915 
 WTNT44 KNHC 290252
 TCDAT4
  
 HURRICANE ISAAC DISCUSSION NUMBER  32
 NWS NATIONAL HURRICANE CENTER MIAMI FL       AL092012
 1000 PM CDT TUE AUG 28 2012
  
 ISAAC PASSED OVER THE MISSISSIPPI RIVER DELTA IN EXTREME SOUTHEAST
 LOUISIANA AROUND 2345 UTC.  SINCE THAT TIME...THE CENTER HAS
 WOBBLED WESTWARD AND HAS MOVED BACK OVER WATER. A NORTHWESTWARD
 MOTION HAS RECENTLY RESUMED AND A SECOND LANDFALL SHOULD OCCUR
 LATER TONIGHT NEAR GRAND ISLE.  DATA FROM NOAA AND AIR FORCE
 RESERVE HURRICANE HUNTER AIRCRAFT INDICATE THAT THE MINIMUM
 PRESSURE HAS CONTINUED TO GRADUALLY FALL AND IS NOW 968 MB. THE AIR
 FORCE RESERVE AIRCRAFT HAS MEASURED A PEAK 850-MB FLIGHT-LEVEL WIND
 OF 96 KT AND BIAS-CORRECTED SFMR WINDS OF AROUND 65 KT.  BASED ON
 THESE DATA...THE INITIAL INTENSITY REMAINS 70 KT.  LITTLE CHANGE IN
 STRENGTH IS EXPECTED DURING THE NEXT 12 HOURS OR SO AS THE CENTER
 MOVES ACROSS THE BAYOUS OF SOUTHEASTERN LOUISIANA.  STEADY
 WEAKENING SHOULD COMMENCE LATER WEDNESDAY AS THE CENTER MOVES
 FARTHER INLAND.
  
 SMOOTHING THROUGH THE WOBBLES DURING THE PAST FEW HOURS...THE LONGER
 TERM MOTION ESTIMATE IS 310/7 KT.  ISAAC IS EXPECTED TO MOVE SLOWLY
 NORTHWESTWARD DURING THE NEXT 24 TO 36 HOURS AS A MID-LEVEL RIDGE TO
 THE NORTHWEST OF THE CYCLONE SLIDES EASTWARD.  AS THE RIDGE MOVES
 ACROSS THE OHIO VALLEY AND INTO THE MID-ATLANTIC REGION...THIS
 SHOULD CAUSE ISAAC TO TURN NORTH-NORTHWESTWARD AND NORTHWARD IN A
 COUPLE OF DAYS.  AFTER THAT TIME...THE CYCLONE IS EXPECTED TO TURN
 NORTHEASTWARD AS IT ENTERS THE MID-LATITUDE WESTERLY FLOW.  THE
 GLOBAL MODEL GUIDANCE HAS BEEN SHIFTING WESTWARD DURING THE PAST
 COUPLE OF RUNS...AND THE NHC FORECAST HAS BEEN ADJUSTED IN THAT
 DIRECTION.
  
 BECAUSE OF THE SLOW MOTION OF ISAAC...A PROLONGED PERIOD OF STRONG
 WINDS AND HEAVY RAINFALL ARE EXPECTED OVER A LARGE PORTION OF THE
 NORTHERN GULF COAST.  THE THREAT OF HEAVY RAINFALL AND FLOODING IS
 ALSO EXPECTED TO SPREAD INLAND OVER THE LOWER MISSISSIPPI VALLEY
 REGION DURING THE NEXT FEW DAYS.
  
 NATIONAL OCEAN SERVICE TIDE GAUGES INDICATE THAT STORM SURGE HEIGHTS
 OF 6 TO 10 FEET ARE OCCURRING ALONG PORTIONS OF THE COAST OF
 SOUTHEASTERN LOUISIANA AND MISSISSIPPI.  GIVEN THE LONG DURATION
 OF ONSHORE FLOW IN THESE AREAS...WATER LEVELS ARE EXPECTED TO REMAIN
 HIGH FOR THE NEXT 12 TO 24 HOURS.
 
  
 FORECAST POSITIONS AND MAX WINDS
  
 INIT  29/0300Z 29.0N  89.7W   70 KT  80 MPH
  12H  29/1200Z 29.6N  90.6W   65 KT  75 MPH...INLAND
  24H  30/0000Z 30.3N  91.4W   55 KT  65 MPH...INLAND
  36H  30/1200Z 31.5N  92.3W   35 KT  40 MPH...INLAND
  48H  31/0000Z 33.2N  93.2W   25 KT  30 MPH...INLAND
  72H  01/0000Z 37.0N  94.0W   20 KT  25 MPH...POST-TROP/REMNT LOW
  96H  02/0000Z 40.0N  91.5W   15 KT  15 MPH...POST-TROP/REMNT LOW
 120H  03/0000Z 41.5N  86.5W   15 KT  15 MPH...POST-TROP/REMNT LOW
  
 $$
 FORECASTER BROWN