109 
 WTNT41 KNHC 290242
 TCDAT1
 TROPICAL DEPRESSION SIXTEEN DISCUSSION NUMBER   3
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL162010
 1100 PM EDT TUE SEP 28 2010
 
 TROPICAL DEPRESSION SIXTEEN CONTINUES TO HAVE A STRUCTURE MORE
 CHARACTERISTIC OF A WESTERN NORTH PACIFIC/NORTH INDIAN OCEAN
 MONSOON DEPRESSION.  SURFACE OBSERVATIONS CONTINUE TO INDICATE
 WINDS OF 20 KT OR LESS OVER AN AREA ENCOMPASSING 100 N MI IN
 DIAMETER FROM THE CENTER...AND THAT THE STRONGEST WINDS AND
 CONVECTION ARE 250-300 N MI AWAY FROM THE CENTER IN THE
 SOUTHEASTERN QUADRANT.  AN EARLIER AIR FORCE RESERVE HURRICANE
 HUNTER MISSION IN THIS AREA FOUND FLIGHT-LEVEL WINDS SUPPORTING AN
 INITIAL INTENSITY OF 30 KT.  SURFACE OBSERVATIONS INDICATE THAT THE
 CENTRAL PRESSURE IS NEAR 997 MB.
 
 THERE ARE MULTIPLE LOW-LEVEL CLOUD SWIRLS PRESENT...AND THE CENTER
 APPEARS TO RE-FORM FROM TIME TO TIME.  THE INITIAL MOTION OF 035/7
 IS THUS A BIT UNCERTAIN.  OTHER THAN THAT...THERE IS NO CHANGE IN
 THE FORECAST PHILOSOPHY FROM THE PREVIOUS ADVISORY...AND ONLY MINOR
 CHANGES TO THE FORECAST TRACK.  A COMBINATION OF A DEEP-LAYER
 TROUGH OVER THE SOUTHEASTERN UNITED STATES AND EASTERN GULF OF
 MEXICO AND A LOW/MID-LEVEL RIDGE OVER THE WESTERN ATLANTIC SHOULD
 STEER THE CYCLONE NORTH-NORTHEASTWARD WITH ACCELERATION FOR THE
 NEXT 12-24 HOURS...FOLLOWED BY A QUICK NORTHWARD MOTION.  THERE IS
 SOME SPREAD IN BOTH THE SPEED AND DIRECTION OF MOTION BY 48 HR. 
 THE GFS... GFDL...AND HWRF ARE MUCH FASTER AND TO THE LEFT OF THE
 REST OF THE GUIDANCE...WHILE THE NOGAPS...GFDN...AND GFS ENSEMBLE
 MEAN ARE SLOWER AND TO THE RIGHT.  THESE DIFFERENCES LIKELY RESULT
 FROM THE MODEL HANDLING OF THE DEPRESSION INTERACTING WITH A
 DEVELOPING BAROCLINIC LOW OVER THE EASTERN UNITED STATES.  THE NEW
 FORECAST TRACK IS DOWN THE MIDDLE OF THE GUIDANCE ENVELOPE CLOSE TO
 THE CONSENSUS MODELS.
 
 THE DEPRESSION IS CURRENTLY IN AN ENVIRONMENT OF 15 KT OF
 SOUTHWESTERLY VERTICAL WIND SHEAR...WHICH THE LARGE-SCALE MODELS
 FORECAST TO INCREASE DURING THE NEXT 12-24 HR.  THUS...NEITHER THE
 ENVIRONMENT NOR THE CURRENT STRUCTURE ARE CONDUCIVE FOR SIGNIFICANT
 STRENGTHENING.  THE INTENSITY FORECAST IS THE SAME AS IN THE
 PREVIOUS ADVISORY...WITH MODEST STRENGTHENING ALONG THE LINES OF
 THE SHIPS AND LGEM MODELS.  EXTRATROPICAL TRANSITION IS EXPECTED TO
 BEGIN IN ABOUT 24 HR OR SO AND BE COMPLETE BY 36-48 HR.  THE
 CYCLONE IS FORECAST TO BE ABSORBED BY THE EASTERN U. S. BAROCLINIC
 LOW AFTER 48 HR...AS FORECAST BY MOST OF THE DYNAMICAL GUIDANCE.
  
 UNLESS THE STRUCTURE CHANGES RADICALLY IN THE NEXT 12-24 HOURS...IT
 IS LIKELY THAT THERE WILL CONTINUE TO BE A LARGE AREA OF LIGHT
 WINDS NEAR THE CENTER.  THE STRONGEST WINDS SHOULD OCCUR IN AREAS
 WELL TO THE EAST OF THE FORECAST TRACK.
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      29/0300Z 21.9N  81.9W    30 KT
  12HR VT     29/1200Z 23.3N  81.2W    35 KT
  24HR VT     30/0000Z 26.3N  80.2W    40 KT
  36HR VT     30/1200Z 30.6N  79.3W    40 KT...POST-TROP/EXTRATROP
  48HR VT     01/0000Z 36.3N  78.0W    35 KT...POST-TROP/EXTRATROP
  72HR VT     02/0000Z...ABSORBED BY EXTRATROPICAL LOW
  
 $$
 FORECASTER BEVEN