ZCZC MIATCDEP5 ALL TTAA00 KNHC DDHHMM 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 NNNN
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Page last modified: Monday, 11-Sep-2006 11:28:43 UTC