000
WTNT44 KNHC 282035
TCDAT4
 
HURRICANE NADINE DISCUSSION NUMBER  65
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL142012
500 PM AST FRI SEP 28 2012

NADINE HAS CHANGED LITTLE IN STRUCTURE DURING THE PAST FEW HOURS. 
AN EYE HAS MADE OCCASIONAL APPEARANCES IN VISIBLE IMAGERY...AND
MICROWAVE IMAGERY SHOWS AN EYE UNDER THE CENTRAL DENSE OVERCAST. 
HOWEVER...THE EYE AT THE MID-LEVEL SEEMS TO BE ABOUT 25 N MI NNE OF
THE SURFACE CENTER...LIKELY DUE TO 20 KT OF SOUTHWESTERLY VERTICAL
WIND SHEAR ANALYZED BY CIMSS AND THE SHIPS MODEL.  REGARDLESS OF
THE TILT AND THE SHEAR...THE CURRENT DVORAK-BASED AND MICROWAVE-
BASED INTENSITY ESTIMATES ALL SUPPORT AN INITIAL INTENSITY OF 65
KT...AS DOES THE CIMSS SATELLITE CONSENSUS METHOD.  THE CIRRUS
OUTFLOW IS CURRENTLY GOOD IN THE NORTHEASTERN SEMICIRCLE AND
RESTRICTED IN THE SOUTHWEST SEMICIRCLE.
 
THE INITIAL MOTION IS NOW 325/7.  FOR THE NEXT 48 HR OR SO NADINE
SHOULD MOVE GENERALLY NORTH-NORTHWESTWARD BETWEEN A DEEP-LAYER
RIDGE OVER THE EASTERN ATLANTIC AND A MID/UPPER-LEVEL LOW CURRENTLY
LOCATED NEAR 32N47W.  THE GLOBAL MODELS FORECAST NADINE TO MERGE OR
MOVE UNDER THIS LOW IN 48-72 HR...WITH THE SYSTEM MOVING SLOWLY
IN AN AREA OF LIGHT STEERING CURRENTS JUST SOUTH OF THE MAIN BRANCH
OF THE WESTERLIES.  THE TRACK FORECAST SHOWS A SLOW MOTION FROM
48-96 HR IN CONTINUITY WITH THE PREVIOUS FORECAST...AND NADINE
COULD PERFORM AN CYCLONIC LOOP DURING THIS TIME AS SHOWN BY THE
ECMWF...UKMET...AND GFDL MODELS.  AFTER 96 HR...THE GLOBAL MODELS
FORECAST THE WESTERLIES TO SINK SOUTHWARD TOWARD NADINE...WHICH
SHOULD STEER THE CYCLONE EASTWARD TO EAST-NORTHEASTWARD.  THE NEW
FORECAST TRACK REMAINS SIMILAR TO THE OLD THROUGH 96 HR...AND IS A
LITTLE FASTER AT 120 HR.  HOWEVER...THE 120-HR POINT IS NOT AS FAR
EAST AS MUCH OF THE GUIDANCE...AND SOME ADJUSTMENT MAY BE NECESSARY
IF THE MODEL TRENDS CONTINUE.

IT NOW APPEARS THAT NADINE WILL ENCOUNTER 15-25 KT OF SOUTHWESTERLY
SHEAR DURING THE NEXT 12-36 HR...AND THE NEW INTENSITY FORECAST NO
LONGER SHOWS ANY STRENGTHENING DURING THIS TIME.  A SHORTWAVE
TROUGH ROTATING AROUND THE MID/UPPER-LEVEL LOW MAY INTERACT WITH
NADINE AROUND 48-72 HR...WHICH COULD PROVIDE AN ENVIRONMENT MORE
FAVORABLE FOR STRENGTHENING.  HOWEVER...THE INTENSITY GUIDANCE IS
CURRENTLY IN TOO POOR OF AGREEMENT ON THIS TO CHANGE THE PREVIOUS
FORECAST.  AFTER 72 HR...INCREASING NORTH TO NORTHWESTERLY SHEAR
AND DECREASING SEA SURFACE TEMPERATURES ALONG THE FORECAST TRACK
SHOULD CAUSE A STEADY WEAKENING.  THE NEW INTENSITY FORECAST IS A
BLEND OF THE INTENSITY CONSENSUS AND THE FLORIDA STATE
SUPERENSEMBLE MODELS.

FORECAST POSITIONS AND MAX WINDS
 
INIT  28/2100Z 30.1N  35.0W   65 KT  75 MPH
 12H  29/0600Z 31.3N  35.7W   65 KT  75 MPH
 24H  29/1800Z 33.2N  36.4W   65 KT  75 MPH
 36H  30/0600Z 35.1N  37.0W   65 KT  75 MPH
 48H  30/1800Z 36.1N  37.3W   65 KT  75 MPH
 72H  01/1800Z 36.5N  37.5W   60 KT  70 MPH
 96H  02/1800Z 36.5N  37.0W   55 KT  65 MPH
120H  03/1800Z 36.5N  35.5W   45 KT  50 MPH
 
$$
FORECASTER BEVEN