866 
 WTNT44 KNHC 270832
 TCDAT4
  
 TROPICAL STORM DORIAN DISCUSSION NUMBER  13
 NWS NATIONAL HURRICANE CENTER MIAMI FL       AL042013
 500 AM AST SAT JUL 27 2013
 
 DISORGANIZED CONVECTION HAS DEVELOPED NEAR THE CENTER OF DORIAN
 DURING THE PAST SEVERAL HOURS.  HOWEVER...WATER VAPOR IMAGERY SHOWS
 WIDESPREAD MID-/UPPER-LEVEL DRY AIR NEAR THE CYCLONE...WHICH
 SUGGESTS THIS CONVECTION COULD BE SHORT-LIVED.  THE INITIAL
 INTENSITY IS KEPT AT 35 KT BASED ON A SATELLITE INTENSITY ESTIMATE
 FROM TAFB AND EARLIER ASCAT DATA.  IT SHOULD BE NOTED THAT RECENT
 OSCAT DATA SUGGESTS THE POSSIBILITY THAT DORIAN NO LONGER HAS A
 CLOSED CIRCULATION.  
  
 THE INITIAL MOTION IS 275/19.  A STRONG LOW-/MID-LEVEL RIDGE NORTH
 OF DORIAN IS EXPECTED TO STEER THE CYCLONE QUICKLY WESTWARD FOR THE
 NEXT 72 HR.  THE TRACK GUIDANCE IS IN GOOD AGREEMENT WITH THIS
 SCENARIO...AND THE NEW TRACK FORECAST IS AN UPDATE OF THE PREVIOUS
 FORECAST.
  
 DORIAN IS FORECAST TO EXPERIENCE 15-20 KT OF VERTICAL WIND SHEAR
 DURING THE FORECAST PERIOD...AS WELL AS MOVE THROUGH A DRY
 MID-/UPPER-LEVEL AIR MASS.  THIS COMBINATION SHOULD CAUSE
 ADDITIONAL WEAKENING...WITH THE CYCLONE DEGENERATING TO A REMNANT
 LOW BY 36 HR.  AN ALTERNATIVE SCENARIO IS THAT THE SYSTEM COULD
 DEGENERATE TO A TROPICAL WAVE AT ANY TIME DURING THE NEXT 72 HR...
 AND THUS DISSIPATE EARLIER THAN CURRENTLY FORECAST.  UPPER-LEVEL
 WINDS IN THE AREA WEST OF THE FORECAST POINT OF DISSIPATION ARE NOT
 EXPECTED TO BE CONDUCIVE FOR RE-GENERATION AT THIS TIME.
  
 FORECAST POSITIONS AND MAX WINDS
  
 INIT  27/0900Z 18.2N  50.0W   35 KT  40 MPH
  12H  27/1800Z 18.6N  53.1W   30 KT  35 MPH
  24H  28/0600Z 19.2N  57.2W   30 KT  35 MPH
  36H  28/1800Z 19.8N  61.1W   25 KT  30 MPH...POST-TROP/REMNT LOW
  48H  29/0600Z 20.4N  64.7W   25 KT  30 MPH...POST-TROP/REMNT LOW
  72H  30/0600Z 21.0N  71.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
  96H  31/0600Z...DISSIPATED
  
 $$
 FORECASTER BEVEN