000 WTNT44 KNHC 171442 TCDAT4 TROPICAL STORM NADINE DISCUSSION NUMBER 25 NWS NATIONAL HURRICANE CENTER MIAMI FL AL142012 1100 AM AST MON SEP 17 2012 THE INNER-CORE CONVECTION HAS CONTINUED TO WEAKEN SINCE THE PREVIOUS ADVISORY AS DRIER AND MORE STABLE AIR HAS WRAPPED INTO THE SYSTEM FROM THE WEST AND SOUTH. RECENT AMSU SATELLITE INTENSITY ESTIMATES RANGE FROM 63 KT TO 77 KT...AND THE 12Z TAFB CURRENT INTENSITY ESTIMATE WAS T3.5/55 KT. AN AVERAGE OF THESE ESTIMATES SUPPORTS MAINTAINING AN INITIAL INTENSITY OF 60 KT. THE INITIAL MOTION ESTIMATE IS NOW 050/13 KT. A GRADUAL TURN TOWARD THE NORTH-NORTHEAST AND NORTH WITH A FURTHER REDUCTION IN FORWARD SPEED IS EXPECTED OVER THE NEXT 72 HOURS AS NADINE IS INFLUENCED BY SOUTHERLY FLOW ON THE EAST SIDE OF A DEEP-LAYER TROUGH LOCATED TO ITS WEST. AFTER DAY 3...NADINE WILL INTERACT WITH A DEEP MID- TO UPPER-LEVEL LOW FORECAST TO DEVELOP TO THE NORTH OF THE CYCLONE AND DROP SOUTHWARD TO NEAR THE AZORES ON DAY 5. THE EXPECTED BINARY INTERACTION BETWEEN THESE TWO SYSTEMS COULD RESULT IN SOME ERRATIC MOTION...WITH NADINE POSSIBLY EVEN BECOMING STATIONARY AT TIMES IN THE VICINITY OF THE AZORES. THE LATEST NHC MODEL GUIDANCE IS IN MUCH BETTER AGREEMENT ON THIS DEVELOPING SCENARIO AS COMPARED TO PREVIOUS ADVISORIES. THE OFFICIAL FORECAST TRACK IS SIMILAR TO THE PREVIOUS ADVISORY TRACK AND LIES CLOSE TO A BLEND OF THE CONSENSUS MODELS TVCA AND THE HFIP MODEL TV15...AND THE FLORIDA STATE SUPERENSEMBLE MODEL. THE INTRUSIONS OF DRIER...STABLE AIR IS BEING OFFSET SOMEWHAT BY THE IMPRESSIVE OUTFLOW REGIME THAT HAS FORMED OVER THE PAST 12 HOURS... AS SUGGESTED BY A RECENT BURST OF DEEP CONVECTION THAT HAS DEVELOPED JUST NORTHEAST OF THE LOW-LEVEL CENTER. HOWEVER...COOLER SSTS AND INCREASING VERTICAL WIND SHEAR BY 24 HOURS AND BEYOND SHOULD STEADILY TAKE THEIR TOLL...CAUSING NADINE TO GRADUALLY WEAKEN. BY 96 HOURS...INTERACTION WITH THE DEVELOPING LOW TO THE NORTH OF NADINE...COUPLED WITH SSTS COOLER THAN 22C...IS EXPECTED TO RESULT IN THE CYCLONE TRANSITIONING INTO A SIGNIFICANT EXTRATROPICAL LOW...OR POSSIBLY EVEN A SUBTROPICAL LOW PRESSURE SYSTEM. THE OFFICIAL INTENSITY FORECAST IS NEARLY IDENTICAL TO THE PREVIOUS ADVISORY...AND IS SIMILAR TO THE CONSENSUS MODELS IV15 AND ICON... WHICH ARE ON THE LOWER END OF THE GUIDANCE SUITE. FORECAST POSITIONS AND MAX WINDS INIT 17/1500Z 32.9N 35.3W 60 KT 70 MPH 12H 18/0000Z 33.7N 34.1W 55 KT 65 MPH 24H 18/1200Z 34.7N 33.0W 55 KT 65 MPH 36H 19/0000Z 35.9N 32.6W 55 KT 65 MPH 48H 19/1200Z 36.9N 32.4W 50 KT 60 MPH 72H 20/1200Z 37.3N 30.5W 50 KT 60 MPH 96H 21/1200Z 36.8N 29.0W 50 KT 60 MPH...POST-TROP/EXTRATROP 120H 22/1200Z 36.5N 28.0W 50 KT 60 MPH...POST-TROP/EXTRATROP $$ FORECASTER STEWART