870 
 WTNT44 KNHC 222031
 TCDAT4
 TROPICAL DEPRESSION FOUR DISCUSSION NUMBER   5
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042006
 500 PM EDT TUE AUG 22 2006
  
 DESPITE SOME INCREASE OF CONVECTION NEAR THE CENTER THIS
 AFTERNOON...THERE IS LIMITED BANDING AND DVORAK INTENSITY ESTIMATES
 FROM TAFB AND SAB REMAIN AT 30 KT. CONSEQUENTLY THE SYSTEM WILL NOT
 BE UPGRADED AT THIS TIME. HOWEVER...WITH CONVECTION ON THE INCREASE
 THE CLASSIFICATIONS SHOULD SUPPORT TROPICAL STORM STRENGTH VERY
 SOON. WHILE THE OUTFLOW PATTERN HAS BEEN IMPROVING TODAY AND THE
 SHEAR IS FAIRLY LOW...THE CYCLONE WILL BE MOVING OVER SLIGHTLY
 COOLER WATERS AND A MORE STABLE BOUNDARY LAYER FLOW...SO I AM
 ANTICIPATING ONLY SLOW DEVELOPMENT OVER THE NEXT COUPLE OF DAYS.
 AFTER THAT...WATERS WARM BUT SOME OF THE GLOBAL MODELS SUGGEST AN
 INCREASE IN SOUTHERLY SHEAR ASSOCIATED WITH AN UPPER-LEVEL LOW IN
 THE CENTRAL ATLANTIC. BOTH THE SHIPS AND GFDL MODELS HAVE BACKED
 OFF SLIGHTLY WITH THEIR INTENSITY FORECASTS AND THE OFFICIAL
 FORECAST IS ALSO NUDGED DOWN.
 
 THE INITIAL MOTION IS 300/16...OR ABOUT 15 DEGREES TO THE RIGHT OF
 THIS TIME YESTERDAY.  RECENT MICROWAVE PASSES SUGGEST A BETTER
 CO-LOCATION OF THE MID AND LOW-LEVEL CENTERS.  THERE HAS BEEN
 SIGNIFICANT CONVERGENCE IN HOW THE GLOBAL MODELS HANDLE THE
 DEPRESSION...WITH THE 12Z RUNS OF THE UKMET AND ECMWF NOW
 MAINTAINING THE SYSTEM AND SHIFTING THEIR TRACKS TO THE RIGHT. 
 THEY ARE NOW IN GOOD AGREEMENT WITH THE GFS AND ALSO WITH THE GFDL
 THROUGH ABOUT 72 HOURS.  THERE HAS BEEN LITTLE CHANGE TO THE
 SYNOPTIC SITUATION...WITH ALL THE GUIDANCE INDICATING AN EASTWARD
 SHIFT OF THE SUBTROPICAL RIDGE AND TROUGHING DEVELOPING OVER THE
 CENTRAL ATLANTIC.  THE OFFICIAL FORECAST HAS BEEN SHIFTED SLIGHTLY
 TO THE RIGHT OF THE PREVIOUS TRACK AND IS IN BEST AGREEMENT WITH
 THE GFS AND ECMWF.  
  
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      22/2100Z 14.5N  27.5W    30 KT
  12HR VT     23/0600Z 15.7N  29.7W    35 KT
  24HR VT     23/1800Z 17.2N  32.4W    40 KT
  36HR VT     24/0600Z 18.8N  35.2W    40 KT
  48HR VT     24/1800Z 20.1N  38.0W    45 KT
  72HR VT     25/1800Z 23.0N  44.0W    50 KT
  96HR VT     26/1800Z 27.0N  49.0W    55 KT
 120HR VT     27/1800Z 30.0N  53.0W    60 KT
  
 $$
 FORECASTER FRANKLIN