000 WTNT45 KNHC 060255 TCDAT5 TROPICAL STORM ERNESTO DISCUSSION NUMBER 18 NWS NATIONAL HURRICANE CENTER MIAMI FL AL052012 1100 PM EDT SUN AUG 05 2012 A BURST OF DEEP CONVECTION WITH CLOUD TOPS COLDER THAN -85C HAS DEVELOPED OVER THE PREVIOUSLY EXPOSED LOW-LEVEL CIRCULATION CENTER. HOWEVER...DATA FROM AN AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT INDICATE THAT THIS HAS NOT YET TRANSLATED INTO A STRENGTHENING TREND DESPITE THE SURFACE PRESSURE HAVING DECREASED TO ABOUT 1003 MB. THE STRONGEST 850 MB FLIGHT-LEVEL WIND REPORTED WAS 42 KT AND THE HIGHEST ADJUSTED-SFMR SURFACE WIND HAS BEEN AROUND 44 KT. BASED ON THIS INFORMATION...THE INITIAL INTENSITY IS MAINTAINED AT 45 KT...WHICH COULD BE GENEROUS. ERNESTO HAS CONTINUED TO DECELERATE AND THE INITIAL MOTION ESTIMATE IS NOW 270/13 KT. THE DECOUPLED MID- AND UPPER-LEVEL VORTEX HAS DISPLACED THE DEEP CONVECTION TO THE SOUTH SIDE OF THE LOW-LEVEL VORTEX...WHICH HAS RESULTED IN A SLIGHT JOG TO THE WEST-SOUTHWEST. HOWEVER...THIS IS EXPECTED TO BE A TEMPORARY MOTION AND ERNESTO SHOULD TURN TOWARD THE WEST-NORTHWEST WITHIN 12-24 HOURS...AND CONTINUE THAT MOTION FOR THE NEXT 48 HOURS...AFTER WHICH A TURN TOWARD THE WEST IS EXPECTED. OTHERWISE...THERE IS NO SIGNIFICANT CHANGE TO THE PREVIOUS TRACK FORECAST OR REASONING. THE OFFICIAL FORECAST TRACK IS SIMILAR TO THE PREVIOUS ADVISORY TRACK AND LIES CLOSE TO THE CONSENSUS MODELS TCVA AND TV15. THE GFS AND ECMWF MODELS HAVE DONE A SUPERB JOB IN FORECASTING THE RECENT SHORT-TERM WOBBLE TO THE WEST-SOUTHWEST OWING TO THE NORTHERLY SHEAR CREATED BY THE MID-LEVEL VORTEX BEING DISPLACED MORE THAN 60 NMI TO THE EAST OF THE LOW-LEVEL CENTER. THOSE MODELS ARE ALSO FORECASTING THE LOW-LEVEL AND MID-/UPPER-LEVEL CIRCULATIONS TO RE-COUPLE AND BECOME VERTICALLY ALIGNED AGAIN IN ABOUT 24 HOURS OR SO...WHICH SHOULD ALLOW FOR MORE SIGNIFICANT STRENGTHENING TO OCCUR. UNTIL THAT TIME...HOWEVER...ERNESTO IS EXPECTED TO STRENGTHEN LITTLE. THE OFFICIAL INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS ADVISORY AND FOLLOWS THE TREND OF THE INTENSITY CONSENSUS MODEL IV15 UNTIL LANDFALL IN ABOUT 48 HOURS...AND FOLLOWS THE DECAY-SHIPS MODEL AFTER THAT. FORECAST POSITIONS AND MAX WINDS INIT 06/0300Z 15.0N 79.7W 45 KT 50 MPH 12H 06/1200Z 15.3N 81.3W 50 KT 60 MPH 24H 07/0000Z 16.1N 83.3W 55 KT 65 MPH 36H 07/1200Z 17.1N 85.1W 60 KT 70 MPH 48H 08/0000Z 17.9N 87.5W 65 KT 75 MPH 72H 09/0000Z 19.0N 91.4W 35 KT 40 MPH...INLAND 96H 10/0000Z 20.0N 95.2W 50 KT 60 MPH...OVER WATER 120H 11/0000Z 20.5N 98.5W 55 KT 65 MPH...INLAND $$ FORECASTER STEWART