000
WTNT44 KNHC 140844
TCDAT4
 
TROPICAL STORM NADINE DISCUSSION NUMBER  12
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL142012
500 AM AST FRI SEP 14 2012

THE SATELLITE APPEARANCE OF NADINE HAS BECOME MORE RAGGED DURING THE
PAST FEW HOURS.  THE CENTRAL CONVECTION HAS DECREASED IN BOTH
COVERAGE AND INTENSITY...AND THE CONVECTIVE BANDING IN THE EASTERN
SEMICIRCLE HAS ALSO DIMINISHED.  THIS CHANGE MAY BE DUE TO 20 KT OF
SOUTHWESTERLY VERTICAL WIND SHEAR ANALYZED BY THE SHIPS MODEL AND
BY CIMSS.  SATELLITE INTENSITY ESTIMATES ARE 65 KT FROM TAFB AND 55
KT FROM SAB...SO THE INITIAL INTENSITY REMAINS 60 KT.

NADINE CONTINUES ITS TURN TOWARD THE NORTH WITH AN INITIAL MOTION OF
340/13.  THE OVERALL TRACK FORECAST REASONING IS UNCHANGED...AS
NADINE WILL MOVE AROUND THE RIDGE IN THE NEXT 24 TO 36 HOURS AND
THEN TURN EAST-NORTHEASTWARD OR EASTWARD IN THE MID-LATITUDE
WESTERLIES. THE GUIDANCE IS TIGHTLY CLUSTERED THROUGH ABOUT 36
HOURS...AND THE NHC FORECAST IS LARGELY AN UPDATE OF THE PREVIOUS
ONE THROUGH THAT TIME.  A SIGNIFICANT SPREAD PERSISTS IN THE TRACK
MODELS AFTER THAT TIME.  THE NOGAPS IS A FAR LEFT OUTLIER...SHOWING
A NORTHWARD MOTION BY 120 HR.  THE UKMET AND GFDL ARE ON THE
NORTHERN OR LEFT EDGE OF THE MAIN TRACK GUIDANCE CLUSTER...WHILE
THE THE ECMWF AND FSU SUPERENSEMBLE REMAIN NEAR THE SOUTHERN OR
RIGHT EDGE OF THE MAIN CLUSTER.  THE GFS AND GFS ENSEMBLE MEAN LIE
NEAR THE CENTER OF THE ENVELOPE.  THERE HAS BEEN A SLIGHT SOUTHWARD
SHIFTED OF THE GUIDANCE ENVELOPE SINCE THE LAST ADVISORY...SO THE
FORECAST TRACK AFTER 36 HR IS SHIFTED A LITTLE SOUTHWARD...WHERE IT
LIES NEAR THE GFS AND GFS ENSEMBLE MEAN.

THE GLOBAL MODELS ARE IN GOOD AGREEMENT THAT THE WESTERLY SHEAR
SHOULD INCREASE TO 30-40 KT DURING THE NEXT 24-48 HR.  WHILE MUCH
OF THE INTENSITY GUIDANCE STILL FORECASTS STRENGTHENING...THIS
LOOKS OPTIMISTIC GIVEN THE FORECAST SHEAR VALUES.  THE INTENSITY
FORECAST KEEPS THE WINDS AT 60 KT FOR THE NEXT 48 HR...AND IT WOULD
BE NO SURPRISE IF NADINE WEAKENED INSTEAD.  THE SHEAR IS LIKELY TO
SLOWLY DECREASE AFTER 48 HR...AND THE FORECAST SHOWS A LITTLE
STRENGTHENING DURING THIS TIME WHILE THE CENTER REMAINS OVER WARM
WATER.  THE NEW INTENSITY FORECAST IS IN BEST AGREEMENT WITH THE
LGEM MODEL AND IS WEAKER THAN THE INTENSITY CONSENSUS.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  14/0900Z 26.3N  54.1W   60 KT  70 MPH
 12H  14/1800Z 28.1N  54.2W   60 KT  70 MPH
 24H  15/0600Z 30.1N  53.2W   60 KT  70 MPH
 36H  15/1800Z 31.1N  51.2W   60 KT  70 MPH
 48H  16/0600Z 31.4N  48.9W   60 KT  70 MPH
 72H  17/0600Z 32.0N  43.0W   65 KT  75 MPH
 96H  18/0600Z 33.5N  37.5W   65 KT  75 MPH
120H  19/0600Z 35.5N  32.5W   65 KT  75 MPH
 
$$
FORECASTER BEVEN