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TROPICAL DEPRESSION HELENE DISCUSSION NUMBER  18
NATIONAL WEATHER SERVICE MIAMI FL
5 PM EDT FRI SEP 22 2000
 
HELENE IS NOW A BROAD SWIRL OF LOW CLOUDS WITH A BURST OF CONVECTION
EAST OF THE CENTER.  SURFACE OBSERVATIONS INDICATE THE CENTRAL
PRESSURE HAS RISEN TO NEAR 1010 MB...AND THE HIGHEST SUSTAINED WIND
DURING THE PAST FEW HOURS IS 23 KT AT ALBANY GEORGIA.  THE MAXIMUM
WINDS ARE SET TO 25 KT.

THE INITIAL MOTION IS NOW 045/15.  ALL INDICATIONS ARE THAT HELENE
SHOULD GRADUALLY ACCELERATE IN A NORTHEASTERLY OR EAST-NORTHEASTERLY
DIRECTION THROUGH THE FORECAST PERIOD.  THE TRACK FORECAST IS
BASICALLY AN UPDATE OF THE PREVIOUS PACKAGE.

HELENE SHOULD WEAKEN SLOWLY OR CHANGE LITTLE WHILE OVER LAND.  THE
BIG QUESTION IS WHAT HAPPENS WHEN THE CYCLONE OR ITS REMAINS MOVE
INTO THE ATLANTIC IN 30-36 HR.  THE AVN...GFDL...AND NOGAPS SUGGEST
THE POSSIBILITY OF SOME INTENSIFICATION AT THAT TIME.  HOW THIS
MIGHT HAPPEN IS NOT CLEAR.  THE MODELS DO NOT INDICATE A SHORTWAVE
TROUGH TO TRIGGER A BAROCLINIC DEEPENING...AND THE CYCLONE SHOULD BE
MOSTLY NORTH OF THE GULF STREAM...WHICH WOULD HAMPER RE-DEVELOPMENT
AS A TROPICAL CYCLONE.  THE INTENSITY FORECAST WILL FOLLOW THE
PREVIOUS PACKAGE AND CALL FOR SOME STRENGTHENING...MAINLY DUE TO
INCREASE IN WINDS FROM THE FORWARD SPEED.  WITH THE UNCERTAINTY IN
WHAT THE CYCLONE STRUCTURE WILL BE AS HELENE APPROACHES THE COAST...
AND THE FACT THAT OTHER CYCLONES SUCH AS DANNY HAVE STRENGTHENED
UNEXPECTEDLY BETWEEN THE APPALACHIANS AND THE ATLANTIC...RE-
DEVELOPMENT AS A TROPICAL CYCLONE CANNOT BE RULED OUT.
 
THE COMBINATION OF THE CYCLONE...AN OLD FRONTAL BOUNDARY TO THE
NORTH...AND THE APPALACHIANS SHOULD CONTINUE SPREADING HEAVY RAINS
ACROSS THE SOUTHEASTERN UNITED STATES UNTIL HELENE MOVES INTO THE
ATLANTIC.

THIS WILL BE THE LAST ADVISORY ON HELENE FROM THE NATIONAL HURRICANE
CENTER UNLESS REGENERATION OCCURS.  FUTURE INFORMATION WILL BE
CONTAINED IN STORM SUMMARIES FROM THE HYDROMETEOROLOGICAL PREDICTION
CENTER AND MARINE FORECASTS FROM THE MARINE PREDICTION CENTER.
 
FORECASTER BEVEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     22/2100Z 32.3N  84.6W    25 KTS...INLAND
12HR VT     23/0600Z 33.5N  82.7W    25 KTS...INLAND
24HR VT     23/1800Z 35.4N  79.1W    25 KTS...INLAND
36HR VT     24/0600Z 37.7N  74.2W    35 KTS...EXTRATROPICAL
48HR VT     24/1800Z 40.5N  67.5W    40 KTS...EXTRATROPICAL
72HR VT     25/1800Z 46.5N  52.0W    45 KTS...EXTRATROPICAL
 
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