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Post-Tropical Cyclone NADINE (Text)

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POST-TROPICAL CYCLONE NADINE DISCUSSION NUMBER  43
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL142012
1100 PM AST FRI SEP 21 2012

WHILE NADINE CONTINUES TO MAINTAIN A WARM CORE AND A VIGOROUS
LOW-LEVEL CIRCULATION...THERE HAS BEEN NO SIGNIFICANT CONVECTION
ASSOCIATED WITH THE SYSTEM FOR THE PAST 15 HOURS OR SO.  WHAT
CONVECTION THAT CURRENTLY REMAINS IS IN POORLY-DEFINED BANDS TO THE
SOUTHWEST OF THE CENTER.  BASED ON THIS...THE SYSTEM DOES NOT
REALLY FIT THE DEFINITION OF A SUBTROPICAL CYCLONE AND SO IT IS
DECLARED TO BE POST-TROPICAL.  THE INITIAL INTENSITY IS HELD AT 50
KT DUE TO A LACK OF DATA NEAR THE CENTER...BUT THIS COULD BE A
LITTLE GENEROUS.

THE INITIAL MOTION IS 165/11.  NADINE IS CURRENTLY BEING STEERED BY
A DEEP-LAYER TROUGH TO ITS NORTHEAST.  A GENERALLY SOUTHEASTWARD
MOTION WITH A DECREASE IN FORWARD SPEED IS EXPECTED DURING THE NEXT
24 HOURS.  AFTER THAT...THERE ARE TWO FUTURE TRACK SCENARIOS FOR
NADINE OR ITS REMNANTS.  THE FIRST IS THAT ENOUGH TROUGHING REMAINS
NORTHEAST OF THE CYCLONE TO STEER IT GENERALLY EASTWARD.  THIS
SCENARIO IS SUPPORTED BY THE ECMWF...UKMET...GFDL...AND FLORIDA
STATE SUPERENSEMBLE.  THE SECOND IS THAT DEEP-LAYER RIDGING
DEVELOPS NORTH OF THE CYCLONE AND STEERS IT IN A GENERALLY WEST-
NORTHWESTWARD DIRECTION.  THIS SCENARIO IS SUPPORTED BY THE GFS...
GFS ENSEMBLE MEAN...NOGAPS...AND CANADIAN MODELS.  IT SHOULD BE
NOTED THAT THE VARIOUS ENSEMBLE MEMBERS OF THE ECMWF...GFS...
UKMET...AND CANADIAN MODELS ARE SPLIT BETWEEN THESE TWO
SCENARIOS... MAKING IT DIFFICULT TO TELL WHICH WILL COME TO PASS. 
THE NEW TRACK FORECAST WILL FOLLOW THE EASTWARD SCENARIO FROM THE
PREVIOUS FORECAST...WITH A SLOW FORWARD MOTION DUE TO THE VERY
LARGE SPREAD IN THE GUIDANCE AFTER 24 HOURS.
 
THIS MAY NOT BE THE LAST HURRAH FOR NADINE.  THE CYCLONE IS MOVING
TOWARD WARMER SEA SURFACE TEMPERATURES...AND SEVERAL OF THE GLOBAL
MODELS SHOW A FAVORABLE UPPER-LEVEL WIND PATTERN DEVELOPING OVER
THE SYSTEM IN 48-72 HOURS.  THE SHIPS AND LGEM MODELS FORECAST THE
SYSTEM TO STRENGTHEN AND RE-ACQUIRE TROPICAL CYCLONE
CHARACTERISTICS BY THAT TIME.  THE INTENSITY FORECAST WILL NOT SHOW
A TRANSITION BACK TO A TROPICAL CYCLONE...BUT IT IS A DISTINCT
POSSIBILITY...ESPECIALLY IF THE SYSTEM TURNS WESTWARD UNDER THE
RIDGE.  EVEN IF THIS TRANSITION DOES NOT OCCUR...THE MAJORITY OF
THE DYNAMICAL MODELS MAINTAIN NADINE AS A VIGOROUS CYCLONE THROUGH
THE FORECAST PERIOD...AND THE INTENSITY FORECAST IS THUS CHANGED
LITTLE FROM THE PREVIOUS FORECAST.

THIS WILL BY THE LAST ADVISORY ON NADINE BY THE NATIONAL HURRICANE
CENTER UNLESS REGENERATION OCCURS.

FORECAST POSITIONS AND MAX WINDS
 
INIT  22/0300Z 31.9N  26.6W   50 KT  60 MPH...POST-TROPICAL
 12H  22/1200Z 31.0N  26.1W   45 KT  50 MPH...POST-TROPICAL
 24H  23/0000Z 30.5N  25.2W   45 KT  50 MPH...POST-TROPICAL
 36H  23/1200Z 30.7N  24.5W   45 KT  50 MPH...POST-TROPICAL
 48H  24/0000Z 31.4N  24.5W   45 KT  50 MPH...POST-TROPICAL
 72H  25/0000Z 32.5N  24.5W   50 KT  60 MPH...POST-TROPICAL
 96H  26/0000Z 32.5N  23.0W   55 KT  65 MPH...POST-TROPICAL
120H  27/0000Z 33.0N  20.0W   50 KT  60 MPH...POST-TROPICAL
 
$$
FORECASTER BEVEN
 
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