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| #531969 (Received by flhurricane at: 10:47 AM 05.Aug.2012) TCDAT5 TROPICAL STORM ERNESTO DISCUSSION NUMBER 16 NWS NATIONAL HURRICANE CENTER MIAMI FL AL052012 1100 AM EDT SUN AUG 05 2012 AN AIR FORCE HURRICANE HUNTER AIRCRAFT HAS BEEN INVESTIGATING ERNESTO THIS MORNING AND FOUND THAT THE LOW-LEVEL CENTER IS LESS WELL-DEFINED THAN IT WAS YESTERDAY. ALSO...VISIBLE SATELLITE IMAGERY SHOWS THAT THE CENTER IS DISPLACED TO THE WEST OF MOST OF THE DEEP CONVECTION. PRECIPITABLE WATER IMAGERY AND GLOBAL MODEL ANALYSES INDICATE DRY LOW- TO MID-LEVEL AIR WEST AND SOUTH OF THE TROPICAL CYCLONE...AND THIS HAS PROBABLY BEEN DISRUPTING THE SYSTEM. ASSUMING THAT ERNESTO IS ABLE TO OVERCOME THIS UNFAVORABLE THERMODYNAMIC FACTOR...SOME STRENGTHENING IS POSSIBLE WHEN THE FORWARD SPEED SLOWS IN A DAY OR SO. THE OFFICIAL FORECAST IS CLOSE TO THE INTENSITY MODEL CONSENSUS BUT CONTINUES TO BE BELOW THE STATISTICAL-DYNAMICAL LGEM/SHIPS GUIDANCE. THE LATTER HAS BEEN SHOWING SOMEWHAT OF A HIGH BIAS FOR THIS SYSTEM. THE GFS MODEL CONTINUES TO SHOW NO STRENGTHENING. THE STORM CONTINUES TO MOVE SWIFTLY TOWARD THE WEST...AT A FORWARD SPEED OF AT LEAST 20 KT. GLOBAL MODELS INDICATE THAT THE MID-LEVEL RIDGE TO THE NORTH OF THE TROPICAL CYCLONE WILL WEAKEN IN A DAY OR TWO...WHICH SHOULD CAUSE THE FORWARD MOTION TO DECELERATE. MOST OF THE TRACK GUIDANCE...AND THE OFFICIAL FORECAST...SHOWS A TURN TOWARD THE WEST-NORTHWEST IN A DAY OR SO. A MID-TROPOSPHERIC TROUGH OVER THE EASTERN U.S. IS EXPECTED TO WEAKEN THE RIDGE A LITTLE MORE OVER THE GULF OF MEXICO IN A FEW DAYS. ALTHOUGH THE GFDL AND U.K. MET MODEL FORECASTS SHOW A MOTION TOWARD THE NORTHWEST GULF COAST IN THE LATTER PART OF THE FORECAST PERIOD...THE TROUGH IS NOT EXPECTED TO WEAKEN THE RIDGE ENOUGH TO CAUSE A SIGNIFICANT NORTHWARD TURN. THIS IS CONFIRMED BY THE GFS AND ECMWF RUNS...AND IN FACT THE LATEST GFS FORECAST BARELY BRINGS THE TROPICAL CYCLONE INTO THE GULF. THE OFFICIAL FORECAST IS A LITTLE SOUTH OF THE PREVIOUS ONE...AND CLOSE TO THE ECMWF TRACK. FORECAST POSITIONS AND MAX WINDS INIT 05/1500Z 15.0N 77.1W 45 KT 50 MPH 12H 06/0000Z 15.0N 79.4W 45 KT 50 MPH 24H 06/1200Z 15.4N 81.8W 45 KT 50 MPH 36H 07/0000Z 15.9N 83.6W 50 KT 60 MPH 48H 07/1200Z 16.5N 85.3W 55 KT 65 MPH 72H 08/1200Z 18.0N 89.0W 55 KT 65 MPH...INLAND 96H 09/1200Z 20.0N 92.5W 50 KT 60 MPH 120H 10/1200Z 21.5N 96.0W 65 KT 75 MPH $$ FORECASTER PASCH/ROBERTS |
