WDPS31 PGTW 212100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 27P (NARELLE) WARNING NR 016// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 13.6S 135.7E INITIAL INTENSITY: 75 KTS GEOGRAPHIC REFERENCE: 288 NM EAST-SOUTHEAST OF DARWIN, AUSTRALIA MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 12 KTS SIGNIFICANT WAVE HEIGHT: OVER LAND SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) AND SHORTWAVE INFRARED (SWIR) SATELLITE IMAGERY DEPICT A RAPIDLY WEAKENING SYSTEM MOVING INLAND WEST OF GROOTE EYLANDT. TC 27P MADE LANDFALL ALONG THE WEST COAST OF THE GULF OF CARPENTARIA, SOUTH OF GOVE, AUSTRALIA, AT APPROXIMATELY 211400Z BASED ON RADAR ANALYSIS. AT THE TIME OF LANDFALL, THE EIR AND RADAR DATA INDICATED A WELL-DEFINED EYE FEATURE AND AN EARLIER SYNTHETIC APERTURE RADAR (SAR) PASS REVEALED AN AVERAGE VMAX OF 90 KNOTS. LANDFALL INTENSITY WAS THUS SET AT 85 KNOTS. SUBSEQUENT TO LANDFALL, THE SYSTEM MADE A SLIGHT SOUTHWESTWARD JOG BUT HAS SINCE LEVELED OUT ONTO A MORE WESTWARD TRAJECTORY. THE OVERALL DEPICTION IN ANIMATED EIR AND SWIR, AS WELL AS THE RADAR DATA, HAVE RAPIDLY DETERIORATED AS THE SYSTEM PUSHES FURTHER INLAND AND BEGINS TO INTERACT WITH THE TOPOGRAPHY. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE RADAR ANALYSIS. THE INITIAL INTENSITY IS ASSESSED WITH MEDIUM CONFIDENCE, BASED ON AVAILABLE OBJECTIVE INTENSITY ESTIMATES. ENVIRONMENTAL CONDITIONS ARE CONSIDERED AS UNFAVORABLE DUE TO THE SYSTEM BEING OVER LAND. INITIAL WIND RADII BASIS: SAR DATA CURRENT STEERING MECHANISM: NORTHERN PERIPHERY OF A DEEP LAYER SUBTROPICAL RIDGE (STR) ANCHORED OVER CENTRAL AUSTRALIA. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: NO CURRENT ESTIMATE ADRM: T4.0 - 65 KTS CIMSS SATCON: 80 KTS AT 211607Z CIMSS AIDT: 81 KTS AT 211600Z CIMSS D-MINT: 75 KTS AT 211608Z CIMSS D-PRINT: 68 KTS AT 211800Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE VWS: 10-15 KTS SST: 29-30 CELSIUS OUTFLOW: MODERATE EQUATORWARD OTHER FACTORS: DRY AIR ENTRAINMENT; LAND INTERACTION. ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: HIGH 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TROPICAL CYCLONE (TC) 27P IS FORECAST TO CONTINUE TRACKING WEST-SOUTHWESTWARD ALONG THE NORTHERN PERIPHERY OF THE DEEP STR OVER CENTRAL AUSTRALIA FOR THE NEXT 72 HOURS. THE TRACK WILL TAKE THE SYSTEM ACROSS THE TOP END, WELL SOUTH OF DARWIN OVER THE NEXT 24 HOURS, THEN QUICKLY CROSS THE JOSEPH BONAPARTE GULF BY TAU 36. THE SYSTEM IS FORECAST TO MOVE INTO THE INDIAN OCEAN, PASSING NEAR ADELE ISLAND, AROUND TAU 60, THEN PASS NORTH OF BROOME BY TAU 72. AT THIS POINT, THE TRACK FORECAST BECOMES MORE UNCERTAIN AS THE EXACT EVOLUTION OF THE STEERING RIDGE WILL PLAY AN OUTSIZE ROLE IN THE ULTIMATE TRACK. THE GFS SHOWS A FLATTER, MORE EAST-WEST ORIENTED RIDGE ANCHORED FURTHER TO THE SOUTHWEST, WHILE THE ECMWF DEPICTS A MORE SYMMETRICAL RIDGE POSITIONED FURTHER EAST AND A WEAKNESS IN THE RIDGE NEAR LEARMONTH. BOTH MODELS HAVE INITIALIZED VERY SIMILARLY, SO DETERMINING WHICH WILL PROVE MORE ACCURATE AFTER TAU 72 IS CURRENTLY UNRESOLVABLE. THE CURRENT FORECAST IS PLACED CONSISTENT WITH THE PREVIOUS FORECAST, TAKING THE CENTER APPROXIMATELY 100NM WEST-NORTHWEST OF LEARMONTH BY TAU 120. BY THE END OF THE FORECAST, THE SYSTEM WILL REACH THE INFLECTION POINT AT WHICH IT WILL BEGIN TO ROUND THE RIDGE AXIS AND TURN POLEWARD, THE ONLY QUESTION BEING HOW FAR OFFSHORE WILL THE STARTING POINT BE. REGARDING INTENSITY, THE SYSTEM WILL RAPIDLY WEAKEN OVER THE NEXT 24 HOURS OVER LAND, DOWN TO 30-35 KNOTS, THEN MAINTAIN THAT INTENSITY THROUGH TAU 48 AS IT PASSES OVER SATURATED SOILS AND BRIEFLY OVER THE SOUTHERN PORTION OF THE BONAPARTE GULF. AFTER EMERGING OVER THE WARM INDIAN OCEAN WATERS, THE SYSTEM WILL QUICKLY RECONSOLIDATE AND BEGIN TO INTENSIFY, INCREASING UP TO 75 KNOTS BY TAU 96. BY THAT POINT THE SYSTEM WILL HAVE ACHIEVED AXISYMMETRIZATION, AND WILL BE MOVING THROUGH AN ENVIRONMENT OPTIMIZED FOR RAPID INTENSIFICATION (RI), WHICH IS EXPECTED TO BEGIN NO LATER THAN TAU 06. BY THE END OF THE FORECAST PERIOD, TC 27P IS FORECAST TO ACHIEVE A PEAK INTENSITY OF AT LEAST 115 KNOTS. MODEL DISCUSSION: THE CONSENSUS PACKAGE IS IN GOOD AGREEMENT, WITH MINIMAL (80NM) CROSS-TRACK SPREAD THROUGH TAU 72, AND THE JTWC FORECAST IS POSITIONED NEAR THE CONSENSUS MEAN WITH HIGH CONFIDENCE THROUGH THIS POINT. THE MODELS HAVE MAINTAINED A CONSISTENT PATTERN OVER THE LAST TWO DAYS, WITH THE AI MODELS (EC-AIFS, GDM FNV3 AND THE AI CONSENSUS) BEGINNING TO DEVIATE FROM THE REMAINDER OF THE CONSENSUS TRACKERS AT TAU 72 AND TURNING THE SYSTEM POLEWARD MORE SHARPLY, WHILE THE REMAINDER OF THE GUIDANCE CONTINUES ALONG A WEST-SOUTHWESTWARD TRAJECTORY. IF ANYTHING, THE TREND HAS INCREASED WITH THIS RUN, AS THE AI MEMBERS NOW DEPICT A LANDFALL AS FAR EAST AS DAMPIER, THEN TRACK THE SYSTEM WELL INLAND TO THE EAST OF LEARMONTH. HOWEVER, THE UKMET AND GALWEM HAVE NOW SHIFTED SIGNIFICANTLY EASTWARD TOWARDS THE AI MODELS, THOUGH EVERY OTHER MODEL (GFS, ECMWF, THE ENSEMBLE MEANS, ETC.) REMAIN FIRMLY ENTRENCHED ON A SOUTHWESTWARD TRACK, WELL OFFSHORE TO THE NORTHWEST OF LEARMONTH. CROSS-TRACK SPREAD INCREASES TO 350NM BY TAU 120, BETWEEN THE ECMWF ON THE NORTHWESTERN EDGE AND THE EC-AIFS ON THE SOUTHEASTERN EDGE OF THE ENVELOPE. THE JTWC TRACK FROM TAU 72 ONWARDS IS PLACED NEAR THE UPDATED CONSENSUS (TES1) AND THE GALWEM-UKMET COMBO, WITH MEDIUM CONFIDENCE. INTENSITY GUIDANCE IS IN GOOD AGREEMENT ON THE OVERALL TREND, SUPPORTING RAPID WEAKENING TO MINIMAL TROPICAL STORM STRENGTH BY TAU 24, AND THEN RI AFTER TAU 72. THE PEAK INTENSITY IN THE LONG-RANGE FORECAST RANGES BETWEEN 105-140 KNOTS. THE JTWC FORECAST IS PLACED NEAR THE ECWMF AND COAMPS-TC SOLUTIONS, WITH MEDIUM CONFIDENCE. FORECAST CONFIDENCE: TRACK 00-72 HR: HIGH TRACK 72-120 HR: MEDIUM INTENSITY 00-72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN