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Tropical Storm ILEANA (Text)

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TROPICAL STORM ILEANA DISCUSSION NUMBER   2
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP092012
800 PM PDT MON AUG 27 2012
 
THE CLOUD PATTERN OF THE SYSTEM HAS BECOME BETTER ORGANIZED WITH A
CENTRAL DENSE OVERCAST AND DISTINCT BANDING FEATURES.  SATELLITE
INTENSITY ESTIMATES WERE 35 KT AND 45 KT FROM SAB/TAFB RESPECTIVELY
AT 0000 UTC...AND 40 KT IS CHOSEN AS THE INITIAL WIND SPEED.  THE
UPPER-LEVEL OUTFLOW PATTERN OF THE TROPICAL STORM IS RATHER
IMPRESSIVE WITH LIGHT SHEAR FORECAST FOR THE NEXT FEW DAYS...AND
ILEANA SHOULD BE MOVING OVER WATERS THAT HAVE BEEN UNTOUCHED BY ANY
RECENT CYCLONE ACTIVITY.  THUS STEADY INTENSIFICATION IS FORECAST...
AND THE NHC OFFICIAL FORECAST IS RAISED FROM THE PREVIOUS ONE...
CLOSEST TO A BLEND OF THE LGEM MODEL AND THE INTENSITY CONSENSUS.
IT SHOULD BE NOTED THAT THIS FORECAST COULD BE CONSERVATIVE GIVEN
THE FORECAST UPPER-LEVEL PATTERN...BUT I WANTED TO KEEP SOME
CONTINUITY FROM THE PREVIOUS PREDICTION.  WEAKENING SHOULD BEGIN IN
ABOUT 4 DAYS AS ILEANA MOVES OVER COLDER WATERS.
 
THE LATEST MOTION ESTIMATE IS ABOUT 290/10 KT.  A MID-LEVEL RIDGE
OVER THE SOUTHWESTERN UNITED STATES SHOULD PROVIDE THE PRIMARY
STEERING CURRENT FOR THE NEXT SEVERAL DAYS...CAUSING ILEANA TO MOVE
WEST-NORTHWEST OR NORTHWEST.  HOWEVER...THERE ARE SOME DIFFERENCES
INITIALLY ON HOW ILEANA INTERACTS WITH THE ITCZ TO THE SOUTHWEST.
THE GFS KEEPS THE SYSTEM MORE EMBEDDED WITHIN THE ITCZ AND SHOWS A
MORE WESTWARD TRACK...WHILE THE ECMWF HAS THE CYCLONE BREAKING FREE
FROM THE ITCZ AND HEADING NORTHWESTWARD.  THE GFS SOLUTION SEEMS
LESS REALISTIC...AND THE OFFICIAL FORECAST HAS BEEN SHIFTED TO THE
RIGHT IN THE FIRST COUPLE OF DAYS.  A LEFTWARD BEND SHOULD OCCUR IN
A FEW DAYS TIME AS ILEANA WEAKENS AND BECOMES MORE STEERED BY THE
LOW-LEVEL FLOW.  THE NHC TRACK PREDICTION IS BASICALLY AN UPDATE OF
THE PREVIOUS ONE AT THE LONGER RANGE...AND IS NOT TOO FAR FROM
TVCN.
 
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  28/0300Z 15.5N 107.7W   40 KT  45 MPH
 12H  28/1200Z 16.0N 109.1W   50 KT  60 MPH
 24H  29/0000Z 16.6N 110.6W   60 KT  70 MPH
 36H  29/1200Z 17.3N 111.9W   65 KT  75 MPH
 48H  30/0000Z 18.1N 112.8W   70 KT  80 MPH
 72H  31/0000Z 19.5N 114.0W   75 KT  85 MPH
 96H  01/0000Z 21.0N 115.5W   65 KT  75 MPH
120H  02/0000Z 22.5N 119.0W   50 KT  60 MPH
 
$$
FORECASTER BLAKE
 
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