Severe Thunderstorm Warning 69, NWS New Orleans, LA

AREA FORECAST DISCUSSION...CORRECTION TO ADVISORY SECTION
NATIONAL WEATHER SERVICE NEW ORLEANS/BATON ROUGE LA
315 PM CDT MON APR 7 2003

...SEVERE THUNDERSTORM AND FLOOD POTENTIAL WILL CONTINUE...
...TODAYS SEVERE THUNDERSTORM OUTBREAK IS LIKELY TO BE THE WORST
   THIS CALENDAR YEAR...

STRONG TO SEVERE THUNDERSTORMS HAVE CONTINUED TO DEVELOP ALONG A
SOUTHWARD PROPAGATING OUTFLOW BOUNDARY WHICH NOW EXTENDS FROM NEAR
PICAYUNE TO LAKE PONTCHARTRAIN TO NEAR MORGAN CITY. THE SLIDELL
AIRPORT RECORDED A WIND GUST TO 60 MPH AT 249 PM. STATIONARY FRONTAL
BOUNDARY...WHICH IS VOID OF DEEP CONVECTION...EXTENDS FARTHER NORTH
ACROSS SOUTHWEST MS. NUMEROUS SUPERCELLS HAVE DEVELOPED ALONG THE
OUTFLOW BOUNDARY. THE SUPERCELLS HAVE PRODUCED NUMEROUS REPORTS OF
LARGE HAIL THIS MORNING INTO EARLY THIS AFTERNOON WITH DAMAGING WIND
GUST REPORTS COMING IN THIS AFTERNOON WITH DAYTIME HEATING AND THE
ADVECTION OF STRONGER MID LEVEL WINDS. MESOCYCLONE AND TORNADO
VORTEX SIGNATURES ON RADAR HAVE BEEN IMPRESSIVE AT TIMES...BUT THERE
HAVE BEEN NO CONFIRMED REPORTS OF TORNADOES. WITH THE SOUTHWARD
PROPAGATION OF THE OUTFLOW BOUNDARY AND THE 30 KNOT MOVEMENT OF
INDIVIDUAL CELLS...THERE HAVE BEEN NO REPORTS OF FLASH FLOODING AS
OF YET.

THE MAIN FORECAST PROBLEMS WILL CONTINUE TO BE THE MOVEMENT OF THE
OUTFLOW BOUNDARY AND WHETHER CONVECTION WILL REFOCUS FARTHER NORTH
NEAR THE SURFACE FRONT. THIS IS NOT A HIGH CONFIDENCE FORECAST...SO
WILL COMPROMISE AND KEEP THE HEAVIEST RAIN FROM ROUGHLY 30 MILES
SOUTH TO ABOUT 80 MILES NORTH OF THE CURRENT LOCATION OF THE OUTFLOW
BOUNDARY THROUGH TONIGHT. BECAUSE OF THE POTENTIAL FOR BOUNDARY
STALLING AND THE NUMEROUS OCCURRENCES OF SEVERE WEATHER...WILL
MAINTAIN THE FLOOD WATCH AND SEVERE WORDING IN THE ZONES
TONIGHT...EXCEPT WILL REISSUE THE FLOOD WATCH TO EXPAND THE AREA
SOUTH TO INCLUDE METRO NEW ORLEANS AN THE MS GULF COAST. EXPECT
RAINFALL AMOUNTS OF 1 TO 3 INCHES WITH LOCAL AMOUNTS UP TO 5 INCHES.

THE COLD FRONT SHOULD MOVE THROUGH THE MCB-BTR CORRIDOR LATE
TONIGHT...AND THE REMAINDER OF THE FORECAST AREA TUESDAY MORNING.
THE ETA AND NGM HOLD ON TO POST-FRONTAL RAIN LONGER THAN THE GFS
WITH THE NGM KEEPING POPS INTO WEDNESDAY WHILE THE GFS ENDS THE RAIN
SHORTLY AFTER FRONTAL PASSAGE ON TUESDAY AFTERNOON. WILL GO WITH THE
GFS SOLUTION FOR CONTINUITY. WRAP-AROUND PRECIP SHOULD ACCOMPANY THE
UPPER LOW AS IT MOVES SOUTHEAST THROUGH THE SOUTHEAST CONUS ON
WEDNESDAY AND WEDNESDAY NIGHT...BUT THIS SHOULD BE NORTHEAST OF THE
FORECAST AREA. MUCH COLDER AIR WILL SWEEP INTO THE REGION BEHIND THE
FRONT WITH LOW TEMPERATURES POSSIBLY FLIRTING WITH THE FREEZING MARK
AROUND MCCOMB LATE WEDNESDAY NIGHT. TEMPERATURES WILL MODERATE AND
IT WILL REMAIN DRY LATE IN THE WEEK AND INTO THE WEEKEND.

MCB 61/70/42/58 9610  BTR 62/70/44/58 +610
MSY 67/73/50/59 9810  GPT 66/73/46/61 9810

.NEW...SMALL CRAFT ADVISORY KPQL TO THE ATCHAFALAYA RIVER AND OUT 60
       60 NM.
LA...FLOOD WATCH LAZ034>040-046>050-056>065.
MS...FLOOD WATCH MSZ068>071-077-080>082.

22

LAZ034>040-046>050-056>070-MSZ068>071-077-080>082-080000-

HAZARDOUS WEATHER OUTLOOK...CORRECTION TO DAY ONE
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1130 AM CDT MON APR 7 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST LOUISIANA AND
EXTREME SOUTHWEST AND COASTAL MISSISSIPPI.

.DAY ONE...TODAY AND TONIGHT

SEVERE THUNDERSTORMS...
THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THROUGH TONIGHT
ACROSS ALL OF SOUTHEAST LOUISIANA AND SOUTH MISSISSIPPI. LARGE HAIL
AND DAMAGING WIND GUSTS WILL BE THE PRIMARY THREATS...HOWEVER...AN
ISOLATED TORNADO IS POSSIBLE. A VERY MOIST...WARM...AND UNSTABLE
AIRMASS...COMBINED WITH A STALLED SURFACE BOUNDARY AND NUMEROUS
UPPER LEVEL DISTURBANCES...WILL CONTINUE TO CAUSE SCATTERED TO
NUMEROUS THUNDERSTORMS TODAY AND TONIGHT.

HEAVY RAINFALL AND FLOODING...
THUNDERSTORMS WILL HAVE THE POTENTIAL TO REPEAT OVER THE SAME AREAS
THROUGH TONIGHT...MAINLY ACROSS AREAS OF SOUTHEAST LOUISIANA NORTH
AND WEST OF LAKE PONTCHARTRAIN INCLUDING SOUTHWEST MISSISSIPPI AND
PEARL RIVER COUNTY. RAINFALL AMOUNTS IN THESE AREAS WILL RANGE FROM
1 TO 3 INCHES WITH LOCALLY HIGHER AMOUNTS UP TO AROUND 5 INCHES
POSSIBLE THROUGH EARLY TUESDAY MORNING. THE HEAVY RAIN WILL RESULT
IN THE THREAT OF FLOODING OF SMALL STREAMS AND URBAN AREAS ALONG
WITH FLASH FLOODING OF LOCALIZED AREAS. THE HEAVY RAIN WILL ALSO
CAUSE NUMEROUS RIVERS TO RISE TO NEAR OR ABOVE FLOOD STAGE OVER THE
NEXT SEVERAL DAYS.

AREAS SOUTH OF LAKE PONTCHARTRAIN AND ALONG THE MISSISSIPPI COAST
SHOULD RECEIVE LESS RAINFALL AND A RESULTANT LOWER THREAT OF
FLOODING THROUGH TONIGHT.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

THERE IS SLIGHT RISK OF SEVERE THUNDERSTORMS ON TUESDAY...MAINLY
DURING THE MORNING HOURS...ACROSS AREAS SOUTH OF LAKE PONTCHARTRAIN
AND EAST OF INTERSTATE 59. LOCALLY HEAVY RAINFALL IS ALSO POSSIBLE.
A COLD FRONT WILL PUSH THROUGH COASTAL SECTIONS OF SOUTHEAST
LOUISIANA AND MISSISSIPPI BY AFTERNOON.

NO HAZARDOUS WEATHER IS EXPECTED TUESDAY AFTERNOON THROUGH SUNDAY.

.SPOTTER INFORMATION STATEMENT...

THE ACTIVATION OF STORM SPOTTERS...HAM RADIO OPERATORS AND EMERGENCY
MANAGEMENT PERSONNEL...IN SUPPORT OF SEVERE WEATHER OPERATIONS...IS
REQUESTED AT THIS TIME.