489 
 WTNT44 KNHC 261451
 TCDAT4
  
 TROPICAL STORM NADINE DISCUSSION NUMBER  56
 NWS NATIONAL HURRICANE CENTER MIAMI FL       AL142012
 1100 AM AST WED SEP 26 2012
  
 NADINE HAS BECOME BETTER ORGANIZED THIS MORNING.  VISIBLE IMAGERY
 SHOWS INCREASING CONVECTIVE BANDING IN THE NORTHERN SEMICIRCLE...
 ALONG WITH DEVELOPING ANTICYCLONIC CIRRUS OUTFLOW.  A RECENT ASCAT
 OVERPASS SHOWED SEVERAL 40-KT VECTORS IN THE NORTHWEST QUADRANT...
 AND SUGGESTS THAT THE RADIUS OF MAXIMUM WIND HAS CONTRACTED TO
 ABOUT 40 N MI.  THE INITIAL INTENSITY IS INCREASED TO 45 KT...BASED
 ON THE ASCAT DATA.
  
 THE STORM HAS BEEN MOVING SOUTHWARD FOR THE PAST SEVERAL HOURS...
 WITH THE INITIAL MOTION 180/3.  THE TRACK GUIDANCE IS IN GOOD
 AGREEMENT FOR THE NEXT 48-72 HR...FORECASTING NADINE TO TURN
 SOUTHWESTWARD...WESTWARD...AND THEN NORTHWESTWARD AROUND A
 DEEP-LAYER RIDGE MOVING EASTWARD ACROSS THE NORTHEASTERN ATLANTIC. 
 THE GUIDANCE BECOMES DIVERGENT AFTER 72 HR DUE TO DIFFERENCES IN
 THE FORECAST FORWARD SPEED OF NADINE AND WHETHER THE STORM WILL
 RECURVE INTO THE WESTERLIES AHEAD OF AN APPROACHING MID-/
 UPPER-LEVEL TROUGH.  THE CANADIAN MODEL SHOWS THE TROUGH
 ACCELERATING NADINE TO THE NORTHEAST...WHILE THE NOGAPS...GFDL...
 AND HWRF SHOW THE CYCLONE STALLING NEAR THE 120 HR POINT.  THE
 UKMET AND ECMWF SHOW THE TROUGH BYPASSING NADINE TO THE NORTH...
 WITH RIDGING BEHIND THE TROUGH CAUSING THE CYCLONE TO AGAIN MOVE
 SOUTHWARD.  THE GFS...IN A SIGNIFICANT SHIFT FROM ITS PREVIOUS
 FORECAST...IS NOW MORE IN LINE WITH THE UKMET AND ECMWF.  GIVEN THE
 UNCERTAINTY...THE TRACK FORECAST CALLS FOR A SLOW MOTION AFTER THE
 96 HR POINT.  THE NEW TRACK IS SIMILAR TO THE PREVIOUS TRACK AND IS
 NEAR THE CENTER OF THE TRACK GUIDANCE ENVELOPE.
 
 NADINE IS MOVING OVER INCREASING SEA SURFACE TEMPERATURES.  THE
 SHIPS MODEL AND ANALYSES FROM CIMSS SUGGEST THE CYCLONE IS IN A
 LIGHT SHEAR ENVIRONMENT...ALTHOUGH WATER VAPOR IMAGERY SUGGESTS THE
 POSSIBILITY THAT SOME NORTHERLY UPPER-LEVEL FLOW IS UNDERCUTTING
 THE OUTFLOW.  THE INTENSITY GUIDANCE FORECASTS A RELATIVELY
 FAVORABLE ENVIRONMENT TO CONTINUE FOR ABOUT 36 HR...AND THE
 INTENSITY FORECAST SHOWS SLOW INTENSIFICATION DURING THIS TIME. 
 AFTER 36 HR...INCREASING WESTERLY SHEAR AND A MOTION OVER COOLER
 WATERS SHOULD HALT INTENSIFICATION AND CAUSE A GRADUAL WEAKENING. 
 THE INTENSITY FORECAST IS SIMILAR TO THE SHIPS AND THE INTENSITY
 CONSENSUS THROUGH 48 HR...AND IS LOWER THAN THOSE MODELS AFTER
 THAT.
  
 FORECAST POSITIONS AND MAX WINDS
  
 INIT  26/1500Z 30.6N  30.3W   45 KT  50 MPH
  12H  27/0000Z 29.8N  30.9W   45 KT  50 MPH
  24H  27/1200Z 28.9N  32.0W   45 KT  50 MPH
  36H  28/0000Z 28.7N  33.4W   50 KT  60 MPH
  48H  28/1200Z 29.4N  34.5W   50 KT  60 MPH
  72H  29/1200Z 32.0N  36.0W   50 KT  60 MPH
  96H  30/1200Z 35.0N  36.5W   45 KT  50 MPH
 120H  01/1200Z 36.0N  37.0W   45 KT  50 MPH
  
 $$
 FORECASTER BEVEN