WDXS31 PGTW 141500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 29S (TWENTYNINE) WARNING NR 012// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 14.0S 122.9E INITIAL INTENSITY: 40 KTS GEOGRAPHIC REFERENCE: 237 NM NORTH OF BROOME, AUSTRALIA MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 02 KTS SIGNIFICANT WAVE HEIGHT: 17 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL CYCLONE 29S WITH A COMPACT CORE OF CENTRAL CONVECTION AND A BANDING FEATURE FORMING WITHIN THE NORTHERN PERIPHERY. A 140958Z SSMIS 91 GHZ MICROWAVE IMAGE REVEALED THE DEEP CONVECTION STILL SLIGHTLY DISPLACED TO THE EAST OF THE ASSESSED LOW-LEVEL CIRCULATION CENTER (LLCC). ENVIRONMENTAL ANALYSIS INDICATES THAT 29S IS IN A FAVORABLE ENVIRONMENT CHARACTERIZED BY MODERATE POLEWARD AND EQUATORWARD OUTFLOW, VERY LOW (ABOUT 5 KTS) VERTICAL WIND SHEAR, AND WARM (29-30 C) SEA SURFACE TEMPERATURES. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON THE CLOUD LINE TRACING IN THE ANIMATED EIR IMAGERY. THE INITIAL INTENSITY OF 40 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE AGENCY DVORAK AND OBJECTIVE INTENSITY ESTIMATES LISTED BELOW. INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK CURRENT STEERING MECHANISM: NORTHERN PERIPHERY OF AN EXTENSION OF A SUBTROPICAL RIDGE (STR) POSITIONED TO THE SOUTHWEST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T2.5 - 35 KTS KNES: T2.5 - 35 KTS APRF: T2.0 - 30 KTS CIMSS SATCON: 34 KTS AT 141230Z CIMSS ADT: 45 KTS AT 141200Z CIMSS AIDT: 35 KTS AT 141200Z CIMSS PRINT: 31 KTS AT 141200Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 0-5 KTS SST: 29-30 CELSIUS OUTFLOW: MODERATE POLEWARD AND EQUATORWARD ANALYSIS CONFIDENCE: INITIAL POSITION: MEDIUM INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: LOW 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TC 29S IS FORECAST TO TRACK GENERALLY WESTWARD ALONG THE NORTHERN PERIPHERY OF THE EXTENSION OF THE STR THROUGH TAU 48. NEAR TAU 48, A LONGWAVE TROUGH WILL BREAK DOWN THE RIDGE AND CAUSE 29S TO COME TO A HALT AND BEGIN A SHARP EAST-SOUTHEASTWARD TURN. 29S WILL CONTINUE TO TRACK IN THE EAST-SOUTHEASTWARD DIRECTION THROUGH THE REMAINDER OF THE FORECAST PERIOD TOWARD THE COAST OF NORTHWESTERN AUSTRALIA. REGARDING INTENSITY, TC 29S IS FORECAST TO RAPIDLY INTENSIFY OVER THE NEXT 48 HOURS TO A PEAK OF 110 KTS, DUE TO THE EXPECTED HIGHLY FAVORABLE ENVIRONMENT. SHEAR IS FORECAST TO REMAIN BELOW 10 KTS AND OUTFLOW WILL BECOME STRONG. NEAR TAU 48, WESTERLY SHEAR IS EXPECTED TO BEGIN QUICKLY RISING WITH VALUES NEAR 25 KTS AT TAU 72, 40 KTS AT TAU 96, AND 45 KTS AT TAU 120. THESE HIGH SHEAR VALUES, ALONG WITH INCREASING DRY AIR ENTRAINMENT FROM THE WEST, WILL CAUSE 29S TO RAPIDLY WEAKEN. A DROP TO BELOW 35 KTS IS FORECAST TO OCCUR NEAR THE END OF THE FORECAST PERIOD (TAU 120). MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN GOOD AGREEMENT THROUGH TAU 72 WITH A 120 NM CROSS-TRACK SPREAD AT TAU 72. AFTER TAU 72, MODELS BEGIN TO DIVERGE DUE TO VARYING RESPONSES TO THE INTERACTION WITH THE LONGWAVE TROUGH. MODELS ARE BEGINNING TO COME MORE IN LINE WITH EACH OTHER THOUGH AND NOW HAVE A CLOSER GROUPING AFTER THE EAST-SOUTHEASTWARD TURN. AS A RESULT, THE JTWC TRACK FORECAST IS PLACED WITH HIGH CONFIDENCE THROUGH TAU 72 AND MEDIUM CONFIDENCE THEREAFTER. INTENSITY GUIDANCE CONTINUES TO HAVE MULTIPLE RAPID INTENSIFICATION (RI) AIDS TRIGGERING. PEAK INTENSITIES NOW RANGE FROM 85 KTS (GFS) TO 145 KTS (HAFS-A) AT TAU 48. ALL MODELS CONTINUE TO AGREE ON RAPID WEAKENING AFTER TAU 48. THE JTWC INTENSITY FORECAST IS PLACED WITH OVERALL MEDIUM CONFIDENCE DUE TO SOME INHERENT UNCERTAINTIES REGARDING RI AND THE PEAK INTENSITY OF THE SYSTEM. FORECAST CONFIDENCE: TRACK 0 - 72 HR: HIGH TRACK 72-120 HR: MEDIUM INTENSITY 0 - 72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN