WDXS31 PGTW 090900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 11S (FREDDY) WARNING NR 013// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 15.4S 110.3E INITIAL INTENSITY: 60 KTS GEOGRAPHIC REFERENCE: 467 NM NORTH-NORTHWEST OF LEARMONTH, AUSTRALIA MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 07 KTS SIGNIFICANT WAVE HEIGHT: 27 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) INDICATES THAT TC 11S (FREDDY) CONTINUES TO STRUGGLE IN THE FACE OF PERSISTENT, MODERATE EASTERLY SHEAR, PARTICULARLY IN THE MID-LEVELS. 0600Z IMAGERY SHOWED A PARTIALLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC), WITH AN AREA OF FLARING CONVECTION JUST WEST OF THE LLCC. SUBSEQUENT IMAGERY SUGGESTS THIS AREA OF CONVECTION HAS STARTED TO MOVE OVER THE CENTER ONCE MORE, POSSIBLY INDICATING A LESSENING OF THE EASTERLY SHEAR. WATER VAPOR IMAGERY AND JTWC HAND ANALYSIS OF ATMOSPHERIC MOTION VECTOR (AMV) DATA SHOWS THE FIRST HINTS OF AN UPPER-LEVEL POINT SOURCE BEGINNING TO REFORM OVER THE LLCC. A TIMELY 090608Z AMSR2 37GHZ MICROWAVE IMAGE SHOWED A WELL-DEFINED LOW EMISSIVITY REGION AND STRONG SPIRAL BANDING FEATURES FORMING A DEVELOPING EYEWALL, PARTICULARLY ON THE WEST SIDE, WHILE THE EAST SIDE REMAINS DEVOID OF SIGNIFICANT CONVECTION AT THIS TIME. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE AMSR2 IMAGE NOTED ABOVE. PREVIOUS INTENSITY ESTIMATES HAVE BEEN LOWERED BY ABOUT 10 KNOTS AFTER RECEIPT OF A 082212Z RCM-3 SAR PASS WHICH SHOWED A MUCH WEAKER SYSTEM THAN ORIGINALLY THOUGHT. THE INITIAL INTENSITY ON THIS WARNING CONTINUES THE WEAKENING TREND, AND IS LOWERED TO 60 KNOTS. THIS IS BELOW THE BULK OF THE AGENCY CURRENT INTENSITY ESTIMATES, AND MORE IN LINE WITH THE SATCON AND ADT ESTIMATES, SUPPORTED BY A 58 KNOT AMSR2 WINDSPEED MEASUREMENT. DMN AND OPEN-AIIR REMAIN SIGNIFICANTLY LOWER, BETWEEN 45-50 KNOTS. THE OVERALL ENVIRONMENT IS MARGINAL DUE TO THE PERSISTENCE OF THE HIGH EASTERLY SHEAR, CURRENTLY ESTIMATED AT 22 KNOTS. OTHERWISE, ENVIRONMENTAL CONDITIONS ARE FAVORABLE, WITH WARM SSTS AND GOOD EQUATORWARD OUTFLOW. INITIAL WIND RADII BASIS: EARLIER SCATTEROMETER DATA AND AMSR2 WINDSPEED DATA. CURRENT STEERING MECHANISM: NORTHERN PERIPHERY OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) TO THE SOUTH. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T4.5 - 77 KTS KNES: T4.5 - 77 KTS DEMS: T5.0 - 90 KTS APRF: T4.0 - 65 KTS CIMSS SATCON: 62 KTS AT 090612Z CIMSS ADT: 59 KTS AT 090530Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL VWS: 20-25 KTS SST: 29-30 CELSIUS OUTFLOW: MODERATE EQUATORWARD ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: MEDIUM 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: FROM A TRACK PERSPECTIVE, TC 11S CONTINUES TO BE WELL-BEHAVED, WITH NO MAJOR CHANGES FROM THE PREVIOUS TRACK FORECAST EXPECTED. THE SYSTEM WILL CONTINUE TO TRACK ALONG THE NORTHERN SIDE OF A STRONG STR ENTRENCHED TO THE SOUTH FOR THE DURATION OF THE FORECAST, THOUGH A SLIGHT CURVE TO POLEWARD IS EXPECTED AT TAU 120 AS THE RIDGE IS ERODED DUE TO THE APPROACH OF A DEEP, MID-LATITUDE TROUGH. THE SYSTEM CONTINUES TO STRUGGLE AGAINST THE MODERATE TO HIGH EASTERLY SHEAR, BUT THIS IS SOON TO CHANGE AND BASED ON THE LATEST IMAGERY, THE CHANGE MAY HAVE ALREADY BEGUN. HOWEVER, IT WILL TAKE SOME TIME FOR THE SYSTEM TO RESPOND, AND THUS THE FORECAST CALLS FOR SOME FURTHER WEAKENING IN THE NEAR-TERM, BOTTOMING OUT AT TAU 12, OR A BIT SOONER, AT 55 KNOTS. AFTER THIS POINT THE UPPER-LEVEL POINT SOURCE IS FORECAST TO REDEVELOP OVER TOP OF THE SYSTEM, WHICH WILL ALLOW FOR RESUMPTION OF INTENSIFICATION. TC 11S WILL INTENSIFY STEADILY THROUGH TAU 48, REACHING A PEAK OF AT LEAST 80 KNOTS BEFORE THE SYSTEM MOVES OVER MARGINALLY SUPPORTIVE SSTS NEAR 26C AND ANOTHER BURST OF MODERATE SHEAR IMPACTS THE SYSTEM FROM THE NORTHWEST. THESE FACTORS WILL RESULT IN A STEADY WEAKENING TREND WHICH WILL ACCELERATE AFTER TAU 96 DUE TO RAPIDLY INCREASING SHEAR AT THE BASE OF THE APPROACHING MID-LEVEL TROUGH. MODEL DISCUSSION: TRACK GUIDANCE REMAINS IN GOOD AGREEMENT THROUGH TAU 72, WITH THE BULK OF THE CONSENSUS MEMBERS ENCASED WITHIN A 80NM ENVELOPE AT TAU 72. NAVGEM CONTINUES TO BE THE POLEWARD OUTLIER AFTER TAU 72, TURNING THE SYSTEM SHARPLY POLEWARD AS NAVGEM PREDICTS A MUCH SHARPER BREAK IN THE STEERING RIDGE THAN THE OTHER MODELS. THE UKMET MODEL, ALONG WITH THE ENSEMBLE FORECAST A WEAKER TROUGH AND THUS KEEP THE SYSTEM TRACKING DUE WEST THROUGH TAU 120. THE REMAINDER OF THE GUIDANCE PACKAGE ROUGHLY FOLLOWS THE MEDIAN CONSENSUS TRACKER, RIGHT DOWN THE MIDDLE. DISCARDING THE NAVGEM, THE JTWC FORECAST MOST CLOSELY TRACKS THE GFS AND ECMWF SOLUTIONS, THOUGH A BIT SLOWER THAN GFS AND A BIT FASTER THAN ECMWF, ALONG THE SOUTH SIDE OF THE ENVELOPE OF THE BULK OF THE MEMBERS. CONFIDENCE IS HIGH IN THE FIRST 72 HOURS TRENDING TO MEDIUM IN THE LATER TAUS. INTENSITY GUIDANCE SHOWS A LARGE SPREAD IN SOLUTIONS, RANGING FROM 115 KNOTS FROM THE HWRF TO JUST 45 KNOTS FROM THE DECAY SHIPS AND COAMPS-TC (GFS). DUE TO RECENT TRENDS SEEN IN THE SATELLITE IMAGERY AND JTWC ANALYSIS OF THE UPPER-LEVELS CONSISTENT WITH THE GLOBAL MODEL DEPICTIONS, THE FORECAST DISCARDS THE COAMPS-TC AND DECAY SHIPS OUTPUT AND FOLLOWS THE GENERAL TREND LINE OF THE HWRF, THOUGH PEAKS ABOUT 30 KNOTS LOWER. DUE TO THE SMALL NATURE OF THE SYSTEM, RAPID FLUCTUATIONS IN INTENSITY AND HIGHER PEAK INTENSITIES ARE CERTAINLY A POSSIBILITY IF THE UPPER-LEVEL POINT SOURCE CAN EFFECTIVELY BE REESTABLISHED. FORECAST CONFIDENCE: TRACK 0 - 72 HR: HIGH TRACK 72-120 HR: MEDIUM INTENSITY 0 - 72 HR: MEDIUM INTENSITY 72-120 HR: LOW// NNNN