Tropical Storm NADINE

ZCZC MIATCDAT4 ALL
TTAA00 KNHC DDHHMM
 
TROPICAL STORM NADINE DISCUSSION NUMBER   6
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL142012
ISSUED BY THE HYDROMETEOROLOGICAL PREDICTION CENTER COLLEGE PARK MD
500 PM AST WED SEP 12 2012
 
THE SYSTEM HAS BECOME A LITTLE MORE ASYMMETRIC...WITH A COMMA-TYPE
CLOUD APPEARANCE ON SATELLITE IMAGERY.  DRY AIR ROTATING AROUND THE
NORTHERN SIDE OF THE CYCLONE COULD BE ERODING CONVECTION OVER THE
WESTERN SEMICIRCLE.  HOWEVER...THE CENTRAL DENSE OVERCAST HAS
INCREASED SOMEWHAT IN SIZE AND DVORAK INTENSITY ESTIMATES ARE 55 KT
FROM BOTH AGENCIES.  ON THIS BASIS...THE ADVISORY INTENSITY HAS
BEEN INCREASED TO 55 KT.  CIRRUS CLOUD MOTIONS CONTINUE TO INDICATE
A WELL-DEFINED UPPER-TROPOSPHERIC OUTFLOW PATTERN...AND DYNAMICAL
GUIDANCE INDICATES THE VERTICAL WIND SHEAR SHOULD REMAIN MODERATE
FOR THE NEXT 36-48 HOURS.  LATER IN THE FORECAST PERIOD AS NADINE
MOVES NORTH OF 30N LATITUDE...THE GLOBAL MODELS SHOW A SIGNIFICANT
INCREASE IN THE UPPER-LEVEL WESTERLY FLOW NEAR AND OVER NADINE. 
THEREFORE...STRENGTHENING SHOULD BE LIMITED TO THE EARLY PART OF
THE FORECAST PERIOD AND A WEAKENING TREND SHOULD COMMENCE WITHIN A
COUPLE OF DAYS.  IT SHOULD BE NOTED THAT THE LGEM GUIDANCE SHOWS
MORE WEAKENING THAN THE OFFICIAL FORECAST DURING THE LATTER HALF OF
THE PERIOD.  WHILE THE 1200 UTC ECMWF SOLUTION SHOWS THE
POSSIBILITY OF EXTRATROPICAL TRANSITION AT THE END OF THE
PERIOD...THE MAJORITY OF THE 1200 UTC GLOBAL GUIDANCE DOES NOT. 
UNTIL THERE IS GREATER AGREEMENT AMONGST THE GLOBAL GUIDANCE...THIS
TRANSITION WILL NOT BE INDICATED IN THE OFFICIAL FORECAST.
 
THE HEADING OF THE STORM HAS SHIFTED SLIGHTLY TO THE RIGHT AND THE
MOTION IS NOW ABOUT 310/14.  THERE HAS BEEN LITTLE CHANGE TO THE
TRACK FORECAST PHILOSOPHY.  NADINE IS EXPECTED TO ROUND THE WESTERN
PERIPHERY OF A SUBTROPICAL RIDGE OVER THE EAST-CENTRAL ATLANTIC
WITHIN THE NEXT COUPLE DAYS.  THE CYCLONE SHOULD THEN TURN
EAST-NORTHEASTWARD TO EASTWARD AFTER MOVING NORTH OF THE RIDGE
AXIS.  THE GLOBAL MODEL TRACK GUIDANCE...IN PARTICULAR THE ECMWF..
HAS SHIFTED SOUTHWARD IN THE LATTER PART OF THE FORECAST PERIOD. 
THE 4- AND 5-DAY NHC TRACK HAS BEEN ADJUSTED SOUTH OF THE PREVIOUS
ONE...AND IS CLOSEST TO THE FLORIDA STATE UNIVERSITY SUPERENSEMBLE. 
THIS GUIDANCE HAS BEEN A STRONG PERFORMER FOR TRACK PREDICTION THIS
YEAR.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  12/2100Z 20.0N  48.9W   55 KT  65 MPH
 12H  13/0600Z 21.3N  50.4W   65 KT  75 MPH
 24H  13/1800Z 23.3N  52.3W   70 KT  80 MPH
 36H  14/0600Z 25.5N  53.8W   75 KT  85 MPH
 48H  14/1800Z 28.0N  54.0W   75 KT  85 MPH
 72H  15/1800Z 31.0N  51.0W   70 KT  80 MPH
 96H  16/1800Z 32.5N  46.0W   70 KT  80 MPH
120H  17/1800Z 33.0N  40.0W   65 KT  75 MPH
 
$$
FORECASTER ROTH/PASCH
 
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