349 
 WTPZ43 KNHC 261449
 TCDEP3
  
 TROPICAL STORM MIRIAM DISCUSSION NUMBER  19
 NWS NATIONAL HURRICANE CENTER MIAMI FL       EP132012
 800 AM PDT WED SEP 26 2012
  
 THE CLOUD PATTERN OF MIRIAM HAS BECOME POORLY ORGANIZED. THE CENTRAL
 DENSE OVERCAST HAS DEGENERATED INTO A LONG BAND WRAPPING AROUND THE
 WESTERN SIDE OF THE CIRCULATION. SATELLITE DATA ALSO INDICATE AN
 INCREASING SEPARATION BETWEEN THE LOW- TO MID-LEVEL CENTERS DUE TO
 20-25 KT OF SOUTHWESTERLY SHEAR ASSOCIATED WITH A SHORTWAVE TROUGH
 ROTATING AROUND THE NORTHWESTERN SIDE OF THE STORM. SATELLITE
 INTENSITY ESTIMATES RANGE FROM 55-65 KT...AND GIVEN THE
 DETERIORATING SATELLITE APPEARANCE...THE INITIAL INTENSITY IS
 LOWERED TO 55 KT. FURTHER GRADUAL WEAKENING IS LIKELY AS MIRIAM
 ENCOUNTERS CONTINUED MODERATE OR STRONG SOUTHWESTERLY SHEAR...
 GRADUALLY DECREASING SSTS...AND A DRIER AND MORE STABLE AIR MASS.
 THE NHC INTENSITY FORECAST IS AN UPDATE OF THE PREVIOUS ONE AND IS
 CLOSE TO THE SHIPS AND LGEM OUTPUT.
  
 THE LONG-TERM INITIAL MOTION ESTIMATE IS 330/05...BUT RECENT
 MICROWAVE DATA SUGGEST THAT THE SHORT-TERM MOTION COULD BE FARTHER
 TO THE RIGHT. AS THE PREVIOUSLY MENTIONED SHORTWAVE TROUGH DIGS TO
 THE WEST OF MIRIAM DURING THE NEXT DAY OR SO...THE CYCLONE SHOULD
 MAINTAIN A SLOW NORTH-NORTHWESTWARD MOTION. A BEND OF THE TRACK
 TOWARD THE NORTHWEST IS FORECAST WHEN THE SHORTWAVE REACHES A
 POSITION TO THE SOUTH OF STORM IN 24-36 HOURS. IF MIRIAM DECOUPLES
 SOONER THAN EXPECTED...THE LOW-LEVEL CENTER COULD MOVE MORE TO THE
 LEFT THAN FORECAST. THE NHC TRACK FORECAST IS NEAR OR SLIGHTLY TO
 THE LEFT OF THE PREVIOUS ONE AND IS CLOSE TO THE FSU
 SUPERENSENSEMBLE AND THE MULTI-MODEL CONSENSUS THROUGH 24 HOURS AND
 THEN CLOSE TO THE GFS AFTER THAT.
  
   
 FORECAST POSITIONS AND MAX WINDS
  
 INIT  26/1500Z 20.0N 115.7W   55 KT  65 MPH
  12H  27/0000Z 20.9N 115.9W   45 KT  50 MPH
  24H  27/1200Z 22.0N 116.3W   40 KT  45 MPH
  36H  28/0000Z 22.6N 116.7W   35 KT  40 MPH
  48H  28/1200Z 23.0N 117.0W   30 KT  35 MPH...POST-TROP/REMNT LOW
  72H  29/1200Z 23.2N 117.4W   25 KT  30 MPH...POST-TROP/REMNT LOW
  96H  30/1200Z 23.4N 117.9W   20 KT  25 MPH...POST-TROP/REMNT LOW
 120H  01/1200Z...DISSIPATED
  
 $$
 FORECASTER KIMBERLAIN