000 WTNT43 KNHC 090837 TCDAT3 TROPICAL STORM CHANTAL DISCUSSION NUMBER 6 NWS NATIONAL HURRICANE CENTER MIAMI FL AL032013 500 AM AST TUE JUL 09 2013 CHANTAL HAS CHANGED LITTLE IN STRUCTURE OVER THE LAST SEVERAL HOURS. RADAR DATA FROM BARBADOS AND SATELLITE IMAGES INDICATE THAT THE CENTER IS LOCATED ON THE NORTH-NORTHWEST SIDE OF THE COLDEST CLOUD TOPS AND SHOWER ACTIVITY. OVERALL THE CLOUD PATTERN IS NOT VERY WELL ORGANIZED AND LACKS WELL-DEFINED BANDING FEATURES. THE INITIAL WIND SPEED IS HELD AT 45 KT...IN AGREEMENT WITH THE DVORAK CLASSIFICATIONS AND ASCAT DATA. AN AIR FORCE RECONNAISSANCE AIRCRAFT IS SCHEDULED TO INVESTIGATE CHANTAL LATER THIS MORNING AND WILL PROVIDE A BETTER ASSESSMENT OF ITS INTENSITY. THE TROPICAL STORM CONTINUES TO RACE WEST-NORTHWESTWARD...WITH THE LATEST INITIAL MOTION ESTIMATE BEING 290/23. A CONTINUED FAST WEST-NORTHWESTWARD MOTION IS EXPECTED FOR THE NEXT DAY OR SO AS THE STORM REMAINS TO THE SOUTH OF A SUBTROPICAL RIDGE OVER THE CENTRAL ATLANTIC. THIS MOTION SHOULD TAKE CHANTAL ACROSS THE LESSER ANTILLES LATER THIS MORNING...AND NEAR HISPANIOLA ON WEDNESDAY. BEYOND THAT TIME...THE GLOBAL MODELS SHOW A TROUGH MOVING ACROSS THE EASTERN UNITED STATES. THIS TROUGH SHOULD WEAKEN THE RIDGE AND CAUSE CHANTAL TO SLOW DOWN AND TURN TOWARD THE NORTH-NORTHWEST. A SLIGHT LEFT TURN IS PREDICTED BY THE END OF THE FORECAST PERIOD AS THE MODELS SHOW A RIDGE REBUILDING TO THE NORTHEAST OF CHANTAL BY THAT TIME. THE NHC TRACK FORECAST IS AN UPDATE OF THE PREVIOUS ONE FOR THE FIRST COUPLE OF DAYS AND IS SHIFTED A LITTLE TO THE EAST THEREAFTER...TO COME INTO BETTER AGREEMENT WITH THE LATEST GUIDANCE. SLOW STRENGTHENING IS FORECAST FOR THE NEXT 36 HOURS AS CHANTAL REMAINS OVER WARM WATER AND IN AN ENVIRONMENT OF MODERATE WIND SHEAR. PRONOUNCED WEAKENING IS THEN EXPECTED WHEN CHANTAL MOVES OVER OR INTERACTS WITH THE RUGGED TERRAIN OF HISPANIOLA. IF THE CYCLONE SURVIVES ITS TREK ACROSS HISPANIOLA...IT COULD RE-INTENSIFY AS THE ENVIRONMENTAL WIND PATTERN IS ANTICIPATED TO BECOME MORE FAVORABLE BY THE TIME THE SYSTEM REACHES THE BAHAMAS. ONLY SLIGHT MODIFICATIONS WERE MADE TO THE WIND SPEED FORECAST OF THE PREVIOUS ADVISORY...AND THE LATEST NHC INTENSITY FORECAST IS MORE OR LESS IN LINE WITH THE FLORIDA STATE SUPERENSEMBLE AND THE INTENSITY MODEL CONSENSUS. FORECAST POSITIONS AND MAX WINDS INIT 09/0900Z 13.3N 58.4W 45 KT 50 MPH 12H 09/1800Z 14.6N 61.7W 50 KT 60 MPH 24H 10/0600Z 16.3N 65.9W 55 KT 65 MPH 36H 10/1800Z 18.2N 69.4W 60 KT 70 MPH 48H 11/0600Z 20.1N 72.0W 40 KT 45 MPH 72H 12/0600Z 23.5N 74.8W 40 KT 45 MPH 96H 13/0600Z 26.5N 76.0W 45 KT 50 MPH 120H 14/0600Z 28.5N 77.5W 50 KT 60 MPH $$ FORECASTER CANGIALOSI/PASCH