Tropical Storm HELENE

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TROPICAL STORM HELENE DISCUSSION NUMBER  14
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082006
500 PM EDT FRI SEP 15 2006
 
HELENE IS DEFINITELY STRENGTHENING AT THIS TIME AND IS VERY NEAR
HURRICANE STATUS. SATELLITE IMAGES SHOW AN IMPRESSIVE
CYCLONICALLY-CURVED CONVECTIVE BAND WRAPPING AROUND THE CENTER. THE
OUTFLOW IS WELL-ESTABLISHED AND IS MOST IMPRESSIVE TO THE WEST AND
SOUTH OF THE CYCLONE.  ALL INDICATIONS ARE THAT HELENE WILL
CONTINUE IN A LOW-SHEAR ENVIRONMENT AND WILL BE MOVING OVER WARMER
WATERS...ACCORDING TO BUOY DATA NEARBY. THERE ARE NO OTHER APPARENT
CONDITIONS THAT COULD HALT ADDITIONAL STRENGTHENING OVER THE NEXT 2
TO 3 DAYS.

HELENE IS MOVING TOWARD THE WEST-NORTHWEST OR 300 DEGREES...BACK AT
THE EARLIER SPEED OF 13 KNOTS...AROUND THE PERIPHERY OF THE
SUBTROPICAL RIDGE. A STRONG MID-LATITUDE TROUGH...WHICH IS FORECAST
TO BE OVER THE WESTERN ATLANTIC...WILL LIKELY ERODE THE RIDGE.
THE EXPECTED STEERING PATTERN WILL FORCE HELENE TO GRADUALLY TURN TO
THE NORTHWEST AS INDICATED IN THE OFFICIAL FORECAST. THIS IS THE
GENERAL SOLUTION PROVIDED BY MOST OF THE GUIDANCE BUT MODELS VARY
IN HOW FAR WEST THEY BRING HELENE DEPENDING ON EACH MODEL'S
FORECAST REPRESENTATION OF THE RIDGE. NEVERTHELESS...NO MODEL
BRINGS HELENE PAST 60W LONGITUDE IN FIVE DAYS IN THE LATEST MORNING
RUN...AND IN FACT...MOST OF THEM TURN THE CYCLONE NORTHWARD.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      15/2100Z 16.7N  42.8W    60 KT
 12HR VT     16/0600Z 17.7N  44.5W    70 KT
 24HR VT     16/1800Z 18.6N  46.0W    75 KT
 36HR VT     17/0600Z 19.5N  47.5W    85 KT
 48HR VT     17/1800Z 20.5N  49.0W    95 KT
 72HR VT     18/1800Z 22.0N  51.0W   100 KT
 96HR VT     19/1800Z 24.0N  54.0W    95 KT
120HR VT     20/1800Z 26.0N  56.5W    90 KT
 
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FORECASTER AVILA
 
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