000 WTNT44 KNHC 131449 TCDAT4 TROPICAL STORM NADINE DISCUSSION NUMBER 9 NWS NATIONAL HURRICANE CENTER MIAMI FL AL142012 ISSUED BY THE HYDROMETEOROLOGICAL PREDICTION CENTER COLLEGE PARK MD 1100 AM AST THU SEP 13 2012 BASED ON VISIBLE AND INFRARED SATELLITE IMAGERY...NADINE HAS NOT BECOME SIGNIFICANTLY BETTER ORGANIZED THIS MORNING. THERE IS A GOOD CONCENTRATION OF DEEP CONVECTION IN A SMALL AREA NEAR THE CENTER...BUT NADINE HAS YET TO DISPLAY ANY SIGN OF EYE FORMATION ON GEOSTATIONARY IMAGES. THE OVERALL CLOUD PATTERN REMAINS SOMEWHAT ASYMMETRIC...WITH MORE DEEP CONVECTION OVER THE EASTERN SEMICIRCLE. ARC CLOUDS HAVE BEEN NOTED EMANATING NORTHWARD FROM THE STORM... SUGGESTING SOME INTRUSION OF MID-LEVEL DRY AIR. DVORAK CURRENT INTENSITY ESTIMATES FROM TAFB AND SAB REMAIN UNCHANGED FROM THE PREVIOUS CYCLE...SO THE ADVISORY WIND SPEED IS HELD AT 60 KT. ALTHOUGH THE CENTER IS NOT THAT EASY TO LOCATE...MOST RECENT SATELLITE FIXES GIVE A MOTION ESTIMATE OF 315/14. THE STEERING SCENARIO AND TRACK FORECAST FOR THE NEXT TWO DAYS APPEAR TO BE RELATIVELY STRAIGHTFORWARD. NADINE SHOULD CONTINUE TO MOVE AROUND THE WESTERN PERIPHERY OF A SUBTROPICAL ANTICYCLONE...AND THE TRACK MODELS ARE IN REASONABLY GOOD AGREEMENT THROUGH 48 HOURS. LATER ON...THE TRACK MODELS BECOME MORE DIVERGENT...WITH A SPREAD OF OVER 600 N MI BY DAY 5. THE GFDL IS THE LEFT-MOST OF THE MODEL SUITE...AND IS CONSIDERED AN OUTLIER AT THIS TIME. THE MOST LIKELY OUTCOME DURING DAYS 3-5 SEEMS TO BE AN EAST-NORTHEASTWARD TO EASTWARD MOTION WITHIN THE MID-LEVEL WESTERLIES TO THE NORTH OF THE SUBTROPICAL RIDGE. THEREFORE...THE OFFICIAL FORECAST TRACK IS CLOSE TO A SELECTIVE CONSENSUS THAT EXCLUDES THE GFDL. THIS IS ALSO ROUGHLY IN AGREEMENT WITH THE PREVIOUS NHC FORECAST THROUGH 72 HOURS...AND A LITTLE TO THE RIGHT AT THE LONGER TIME RANGES. NADINE IS CURRENTLY EXPERIENCING MODERATE SOUTHWESTERLY SHEAR ASSOCIATED WITH A MID- TO UPPER-LEVEL TROUGH AND SHEAR AXIS LOCATED A FEW HUNDRED MILES TO ITS WEST. ANALYSIS OF THE GFS MODEL FIELDS REVEALS THE SHEAR IS MOST PROMINENT IN THE MID LEVELS AT THIS TIME. DYNAMICAL GUIDANCE INDICATES SHEAR WILL BECOME RATHER STRONG BY 36 HOURS AND BEYOND. ALTHOUGH THE STORM IS RUNNING OUT OF TIME TO BECOME A HURRICANE...SOME OF THE BETTER-PERFORMING GUIDANCE SUCH AS SHIPS SHOW SOME STRENGTHENING WITHIN THE NEXT 24-36 HOURS. THE OFFICIAL INTENSITY FORECAST CONTINUES TO CALL FOR NADINE TO STRENGTHEN INTO A HURRICANE IN THE SHORT TERM...WITH GRADUAL WEAKENING PREDICTED AS SHEAR INCREASES BEYOND 36 HOURS. FORECAST POSITIONS AND MAX WINDS INIT 13/1500Z 22.6N 52.2W 60 KT 70 MPH 12H 14/0000Z 24.2N 53.3W 65 KT 75 MPH 24H 14/1200Z 26.4N 54.2W 70 KT 80 MPH 36H 15/0000Z 28.6N 53.8W 70 KT 80 MPH 48H 15/1200Z 30.1N 52.6W 65 KT 75 MPH 72H 16/1200Z 31.8N 48.2W 60 KT 70 MPH 96H 17/1200Z 32.5N 42.5W 60 KT 70 MPH 120H 18/1200Z 34.0N 37.0W 60 KT 70 MPH $$ FORECASTER BURKE/PASCH