000 WTNT44 KNHC 030236 TCDAT4 TROPICAL STORM NADINE DISCUSSION NUMBER 82 NWS NATIONAL HURRICANE CENTER MIAMI FL AL142012 1100 PM AST TUE OCT 02 2012 NADINE IS BEGINNING TO SHOW SIGNS OF BECOMING SHEARED APART AS THE UPPER-LEVEL TROUGH THAT HAS BEEN PROTECTING IT MOVES OFF TO THE EAST...EXPOSING THE CYCLONE TO INCREASING NORTHWESTERLY WINDS. THE INITIAL INTENSITY OF 45 KT IS BASED ON A BLEND OF SATELLITE T-NUMBERS AND CI-NUMBERS FROM TAFB AND SAB. WIND RADII WERE ADJUSTED INWARD SLIGHTLY BASED ON A PARTIAL ASCAT PASS AT 02/2317 UTC...WHICH CAUGHT THE WESTERN SEMICIRCLE OF NADINE. THE INITIAL MOTION ESTIMATE IS 090/08 KT. THERE IS NO SIGNIFICANT CHANGE TO PREVIOUS FORECAST TRACK OR REASONING. THE NHC MODEL GUIDANCE REMAINS IN GOOD AGREEMENT ON NADINE GRADUALLY TURNING NORTHEASTWARD OVER THE NEXT 24 HOURS AND MOVING THROUGH THE CENTRAL OR WESTERN AZORES IN ABOUT 30 HOURS. IN THE 36- TO 72-HOUR TIME FRAME...THE CYCLONE IS EXPECTED TO TURN NORTHWARD AS IT IS STEERED AROUND A MUCH LARGER DEEP-LAYER TROUGH/LOW CURRENTLY EAST OF NEWFOUNDLAND THAT IS FORECAST TO DIG SOUTHEASTWARD INTO THE CENTRAL ATLANTIC AND AMPLIFY OVER THE NEXT 3 DAYS. THE OFFICIAL FORECAST TRACK IS SIMILAR TO THE PREVIOUS ADVISORY...AND LIES CLOSE TO THE MIDDLE OF THE TIGHTLY PACKED NHC GUIDANCE ENVELOPE. THE AFOREMENTIONED SHEAR PATTERN COULD BECOME MORE PRONOUNCED OVER THE NEXT 24 HOURS...WHICH SHOULD RESULT IN AT LEAST SOME GRADUAL WEAKENING. AS NADINE APPROACHES AND EVENTUALLY MOVES NORTH OF THE AZORES ISLANDS...SEA SURFACE TEMPERATURES WILL SHARPLY DECREASE TO LESS THAN 20C. THE COMBINATION OF SHEAR AND COOLER WATERS WOULD NORMALLY PRODUCE RAPID WEAKENING AND/OR DISSIPATION OF THE TROPICAL CYCLONE. IN THIS CASE...HOWEVER...THE MIDDLE AND UPPER TROPOSPHERE IS ALSO FORECAST TO COOL...WHICH COULD RESULT IN JUST ENOUGH INSTABILITY TO PRODUCE SOME MODERATE CONVECTION AND ALLOW NADINE TO HANG ON TO TROPICAL CYCLONE STATUS AS IT PASSES THROUGH THE AZORES. BY 48 HOURS...HOSTILE VERTICAL SHEAR CONDITIONS ASSOCIATED WITH THE AMPLIFYING DEEP-LAYER TROUGH/LOW SHOULD BRING ABOUT A RAPID DEMISE OF NADINE BY DAY 3...WITH ITS REMNANTS BEING ABSORBED INTO A VERY LARGE EXTRATROPICAL LOW BY DAY 4. FORECAST POSITIONS AND MAX WINDS INIT 03/0300Z 34.4N 35.7W 45 KT 50 MPH 12H 03/1200Z 35.2N 33.8W 45 KT 50 MPH 24H 04/0000Z 37.2N 30.9W 45 KT 50 MPH...SOUTHWEST OF AZORES 36H 04/1200Z 40.8N 28.2W 45 KT 50 MPH...NORTH OF AZORES 48H 05/0000Z 44.6N 26.4W 40 KT 45 MPH...POST-TROPICAL 72H 06/0000Z 48.0N 28.0W 40 KT 45 MPH...POST-TROP/EXTRATROP 96H 07/0000Z...DISSIPATED $$ FORECASTER STEWART