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SUBTROPICAL STORM ONE DISCUSSION NUMBER   1
NATIONAL WEATHER SERVICE MIAMI FL
5 PM EDT FRI OCT 12 2001
 
THE NON-TROPICAL LOW TO THE NORTHWEST OF BERMUDA HAS BEEN LOOKING 
MORE TROPICAL TODAY...WITH THE DEVELOPMENT OF A CONVECTIVE BAND 
NEARLY ENCIRCLING THE CENTER.  RECONNAISSANCE REPORTS INDICATE THAT 
THE SYSTEM HAS A WARM CORE AT THE 850 MB LEVEL...AND THE TEMPERATURE 
PROFILE IS FAIRLY SYMMETRIC.  HOWEVER...THE SYSTEM STILL HAS SOME 
NON-TROPICAL CHARACTERISTICS...INCLUDING ITS LOCATION WITHIN AN 
UPPER LOW...AND AN ELEVATED LEVEL OF MAXIMUM WIND AS EVIDENCED BY 
THE 0000Z BERMUDA SOUNDING.  TWO OTHER FACTORS ARGUE FOR A 
SUBTROPICAL CLASSIFICATION AT THIS TIME.  FIRST...THE MAXIMUM WINDS 
REPORTED BY THE AIRCRAFT WERE NOT ASSOCIATED WITH THE CONVECTIVE 
BAND NOW WRAPPING AROUND THE CENTER...BUT WERE WELL OUTSIDE OF THIS 
BAND ABOUT 80 NM FROM THE CENTER.  SECOND...THE SYSTEM HAS 
APPARENTLY NOT STRENGTHENED APPRECIABLY SINCE BERMUDA OBSERVED A 
SUSTAINED WIND OF 51 KT AT 0200Z...WELL BEFORE THE DEVELOPMENT OF 
THE CONVECTIVE BAND. THIS SUGGESTS THAT THE CYCLONE HAS NOT YET 
TRANSITIONED FROM BAROCLINIC TO CONVECTIVE ENERGETICS.  IT IS 
IMPORTANT TO REMEMBER THAT THERE ARE NO WELL-DEFINED BOUNDARIES 
SEPARATING EXTRATROPICAL...SUBTROPICAL...AND TROPICAL CYCLONES.

THERE ARE INDICATIONS THAT ANTICYCLONIC OUTFLOW IS BEGINNING TO 
DEVELOP AND THIS SYSTEM COULD BECOME A TROPICAL CYCLONE...KAREN... 
AT ANY TIME. BOTH THE GFDL AND SHIPS MODELS FORECAST MODEST 
STRENGTHENING BUT NEITHER MODEL IS DESIGNED FOR THIS KIND OF SYSTEM. 
NONE OF THE GLOBAL MODELS STRENGTHEN THE STORM AND NEITHER DOES THE 
OFFICIAL FORECAST.  NEAR THE END OF THE FORECAST PERIOD COLDER WATER 
SHOULD KILL IT OFF.

THE INITIAL MOTION IS 350/8.  ONLY A SLOW NORTHEASTWARD MOTION IS 
EXPECTED AS STRONG DOWNSTREAM RIDGING IN ADVANCE OF THE DEEP TROUGH 
OVER THE CENTRAL U.S. WILL PARTIALLY BLOCK THE SYSTEMS PROGRESS.  
THE OFFICIAL FORECAST IS NEAR THE AVN/GFDL/UKMET CONSENSUS.

FORECASTER FRANKLIN
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     12/2100Z 33.9N  66.5W    55 KTS
12HR VT     13/0600Z 34.9N  66.6W    55 KTS
24HR VT     13/1800Z 36.0N  66.2W    50 KTS
36HR VT     14/0600Z 37.4N  65.7W    45 KTS
48HR VT     14/1800Z 39.0N  65.0W    45 KTS
72HR VT     15/1800Z 43.0N  62.0W    30 KTS
 
 
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