WDXS32 PGTW 262100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 22S (GARANCE) WARNING NR 004// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 17.7S 54.5E INITIAL INTENSITY: 85 KTS GEOGRAPHIC REFERENCE: 174 NM NORTH-NORTHWEST OF ST DENIS MOVEMENT PAST 6 HOURS: EAST-SOUTHEASTWARD AT 04 KTS SIGNIFICANT WAVE HEIGHT: 29 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A COMPACT SYSTEM, WITH DEEP CONVECTION IN THE VICINITY OF THE CENTER ATTEMPTING TO FORM AN EYE. SO FAR HOWEVER, THE EYE HAS YET TO BECOME VISIBLE IN THE EIR, YET IT IS VERY CLEAR IN EARLY MICROWAVE IMAGERY AS WELL AS SCATTEROMETER AND SAR DATA. A 261506Z SSMIS 91GHZ MICROWAVE IMAGE REVEALED A WELL-DEFINED MICROWAVE EYE FEATURE, WITH DEEP CONVECTIVE BANDS NEARLY ENCIRCLING THE EYE, THOUGH THE BANDS WERE STILL FRAGMENTED ON THE EASTERN SIDE. AMBIGUITY ANALYSIS OF A 261734Z ASCAT-C PASS PROVIDED HIGH CONFIDENCE TO THE INITIAL POSITION. THE INTENSITY TRENDS GOING BACK TO 1200Z HAVE BEEN UPDATED BASED ON A SERIES OF WINDSPEED MEASUREMENTS INCLUDING COINCIDENT COLLECTIONS AT 261413Z (SMOS), 261446Z (SEN-1A SAR) AND 261456Z (RCM-1 SAR), ALL OF WHICH SHOWED SIMILAR WIND FIELDS, WITH VMAX BETWEEN 75 AND 95 KNOTS. THE INITIAL INTENSITY FOR THIS WARNING IS INCREASED TO 85 KNOTS, BASED ON A BLEND OF THE MEASUREMENTS ABOVE, AND THE OBJECTIVE AND SUBJECTIVE INTENSITY ESTIMATES. THE ENVIRONMENT REMAINS FAVORABLE FOR ADDITIONAL INTENSIFICATION, WITH LOW WIND SHEAR, WARM SSTS AND GOOD POLEWARD AND EQUATORWARD OUTFLOW. INITIAL WIND RADII BASIS: SAR AND SCATTEROMETER DATA. CURRENT STEERING MECHANISM: THE PRIMARY STEERING INFLUENCE IS CURRENTLY SHIFTING FROM THE SOUTHERN PERIPHERY OF A NEAR EQUATORIAL RIDGE (NER) TO THE NORTH, TO THE WESTERN PERIPHERY OF A SUBTROPICAL RIDGE (STR) TO THE EAST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T4.5 - 77 KTS KNES: T4.5 - 77 KTS DEMS: T4.5 - 77 KTS FMEE: T4.5 - 77 KTS CIMSS SATCON: 82 KTS AT 261730Z CIMSS ADT: 74 KTS AT 261800Z CIMSS AIDT: 81 KTS AT 261730Z CIMSS D-MINT: 81 KTS AT 261505Z CIMSS D-PRINT: 71 KTS AT 261830Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 10-15 KTS SST: 28-29 CELSIUS OUTFLOW: STRONG POLEWARD AND EQUATORWARD OTHER FACTORS: COMPACT SIZE OF THE INNER CORE. ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: HIGH INITIAL WIND RADII: HIGH 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TC 22S HAS BEGUN TO TURN TOWARDS THE EAST WHILE SLOWING DOWN AS THE STEERING INFLUENCE BEGINS TO SHIFT FROM THE NER TO THE NORTH-SOUTH ORIENTED STR TO THE EAST. OVER THE NEXT 12 TO 24 HOURS, THE SYSTEM WILL CONTINUE TO TURN POLEWARD, THOUGH FORWARD TRACK SPEEDS ARE EXPECTED TO REMAIN RELATIVELY SLOW. ONCE FIRMLY ON THE POLEWARD TRAJECTORY, BY AROUND TAU 24, THE SYSTEM WILL START TO ACCELERATE SOUTHWARD. LANDFALL ON THE NORTHERN SHORE OF LA REUNION IS EXPECTED AROUND 0000Z ON THE 28TH. THE SYSTEM CONTINUES TO ACCELERATE POLEWARD AFTER CROSSING OVER LA REUNION, WILL ROUND THE RIDGE AXIS BY TAU 48 AND THEN TURN SOUTHEAST THEN EAST BY THE END OF THE FORECAST PERIOD. BASED ON THE LATEST CIMSS AMV ANALYSIS, THE SYSTEM IS SITUATED JUST EAST OF A DEEP, NORTHEAST TO SOUTHEAST ORIENTED TROUGH WHICH EXTENDS FROM AN UPPER-LEVEL LOW POSITIONED NEAR 27S 51E, OVER LA REUNION AND TO THE NORTHEASTERN TIP OF MADAGASCAR. THIS UPPER-LEVEL ORIENTATION IS PROVIDING THE SYSTEM WITH VERY GOOD OUTFLOW CONDITIONS, WITH A STRENGTHENING POLEWARD OUTFLOW CHANNEL ADDING TO THE ALREADY STRONG EQUATORWARD OUTFLOW. THE FAVORABLE CONDITIONS ARE EXPECTED TO LAST FOR ANOTHER 24 HOURS OR SO, ALLOWING THE SYSTEM TO CONTINUE TO INTENSIFY, TO A PEAK OF AT LEAST 105 KNOTS BY TAU 24. THE SYSTEM WILL BEGIN TO FEEL THE EFFECTS OF INCREASING WIND SHEAR AS IT APPROACHES LANDFALL BUT WILL STILL BE A POWERFUL STORM AS IT MAKES LANDFALL AT LA REUNION. SHEAR IS FORECAST TO RAPIDLY INCREASE BY TAU 36, AND THE SYSTEM WILL BE COMPLETELY SHEARED APART BY ABOUT TAU 48 AS IT ROUNDS THE RIDGE AXIS. SLOW BUT STEADY WEAKENING IS FORECAST FROM TAU 48 THROUGH THE END OF THE FORECAST PERIOD. MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE IS IN TIGHT AGREEMENT, PARTICULARLY THROUGH TAU 48, WITH A CROSS-TRACK SPREAD OF JUST 45NM AT TAU 36. THE GUIDANCE PACKAGE DID SHIFT SLIGHTLY WESTWARD AS A WHOLE OVER THE LAST 12 HOURS, WITH THE CONSENSUS MEAN NOW SITUATED ON THE WESTERN PORTION OF LA REUNION VICE DIRECTLY IN THE CENTER, HOWEVER THE OVERALL SCENARIO HAS NOT CHANGED SIGNIFICANTLY. MODEL DISPERSION INCREASES AFTER TAU 48, OPENING UP TO ABOUT 178NM BY TAU 72 AND MAINTAINING THAT ORIENTATION THROUGH THE REMAINDER OF THE FORECAST PERIOD. THE JTWC FORECAST LIES JUST EAST OF THE CONSENSUS MEAN, CLOSE TO THE ECMWF DETERMINISTIC AND EC-AIFS, BOTH OF WHICH ARE ON THE EASTERN SIDE OF THE GUIDANCE PACKAGE. INTENSITY GUIDANCE IS ALSO IN GOOD AGREEMENT THAT THE SYSTEM WILL CONTINUE TO INTENSIFY FOR THE NEXT 24 HOURS. THE HAFS-A, ALONG WITH THE DTOP RAPID INTENSIFICATION (RI) AID CONTINUE TO TRIGGER, PEAKING THE SYSTEM AT 120-125 KNOTS, WHILE THE COAMPS-TC AND THE CONSENSUS MEAN SHOW A PEAK BETWEEN 100-110 KNOTS. THE JTWC FORECAST SPLITS THE DIFFERENCE BETWEEN THE MORE AGGRESSIVE RI AIDS AND THE CONSENSUS MEAN. HOWEVER, THE COMPACT NATURE OF THE SYSTEM MEANS THAT SIGNIFICANT DEVIATIONS FROM THE INTENSITY FORECAST ARE LIKELY. FORECAST CONFIDENCE: TRACK 0 - 72 HR: HIGH TRACK 72-120 HR: MEDIUM INTENSITY 0 - 72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN