ZCZC MIATCDAT3 ALL TTAA00 KNHC DDHHMM TROPICAL STORM CHANTAL DISCUSSION NUMBER 8 NWS NATIONAL HURRICANE CENTER MIAMI FL AL032013 500 PM AST TUE JUL 09 2013 CHANTAL PRODUCED TROPICAL STORM CONDITIONS ALONG ITS PATH THROUGH THE WINDWARD ISLANDS THIS MORNING. THE HIGHEST OBSERVED WIND GUST...68 KT...WAS REPORTED BY METEO-FRANCE AT LAMENTIN AIRPORT IN MARTINIQUE. ALTHOUGH THE SATELLITE PRESENTATION CONTINUES TO BE RAGGED...THE CYCLONE HAS A VERY SMALL CENTER OF CIRCULATION AS INDICATED BY AN AIR FORCE RECONNAISSANCE AIRCRAFT...WITH THE STRONGEST WINDS TO THE NORTH AND EAST OF THE CENTER. THE INITIAL INTENSITY HAS BEEN SET AT 55 KNOTS. ONLY A SLIGHT INCREASE IN THE WINDS IS FORECAST BEFORE CHANTAL CROSSES HISPANIOLA...WHERE WEAKENING IS EXPECTED. AFTER THAT...THE UPPER-LEVEL WINDS ARE NOT PARTICULARLY FAVORABLE...BUT COULD ALLOW MODEST RESTRENGTHENING AS THE CYCLONE MOVES ACROSS THE BAHAMAS. THE INTENSITY FORECAST IS VERY CLOSE TO THE MODEL CONSENSUS. CHANTAL CONTINUES RACING TOWARD THE WEST-NORTHWEST OR 295 DEGREES AT 23 KNOTS...STEERED BY STRONG EASTERLY FLOW SOUTH OF THE SUBTROPICAL RIDGE OVER THE WESTERN ATLANTIC. AS THE STORM MOVES OVER THE EASTERN CARIBBEAN AND HISPANIOLA...THE HIGH TO THE NORTH IS FORECAST TO WEAKEN. THE CYCLONE SHOULD THEN TURN MORE TOWARD THE NORTHWEST WITH A DECREASE IN FORWARD SPEED AS A MID-LEVEL TROUGH DEVELOPS ALONG THE UNITED STATES EAST COAST AND THE STEERING CURRENTS WEAKEN. THE GUIDANCE ENVELOPE SHIFTED WESTWARD IN THE LAST RUN AND CONSEQUENTLY...THE OFFICIAL FORECAST WAS ADJUSTED IN THAT DIRECTION...BUT NOT AS FAR AS THE MODEL CONSENSUS. IF THIS WESTWARD MODEL TREND CONTINUES IN THE NEXT CYCLE...I WILL NOT BE SURPRISED IF ANOTHER WESTWARD SHIFT WILL BE REQUIRED. FORECAST POSITIONS AND MAX WINDS INIT 09/2100Z 15.2N 63.7W 55 KT 65 MPH 12H 10/0600Z 16.5N 66.9W 55 KT 65 MPH 24H 10/1800Z 18.0N 70.4W 60 KT 70 MPH 36H 11/0600Z 20.0N 73.5W 35 KT 40 MPH 48H 11/1800Z 22.0N 75.4W 40 KT 45 MPH 72H 12/1800Z 26.0N 77.5W 45 KT 50 MPH 96H 13/1800Z 28.0N 78.9W 45 KT 50 MPH 120H 14/1800Z 31.1N 80.0W 40 KT 45 MPH $$ FORECASTER AVILA NNNN