| Track: http://www.nhc.noaa.gov/refresh/graphics_at1+shtml/024430.shtml?5day?large#contents TROPICAL STORM OPHELIA DISCUSSION NUMBER 1 NWS NATIONAL HURRICANE CENTER MIAMI FL AL162011 1100 PM EDT TUE SEP 20 2011 THE LOW OVER THE TROPICAL ATLANTIC HAS FINALLY COALESCED ABOUT A SINGLE CIRCULATION CENTER AND HAS ENOUGH ORGANIZED DEEP CONVECTION TO BE CONSIDERED A TROPICAL CYCLONE. AN ASCAT PASS JUST BEFORE 00Z SHOWED AN AREA OF 35 KT WINDS NORTH OF THE CENTER...AND THAT IS THE INITIAL INTENSITY FOR THIS ADVISORY. THE SATELLITE PRESENTATION OF OPHELIA IS STILL A LITTLE RAGGED...WITH CONVECTIVE BANDS LOCATED WELL NORTHEAST AND SOUTH OF THE STILL CONSOLIDATING CENTER. WHILE OPHELIA WILL BE MOVING OVER WARM WATERS THROUGH THE PERIOD...THE SHEAR IS EXPECTED TO REMAIN AROUND 15 KT OR SO OVER THE NEXT COUPLE OF DAYS. AFTER THAT TIME...THE SHEAR SHOULD INCREASE AND BECOME MORE WESTERLY AS THE GLOBAL MODELS SHOW AN UPPER-LEVEL LOW FORMING NORTH OF PUERTO RICO. GIVEN THE MARGINAL ENVIRONMENT AND THE SOMEWHAT SPRAWLING NATURE OF THE CYCLONE AT THIS TIME...ONLY MODEST STRENGTHENING IS SHOWN IN THE SHORT TERM. BEYOND 36 HOURS...LITTLE CHANGE IN STRENGTH IS FORECAST...FOLLOWED BY WEAKENING LATE IN THE PERIOD. THE NHC FORECAST IS NEAR OR A LITTLE ABOVE THE IVCN INTENSITY CONSENSUS THROUGH THE PERIOD. THE INITIAL MOTION ESTIMATE IS A RATHER UNCERTAIN 270/8...DUE TO THE RECENT REFORMATION OF THE CENTER. OPHELIA IS CURRENTLY BEING STEERED BY THE SUBTROPICAL RIDGE TO ITS NORTH...AND A WESTWARD MOTION IS EXPECTED OVER THE NEXT COUPLE OF DAYS AS THE RIDGE BUILDS WESTWARD. AFTER THAT TIME...THE RIDGE BEGINS TO WEAKEN AS A LARGE MID/UPPER-LEVEL CLOSED LOW DEVELOPS OVER THE SOUTHEASTERN UNITED STATES...WHICH SHOULD RESULT IN A TURN TOWARD THE WEST-NORTHWEST AND A DECREASE IN FORWARD SPEED LATE IN THE PERIOD. THE NHC TRACK FORECAST LIES TO THE RIGHT OF THE MULTI-MODEL CONSENSUS THROUGH THE PERIOD...BUT IS A LITTLE TO THE LEFT OF THE GFS AND ECMWF MODELS. FORECAST POSITIONS AND MAX WINDS INIT 21/0300Z 12.2N 40.1W 35 KT 40 MPH 12H 21/1200Z 12.4N 42.2W 40 KT 45 MPH 24H 22/0000Z 12.7N 44.9W 45 KT 50 MPH 36H 22/1200Z 12.9N 47.7W 45 KT 50 MPH 48H 23/0000Z 13.2N 50.5W 45 KT 50 MPH 72H 24/0000Z 15.0N 55.5W 45 KT 50 MPH 96H 25/0000Z 17.0N 60.0W 40 KT 45 MPH 120H 26/0000Z 19.0N 64.0W 40 KT 45 MPH $$ FORECASTER BRENNAN TROPICAL STORM OPHELIA ADVISORY NUMBER 1 NWS NATIONAL HURRICANE CENTER MIAMI FL AL162011 1100 PM EDT TUE SEP 20 2011 ...NEW TROPICAL STORM FORMS OVER THE CENTRAL TROPICAL ATLANTIC... SUMMARY OF 1100 PM EDT...0300 UTC...INFORMATION ----------------------------------------------- LOCATION...12.2N 40.1W ABOUT 1585 MI...2555 KM ESE OF THE NORTHERN LEEWARD ISLANDS MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H PRESENT MOVEMENT...W OR 270 DEGREES AT 9 MPH...15 KM/H MINIMUM CENTRAL PRESSURE...1006 MB...29.71 INCHES WATCHES AND WARNINGS -------------------- THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT. DISCUSSION AND 48-HOUR OUTLOOK ------------------------------ AT 1100 PM EDT...0300 UTC...THE CENTER OF TROPICAL STORM OPHELIA WAS LOCATED NEAR LATITUDE 12.2 NORTH...LONGITUDE 40.1 WEST. OPHELIA IS MOVING TOWARD THE WEST NEAR 9 MPH...15 KM/H...AND THIS GENERAL MOTION IS EXPECTED TO CONTINUE FOR THE NEXT 48 HOURS WITH AN INCREASE IN FORWARD SPEED. MAXIMUM SUSTAINED WINDS ARE NEAR 40 MPH...65 KM/H...WITH HIGHER GUSTS. SOME GRADUAL STRENGTHENING IS FORECAST DURING THE NEXT DAY OR SO. TROPICAL-STORM-FORCE WINDS EXTEND OUTWARD UP TO 175 MILES...280 KM...MAINLY TO THE NORTH OF THE CENTER. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1006 MB...29.71 INCHES. HAZARDS AFFECTING LAND ---------------------- NONE NEXT ADVISORY ------------- NEXT COMPLETE ADVISORY...500 AM EDT. $$ FORECASTER BRENNAN |