000
WTNT41 KNHC 240853
TCDAT1
 
TROPICAL STORM OPHELIA DISCUSSION NUMBER  14
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL162011
500 AM AST SAT SEP 24 2011
 
OPHELIA HAS NOT CHANGED A LOT DURING THE PAST SEVERAL HOURS...WITH
THE CENTER STAYING MOSTLY EXPOSED TO THE SOUTHWEST OF A LARGE AREA
OF CONVECTION. THE INITIAL INTENSITY WILL REMAIN 45 KT FOR THIS
ADVISORY...ALTHOUGH THE CYCLONE MIGHT BE A LITTLE WEAKER THAN THAT.
MODERATE TO STRONG SOUTHWESTERLY SHEAR SHOULD REMAIN IN PLACE FOR
THE NEXT SEVERAL DAYS DUE TO A PERSISTENT UPPER-LEVEL TROUGH TO THE
WEST OF OPHELIA. GIVEN THE HOSTILE CONDITIONS...IT SEEMS LIKELY
THAT THE CYCLONE WILL GRADUALLY WEAKEN DURING THE NEXT 2 OR 3
DAYS...AND THE NHC INTENSITY FORECAST HAS BEEN ADJUSTED DOWNWARD
THROUGH THAT TIME. AFTER 72 HOURS...THE GLOBAL MODELS ARE STILL
HINTING THAT THE UPPER-LEVEL TROUGH COULD FRACTURE AND ALLOW
RESTRENGTHENING OF THE TROPICAL CYCLONE. THIS IDEA IS REFLECTED IN
THE OFFICIAL FORECAST...WHICH SHOWS A MODEST INCREASE IN STRENGTH
AT DAYS 4 AND 5. THE NHC FORECAST IS SHADED TOWARD THE STATISTICAL
LGEM/SHIPS GUIDANCE...AND IS BELOW THE INTENSITY CONSENSUS. 

NIGHT-VISIBLE IMAGERY SUGGESTS THAT OPHELIA HAS TURNED TOWARD THE
NORTHWEST WITH A FORWARD SPEED OF ABOUT 12 KT. WHILE THE MODEL
GUIDANCE IS IN FAIR AGREEMENT ON THIS TRACK CONTINUING FOR A DAY OR
SO...THE DIFFERENCES BECOME QUITE LARGE AFTER THAT TIME. THESE
DIFFERENCES APPEAR TO BE RELATED TO THE STRENGTH OF THE TROPICAL
CYCLONE. IF SYSTEM IS WEAK...OPHELIA IS MORE LIKELY TO CONTINUE
MOVING TOWARD THE WEST-NORTHWEST OR NORTHWEST UNDER THE LOW-LEVEL
RIDGE. HOWEVER...IF OPHELIA IS DEEP ENOUGH TO FEEL A BREAK IN THE
MID-LEVEL RIDGE AROUND 65W...A TURN TOWARD THE NORTH IS MORE LIKELY
WITH A LARGE DECREASE IN FORWARD SPEED. SINCE THE OFFICIAL FORECAST
SHOWS SOME INCREASE IN STRENGTH AT THE END OF THE PERIOD...IT WILL
LEAN TOWARD THE LATTER SCENARIO...AND RESULTS IN AN EASTWARD SHIFT
OF THE NHC TRACK FROM THE PREVIOUS PACKAGE. 
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  24/0900Z 16.9N  55.2W   45 KT  50 MPH
 12H  24/1800Z 18.0N  56.6W   45 KT  50 MPH
 24H  25/0600Z 19.2N  58.4W   40 KT  45 MPH
 36H  25/1800Z 20.2N  60.0W   40 KT  45 MPH
 48H  26/0600Z 21.0N  61.5W   35 KT  40 MPH
 72H  27/0600Z 22.5N  63.0W   35 KT  40 MPH
 96H  28/0600Z 24.5N  63.5W   40 KT  45 MPH
120H  29/0600Z 26.5N  63.5W   50 KT  60 MPH
 
$$
FORECASTER BLAKE