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Subtropical Storm MELISSA (Text)

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SUBTROPICAL STORM MELISSA DISCUSSION NUMBER   1
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL142013
1100 AM EDT MON NOV 18 2013
 
DEEP CONVECTION HAS DEVELOPED DURING THE PAST SEVERAL HOURS NEAR THE
WELL-DEFINED CENTER OF A LARGE GALE-AREA LOCATED OVER THE CENTRAL
ATLANTIC WELL TO THE EAST-SOUTHEAST OF BERMUDA.  FRONTAL BOUNDARIES
NEAR THE CENTER APPEAR TO HAVE DISSIPATED AND SO ADVISORIES ARE
BEING INITIATED AT THIS TIME.  ALTHOUGH THERE ARE HINTS OF
ANTICYCLONIC OUTFLOW HAVING RECENTLY DEVELOPED OVER THE INNER CORE
CONVECTION...THE SYSTEM IS STILL WELL-EMBEDDED WITHIN AN
UPPER-LEVEL LOW AND THE MOST RECENT SCATTEROMETER WIND DATA SUGGEST
THAT THE CYCLONE MAY STILL HAVE A LARGE RADIUS OF MAXIMUM WINDS. 
AS A RESULT...THE SYSTEM IS BEING DESIGNATED AS A SUBTROPICAL STORM
RATHER THAN A TROPICAL STORM...AT LEAST FOR NOW.  

THE INITIAL MOTION ESTIMATE IS NORTHWESTWARD...OR 320/08 KT. NHC
MODEL GUIDANCE IS IN EXCELLENT AGREEMENT ON MELISSA MOVING
NORTHWESTWARD AND GRADUALLY SLOWING DOWN OVER THE NEXT 24 HOURS OR
SO AS IT MOVES AROUND THE WESTERN PERIPHERY OF A HIGH-AMPLITUDE
RIDGE LOCATED BETWEEN THE CYCLONE AND THE AZORES. THE CYCLONE COULD
POSSIBLY BECOME STATIONARY FOR A BRIEF PERIOD ON TUESDAY WHEN THE
SYSTEM MOVES UNDERNEATH A 200 MB LOW/TROUGH. HOWEVER...BY 48 HORUS
AND BEYOND...A DEEP-LAYER TROUGH LOCATED OVER THE EASTERN PORTIONS
OF CANADA AND THE UNITED SATES IS EXPECTED TO ACCELERATE MELISSA TO
THE NORTHEAST. BY DAYS 4 AND 5...MELISSA IS FORECAST OT INTERACT
WITH THE AFOREMENTIONED DEEPENING TROUGH AND TURN BACK TOWARD THE
NORTH AND NORTHWEST OVER THE FAR NORTH ATLANTIC. THE OFFICIAL
FORECAST TRACK IS CLOSE TO THE MULTI-MODEL CONSENSUS TVCA.

MELISSA HAS ABOUT 48 HOURS OR SO TO STRENGTHEN...AND THE SHIPS
INTENSITY MODEL INDICATES THAT THE VERTICAL SHEAR IS EXPECTED TO
DECREASE TO LESS THAN 10 KT BY 36 HOURS. THE WEAKENING SHEAR SHOULD
ALLOW FOR AT LEAST SOME MODEST STRENGTHENING TO OCCUR WHILE THE
CYCLONE REMAINS OVER RELATIVELY WARM WATER...BUT ALSO ALLOW FOR THE
TRANSITION TO A TROPICAL CYCLONE. THE NHC INTENSITY FORECAST IS
SIMILAR TO THE ICON INTENSITY FORECAST MODEL. HOWEVER...IT IS NOT
OUT OF THE QUESTION THAT MELISSA COULD ATTAIN HURRICANE STATUS IN
36-48 HOURS WHEN THE VERTICAL SHEAR IS AT A MINIMUM.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  18/1500Z 29.3N  53.6W   45 KT  50 MPH
 12H  19/0000Z 30.2N  54.4W   50 KT  60 MPH
 24H  19/1200Z 31.3N  54.3W   55 KT  65 MPH
 36H  20/0000Z 33.6N  52.3W   60 KT  70 MPH
 48H  20/1200Z 36.6N  48.9W   60 KT  70 MPH
 72H  21/1200Z 42.8N  39.4W   55 KT  65 MPH...POST-TROP/EXTRATROP
 96H  22/1200Z 50.0N  35.0W   45 KT  50 MPH...POST-TROP/EXTRATROP
120H  23/1200Z 55.0N  39.0W   45 KT  50 MPH...POST-TROP/EXTRATROP
 
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FORECASTER STEWART
 
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