137 
 WTNT43 KNHC 131439
 TCDAT3
 TROPICAL DEPRESSION EIGHT DISCUSSION NUMBER   5
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082006
 1100 AM EDT WED SEP 13 2006
  
 MORNING VISIBLE IMAGERY INDICATES THAT TROPICAL DEPRESSION EIGHT
 REMAINS POORLY ORGANIZED...WITH THE CIRCULATION ELONGATED
 WEST-SOUTHWEST TO EAST-NORTHEAST AND SEVERAL VORTICITY MAXIMA
 ROTATING AROUND THE MEAN CENTER.  SCATTERED CONVECTIVE CLUSTERS ARE
 PRESENT IN THE WESTERN SEMICIRCLE.  SATELLITE INTENSITY ESTIMATES
 ARE 30 KT FROM ALL AGENCIES...AND THAT REMAINS THE INITIAL
 INTENSITY.
 
 THE INITIAL MOTION IS 270/15.  THE DEPRESSION IS SOUTH OF A
 DEEP-LAYER RIDGE OVER THE EASTERN ATLANTIC...WHICH SHOULD KEEP THE
 SYSTEM MOVING GENERALLY WESTWARD FOR 24 HR OR SO.  AFTER THAT...THE
 LARGE-SCALE MODELS FORECAST THE CYCLONE TO GRADUALLY TURN
 WEST-NORTHWESTWARD AND THEN NORTHWESTWARD TOWARD A WEAKNESS IN THE
 RIDGE NORTHEAST OF THE LESSER ANTILLES.  ONE EXCEPTION TO THIS IS
 THE CANADIAN MODEL...WHICH IS A LEFT OUTLIER BRINGING THE CYCLONE
 TO JUST NORTHEAST OF THE LEEWARD ISLANDS BY 120 HR.  THE NEW
 FORECAST TRACK FOLLOWS THE MAJORITY OF THE GUIDANCE IN CALLING FOR
 A NORTHWESTWARD MOTION BY 120 HR.  THE NEW FORECAST TRACK IS A
 LITTLE TO THE LEFT OF THE MODEL CONSENSUS DUE TO A PAST TENDENCY OF
 THE LARGE-SCALE MODELS TO MOVE TROPICAL CYCLONES TOO FAR NORTH IN
 THIS SYNOPTIC PATTERN.
 
 THE CURRENT BROAD AND DISORGANIZED STRUCTURE SUGGESTS THAT
 SHORT-TERM INTENSIFICATION SHOULD BE SLOW.  THUS...THE INTENSITY
 FORECAST TAKES 24 HR TO BRING THE DEPRESSION TO TROPICAL STORM
 STRENGTH.  AFTER THAT...THE SYSTEM SHOULD STRENGTHEN AT A FASTER
 RATE IN A LIGHT VERTICAL SHEAR ENVIRONMENT...AND IT IS FORECAST TO
 BECOME A HURRICANE IN 72-96 HR.  THERE ARE TWO COMPLICATING FACTORS
 IN THE INTENSITY FORECAST.  THE FIRST IS DRY AIR PRESENT NORTH AND
 WEST OF THE CYCLONE.  HOW MUCH OF THIS AIR WILL BE ENTRAINED INTO
 THE SYSTEM IS UNCLEAR AT THIS TIME.  THE SECOND IS AN UPPER-LEVEL
 TROUGH FORECAST BY THE LARGE-SCALE MODELS TO THE NORTH OR NORTHEAST
 OF THE LESSER ANTILLES BY 120 HR.  WHILE THE MODELS AGREE THE
 TROUGH WILL EXIST...THEY DO NOT AGREE ON THE LOCATION OR ON THE
 POSSIBLE IMPACT TO THE CYCLONE.
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      13/1500Z 12.0N  28.5W    30 KT
  12HR VT     14/0000Z 12.2N  30.7W    30 KT
  24HR VT     14/1200Z 12.8N  34.0W    35 KT
  36HR VT     15/0000Z 13.8N  37.0W    40 KT
  48HR VT     15/1200Z 15.1N  39.6W    50 KT
  72HR VT     16/1200Z 18.0N  43.5W    60 KT
  96HR VT     17/1200Z 20.0N  46.5W    70 KT
 120HR VT     18/1200Z 22.0N  49.5W    80 KT
  
 $$
 FORECASTER BEVEN