000 WTNT45 KNHC 031454 TCDAT5 TROPICAL STORM ERNESTO DISCUSSION NUMBER 8 NWS NATIONAL HURRICANE CENTER MIAMI FL AL052012 1100 AM AST FRI AUG 03 2012 DATA FROM A RECONNAISSANCE PLANE AND RADAR FROM MARTINIQUE SHOWED THE SMALL BUT WELL-DEFINED CENTER OF ERNESTO MOVED WESTWARD JUST SOUTH OF OR OVER ST. LUCIA EARLY THIS MORNING. BASED ON THE AIRCRAFT AND SURFACE OBSERVATIONS...THE INITIAL INTENSITY IS SET AT 45 KNOTS. THESE WINDS ARE CONFINED TO A SMALL AREA NORTH OF THE CENTER. FAST-MOVING TROPICAL CYCLONES TYPICALLY DO NOT STRENGTHEN MUCH AND IN FACT...LATEST SATELLITE IMAGES INDICATE LITTLE CHANGE IN THE STRUCTURE OF THE CYCLONE. ERNESTO IS MOVING TOWARD THE WEST OR 275 DEGREES AT 18 KNOTS EMBEDDED WITHIN A FAST EASTERLY FLOW SOUTH OF THE SUBTROPICAL RIDGE. THIS STEERING PATTERN SHOULD KEEP THE CYCLONE ON A GENERAL WESTWARD TRACK FOR THE NEXT 2 TO 3 DAYS. BY THE TIME ERNESTO REACHES THE WESTERN CARIBBEAN...THE STEERING FLOW IS EXPECTED TO WEAKEN AND ERNESTO IS FORECAST TO SLOW DOWN. THE COMBINATION OF LOW SHEAR AND HIGH UPPER-OCEAN HEAT CONTENT IN THE WESTERN CARIBBEAN SEA WOULD FAVOR SOME INTENSIFICATION...AND ERNESTO IS FORECAST TO BECOME A HURRICANE IN THE NORTHWESTERN CARIBBEAN SEA. THE OFFICIAL FORECAST FOLLOWS THE INTENSITY CONSENSUS...BUT ONE SHOULD NOTE THAT BOTH THE SHIPS AND LGEM INTENSITY MODELS ARE FORECASTING A STRONGER HURRICANE. MOST OF THE TRACK GUIDANCE IS IN PRETTY GOOD AGREEMENT THAT ERNESTO WILL BE RACING WESTWARD ACROSS THE EASTERN AND CENTRAL CARIBBEAN DURING THE NEXT 2 TO 3 DAYS. AFTER THAT...TRACK MODELS DIVERGE CONSIDERABLY AND SOME MODELS KEEP ERNESTO ON A MORE WESTWARD TRACK...WHILE ANOTHER GROUP TURN THE CYCLONE MORE TO THE NORTHWEST...DEPENDING UPON HOW THE MODELS DEPICT THE STRENGTH OF RIDGE TO THE NORTH. NEVERTHELESS...ALL INDICATIONS ARE THAT ERNESTO WILL BE MOVING ACROSS THE NORTHWESTERN CARIBBEAN SEA IN 4 TO 5 DAYS. FORECAST POSITIONS AND MAX WINDS INIT 03/1500Z 13.7N 62.3W 45 KT 50 MPH 12H 04/0000Z 13.9N 64.9W 45 KT 50 MPH 24H 04/1200Z 14.4N 68.1W 50 KT 60 MPH 36H 05/0000Z 15.0N 71.2W 55 KT 65 MPH 48H 05/1200Z 15.5N 74.5W 60 KT 70 MPH 72H 06/1200Z 17.0N 80.0W 65 KT 75 MPH 96H 07/1200Z 18.5N 83.5W 75 KT 85 MPH 120H 08/1200Z 20.5N 87.0W 80 KT 90 MPH $$ FORECASTER AVILA