Tropical Storm ILEANA

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TROPICAL STORM ILEANA DISCUSSION NUMBER   2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP102006
200 PM PDT MON AUG 21 2006
 
VISIBLE SATELLITE PICTURES SHOW AN IMPRESSIVE CURVED BAND FORMING IN
THE SOUTHERN SEMICIRCLE OF THE LARGE SYSTEM ALONG WITH PLENTY OF
BANDING TO THE NORTH OF THE CENTER.  A 29 KT WIND REPORT WAS
ALSO RECEIVED FROM SHIP ELTZ7 A FEW HUNDRED MILES NORTHEAST OF THE
CENTER OUTSIDE OF THE STRONGEST CONVECTION. WITH THE IMPROVING
SATELLITE PRESENTATION AND DT NUMBERS AT 2.5 OR ABOVE... AT LEAST
35 KT... THE NINTH TROPICAL STORM OF THE SEASON IS BORN.
 
CIRRUS OUTFLOW FROM ILEANA IS EXPANDING IN ALL DIRECTIONS...
ESPECIALLY TO THE SOUTH. WATER VAPOR IMAGES INDICATE AN UPPER-LEVEL
RIDGE AXIS LIES JUST TO THE NORTH OF THE STORM PROVIDING EASTERLY
UPPER-LEVEL FLOW... AND CONSEQUENTLY LIGHT SHEAR. GLOBAL MODELS
SUGGEST ILEANA WILL REMAIN ON THE SOUTHERN SIDE OF THIS RIDGE... A
FAVORABLE SPOT FOR FUTURE INTENSIFICATION... FOR AT LEAST THE NEXT
COUPLE OF DAYS. IN ADDITION... RATHER WARM WATERS GREATER THAN 29C
ALSO LIE ALONG THAT TRACK.  THE SHIPS MODEL RESPONDS TO THESE
CONDUCIVE PARAMETERS BY INTENSIFYING ILEANA TO HURRICANE-STRENGTH
IN A LITTLE OVER 24 HOURS AND 88 KT IN 60 HOURS... JUST ABOUT AS
FAST AN INTENSIFICATION AS THE STATISTICAL MODEL CAN PRODUCE. THIS
PROJECTION MAY NOT BE UNREALISTIC GIVEN THE EASTERN PACIFIC RAPID
INTENSIFICATION INDEX WHICH SHOWS A 73% CHANCE OF A 25 KT OR MORE
INCREASE IN THE NEXT 24 HOURS. THE INTENSITY FORECAST IS CLOSE TO
SHIPS AND SHOWS RAPID INTENSIFICATION FOR THE FIRST 24 HOURS
FOLLOWED BY A MORE MODEST STRENGTHENING THEREAFTER. WEAKENING IS
SHOWN AFTER 72 HOURS BECAUSE OF THE SYSTEM PASSING THE 26C
ISOTHERM. 
 
THE INITIAL HEADING IS ABOUT 300 AT 10 KT.  GLOBAL MODELS SUGGEST
THAT MIDDLE-LEVEL RIDGING OVER THE SOUTH-CENTRAL UNITED STATES AND
NORTHERN MEXICO WILL BUILD WESTWARD WITH TIME.  THIS SHOULD KEEP
THE STORM ON A WEST-NORTHWEST TO NORTHWESTWARD TRACK. MODEL GUIDANCE
SHOWS THIS SCENARIO WITH SOME SMALL DISAGREEMENTS.  THE GFDL...
WHICH HAD BEEN ON THE RIGHT SIDE OF THE GUIDANCE... HAS SHIFTED
LEFTWARD... LIKE THE GFS.  THE UKMET AND ECMWF ARE TO THE RIGHT OF
THE MODEL CONSENSUS THOUGH ALL MODELS STAY OFFSHORE OF MEXICO. 
SINCE THE GFS/GFS ENSEMBLE HAVE SHOWN GOOD CONSISTENCY AND
REPRESENTATIONS OF THE CYCLONE... THE OFFICIAL FORECAST IS SHIFTED
A LITTLE LEFT OF THE PREVIOUS ONE... A TOUCH SOUTH OF THE MODEL
CONSENSUS.  WIND RADII HAVE BEEN ENLARGED TO ACCOUNT FOR THE LARGE
SIZE OF THE SYSTEM DOCUMENTED FROM SATELLITE AND SHIP REPORTS.  
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      21/2100Z 12.8N 103.2W    35 KT
 12HR VT     22/0600Z 13.6N 104.6W    45 KT
 24HR VT     22/1800Z 14.7N 106.6W    60 KT
 36HR VT     23/0600Z 15.9N 108.7W    70 KT
 48HR VT     23/1800Z 17.3N 110.9W    80 KT
 72HR VT     24/1800Z 20.0N 115.0W    85 KT
 96HR VT     25/1800Z 22.0N 118.5W    75 KT
120HR VT     26/1800Z 24.0N 122.0W    50 KT
 
$$
FORECASTER BLAKE/FRANKLIN
 
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