FLASH FLOOD WATCH THROUGH TUESDAY MORNING FOR LAZ034-LAZ035-
     LAZ036-LAZ037-LAZ038-LAZ046-LAZ047-LAZ048-LAZ049-LAZ050.

     COASTAL FLOOD WARNING THROUGH TUESDAY MORNING FOR LAZ066-
     LAZ067-LAZ068-LAZ069-LAZ070-LAZ064-LAZ063-LAZ062-LAZ061-
     LAZ060-LAZ058-LAZ050-LAZ038-LAZ040.

MS...FLASH FLOOD WATCH THROUGH TUESDAY MORNING FOR MSZ068-
     MSZ069-MSZ070.

     COASTAL FLOOD WARNING THROUGH TUESDAY MORNING FOR MSZ080-
     MSZ081-MSZ082-

GM...SMALL CRAFT ADVISORY UNTIL 1 PM CDT TUESDAY FOR GMZ550-GMZ555-
     GMZ570-GMZ575.

     SMALL CRAFT ADVISORY UNTIL 7 AM CDT TUESDAY FOR GMZ530.

&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1031 PM CDT SUN OCT 15 2006

LAZ034>040-046>050-056>070-MSZ068>071-077-080>082-170345-
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-
1031 PM CDT SUN OCT 15 2006

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

.DAY ONE...TONIGHT

.SEVERE THUNDERSTORMS...
STRONG WIND SHEAR IN THE LOWER LEVELS OF THE ATMOSPHERE ALONG A
STRONG WARM FRONT MOVING NORTH OUT OF THE GULF OF MEXICO WILL BE
CONDUCIVE TO SEVERE THUNDERSTORM DEVELOPMENT. THERE IS A SLIGHT
RISK OF SEVERE THUNDERSTORMS LATER TONIGHT AND MONDAY MORNING. THE
PRIMARY THREAT WILL BE ISOLATED TORNADOES DEVELOPING FROM
STRONGLY ROTATING STORMS MOVING OUT OF THE COASTAL AREAS. DAMAGING
WINDS AND PERIODS OF VERY HEAVY RAINFALL CAN ALSO OCCUR PRIMARILY
AFTER 4 AM MONDAY.

.FLOODING...
A FLOOD WATCH IS IN EFFECT FOR THE EAST-CENTRAL AND SOUTH-
CENTRAL PARISHES OF LOUISIANA...INCLUDING THE GREATER BATON ROUGE
AREA. THE GREATEST THREAT OF FLOODING RAINS WILL BE GENERALLY
AFTER 3 AM MONDAY...CONTINUING INTO MONDAY EVENING.

.MARINE HAZARDS...
A COASTAL FLOOD WATCH IS IN EFFECT UNTIL TUESDAY
MORNING FOR THE MISSISSIPPI AND SOUTHEAST LOUISIANA COAST.
ABNORMALLY HIGH TIDES OF 2 FEET ABOVE NORMAL CAN BE EXPECTED. THIS
MAY CAUSE SOME FLOODING OF LOW LYING COASTAL AREAS...PARTICULARLY
DURING THE DAILY HIGH TIDE PERIOD DURING THE MORNING HOURS.

A SMALL CRAFT ADVISORY IS IN EFFECT FOR ROUGH SEAS AND STRONG EAST
WINDS.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

WIDESPREAD RAIN AND THUNDERSTORMS WILL CONTINUE MONDAY INTO TUESDAY
ACROSS THE AREA...AS A SLOW MOVING AREA OF LOW PRESSURE PASSES
THROUGH THE TENNESSEE VALLEY. A SLIGHT RISK OF SEVERE
THUNDERSTORMS WILL CONTINUE MONDAY INTO MONDAY NIGHT. THE MAIN
THREAT FROM ANY THUNDERSTORMS WILL BE VERY HEAVY
RAINFALL...FREQUENT LIGHTNING...STRONG WINDS...AND ISOLATED
TORNADOES. RAINFALL AMOUNTS OF 2 TO 3 INCHES ARE POSSIBLE WITH THE
HEAVIEST THUNDERSTORMS...WITH TOTAL RAINFALL AMOUNTS OF 4 TO 6
INCHES POSSIBLE ACROSS THE REGION BY TUESDAY MORNING. LOCALIZED
FLOODING OF LOW LYING AREAS AND STREETS WILL BE POSSIBLE.

STRONG SOUTHEAST WINDS OF 20 TO 30 KNOTS OVER THE COASTAL WATERS
WILL CONTINUE TO PROMPT SMALL CRAFT CONDITIONS THROUGH TUESDAY.
THESE WINDS WILL ALSO KEEP TIDE LEVELS HIGH ON SOUTH AND EAST
FACING SHORES WITH TIDES RUNNING UP TO 2 FEET ABOVE NORMAL. SOME
FLOODING OF COASTAL AREAS OUTSIDE OF HURRICANE PROTECTION LEVEES
WILL CONTINUE TO BE POSSIBLE.

SCATTERED THUNDERSTORMS ARE EXPECTED WEDNESDAY AND THURSDAY AS A
COLD FRONT SWEEPS THROUGH THE AREA. A FEW STRONG TO SEVERE
THUNDERSTORMS ARE POSSIBLE ON THURSDAY NEAR THE FRONT.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS BEING REQUESTED FOR LATE TONIGHT AND
MONDAY...MAINLY IN THE LOUISIANA COASTAL PARISHES BEFORE DAYBREAK
AND IN THE NEW ORLEANS AND BATON ROUGE METRO AREAS FROM DAYBREAK
THROUGH MONDAY. LAW ENFORCEMENT AGENCIES AND FIRST RESPONDERS
SHOULD PLAN ACCORDINGLY FOR AN EXTENDED PERIOD OF ACTIVE WEATHER.
PLEASE NOTIFY THE NATIONAL WEATHER SERVICE OFFICE IN SLIDELL
PROMPTLY IF SEVERE WEATHER OCCURS IN YOUR AREA.

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