WDPS31 PGTW 191500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 27P (NARELLE) WARNING NR 007// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 13.6S 145.4E INITIAL INTENSITY: 125 KTS GEOGRAPHIC REFERENCE: 199 NM NORTH OF CAIRNS, AUSTRALIA MOVEMENT PAST 6 HOURS: WESTWARD AT 11 KTS SIGNIFICANT WAVE HEIGHT: 39 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL CYCLONE (TC) 27P (NARELLE) WITH AN INCREASINGLY CLOUD-FILLED AND CONSTRICTING EYE-FEATURE (12 NM IN DIAMETER), POTENTIALLY INDICATING AN EYEWALL REPLACEMENT CYCLE (ERC). IMMEDIATELY ADJACENT TO THE OBSERVABLE EYE ON ANIMATED EIR, CONTINUING DEEP CONVECTION HAS BEEN IDENTIFIED WRAPPING UNIFORMLY AROUND THE LLCC, WITH NOTICEABLE INCREASED PRESSURE ALONG THE SYSTEMS EASTERN PERIPHERY DUE TO MODERATE EASTERLY VERTICAL WIND SHEAR (VWS) BETWEEN 15-20 KTS. ENVIRONMENTAL ANALYSIS HAS REVEALED CONTINUED MOSTLY FAVORABLE CONDITIONS, WITH WARM SEA SURFACE TEMPERATURES (SSTS) BETWEEN 28-29 C, ROBUST RADIAL OUTFLOW ALOFT, AND MODERATE VWS. THE INITIAL POSITION HAS BEEN PLACED WITH HIGH CONFIDENCE BASED ON AN EVIDENT EYE-FEATURE ON ANIMATED EIR SATELLITE IMAGERY. THE INITIAL INTENSITY HAS BEEN ASSESSED WITH HIGH CONFIDENCE BASED ON SUBJECTIVE AGENCY DVORAK ESTIMATES HOLDING AT 127 KTS, CIMSS OBJECTIVE INTENSITY ESTIMATES, AND AN EARLIER 190847Z RCM-1 PASS. INITIAL WIND RADII BASIS: 190847Z RCM-1 SAR DATA CURRENT STEERING MECHANISM: NORTHEASTERN PERIPHERY OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) CENTERED OVER WESTERN AUSTRALIA. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T6.5 - 127 KTS KNES: T6.5 - 127 KTS ABRF: T6.5 - 127 KTS CIMSS SATCON: 146 KTS AT 190841Z CIMSS ADT: 137 KTS AT 191130Z CIMSS AIDT: 132 KTS AT 191130Z CIMSS D-MINT: 128 KTS AT 190839Z CIMSS D-PRINT: 132 KTS AT 191200Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 15-20 KTS SST: 28-29 CELSIUS OUTFLOW: STRONG RADIAL 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 27P IS FORECASTED TO CONTINUE TRACKING GENERALLY WESTWARD THROUGH THE NEXT 72 HOURS, ALONG THE NORTHERN PERIPHERY OF THE DEEP-LAYER STR CENTERED OVER WESTERN AUSTRALIA. FOLLOWING TAU 72, THE WESTERN-MOST EXTENT OF THE STR OVER WESTERN AUSTRALIA IS FORECASTED TO SLIGHTLY WEAKEN AND RETREAT SOUTHEASTWARD, ALLOWING TC 27P TO BEGIN TRACKING WEST-SOUTHWESTWARD UNTIL THE END OF THE FORECAST PERIOD. BY TAU 120, TC NARELLE IS FORECASTED TO TRACK A FEW MILES JUST NORTH OF ADELE ISLAND AS THE TRACK BEGINS TO BECOME SOUTHWESTWARD. REGARDING INTENSITY, TC 27P IS FORECASTED TO BEGIN GRADUALLY WEAKENING OVER THE NEXT 12 HOURS WHILE MAKING AN INITIAL LANDFALL BETWEEN TAU 6 AND TAU 12. AS THE LLCC TRACKS INTO NORTH QUEENSLAND, AUSTRALIA, SURFACE INTENSITIES ARE EXPECTED TO DECREASE TOWARD 95 KTS AS THE SYSTEM COMPETES WITH LAND INTERACTION AND SUSTAINED MODERATE VWS. FOLLOWING INITIAL LANDFALL, A REEMERGENCE OVER OPEN WATER IS FORECASTED BETWEEN TAU 12 AND TAU 24 IN THE EASTERN GULF OF CARPENTARIA WITH A RELATIVELY BROAD LLCC. AS THE SYSTEM TRACKS WESTWARD, THE BROAD LLCC WILL SLOWLY BEGIN TO WRAP TIGHTLY AND UNDERGO A PERIOD OF REINTENSIFICATION TOWARD 80 KTS BY TAU 48. FOLLOWING TAU 48, A SECOND LANDFALL ALONG THE EAST COAST OF THE NORTHERN TERRITORY IS EXPECTED. DURING THIS PERIOD, GRADUAL DECAY IS FORECASTED DUE TO ADDITIONAL FRICTIONAL LAND IMPACTS AND VWS OVER 15 KTS. AS THE SYSTEM TRACKS WESTWARD OVER THE NORTHERN TERRITORY, CONTINUED WEAKENING IS FORECASTED TOWARD 55 KTS BY TAU 72, APPROXIMATELY 105 NM SOUTH-SOUTHEAST OF DARWIN. NEAR TAU 84, TC 27P WILL REEMERGE OVER THE JOSEPH BONAPARTE GULF; HOWEVER, THE SHORT PERIOD OVER OPEN WATER WILL LIMIT CONSIDERABLE REINTENSIFICATION. A FEW HOURS BEFORE TAU 96, TC NARELLE IS EXPECTED TO MAKE A THIRD LANDFALL OVER THE NORTHERN EXTREME OF WESTERN AUSTRALIA AS SURFACE INTENSITIES CONTINUE TO GRADUALLY DECAY TO 45 KTS. BETWEEN TAU 96 AND TAU 120, TC NARELLE WILL ONCE AGAIN REEMERGE OVER OPEN WATER, OFF THE NORTHWEST COAST OF WESTERN AUSTRALIA. DURING THIS PERIOD, GRADUAL REINTENSIFICAITON IS FORECASTED TOWARD 55 KTS BY TAU 120 AS THE ENVIRONMENT IS EXPECTED TO BE FAVORABLE. MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE CONTINUES TO BE IN VERY GOOD AGREEMENT THROUGHOUT THE FORECAST PERIOD, WITH AN IMPROVING CROSS-TRACK SPREAD OF 32 NM MY TAU 72. FOLLOWING TAU 72, THE CROSS-TRACK SPREAD IS EXPECTED TO INCREASE TO 109 NM BY TAU 96 AS THE GFS DETERMINISTIC MODEL TRACKS TC 27P FARTHER WESTWARD AS THE NORTHERN-MOST SOLUTION, WHILE AVAILABLE ARTIFICIAL INTELLIGENCE SOLUTIONS CHARACTERIZE THE SOUTHERN-MOST TRACK JUST NORTH OF ROWLEY SHOALS. THE JTWC TRACK FORECAST HAS BEEN PLACED VERY CLOSE TO THE JTWC MULTI-MODEL CONSENSUS WITH HIGH CONFIDENCE, WHICH LIES SQUARELY BETWEEN GFS AND THE AVAILABLE GOOGLE DEEPMIND SOLUTION. REGARDING INTENSITY, ALL AVAILABLE GUIDANCE ILLUSTRATES A WEAKENING PHASE UNTIL TAU 24. FOLLOWING TAU 24, ALL INTENSITY SOLUTIONS ARE BECOMING INCREASINGLY ALIGNED DURING THE SYSTEMS TREK ACROSS MULTIPLE LANDMASSES AND REGIONS OF OPEN WATER, WITH COAMPS-TC REMAINING AS THE ONLY OUTLIER DURING THE EXPECTED TRACK IN THE WESTERN GULF OF CARPENTARIA. THEREFORE, THE JTWC INTENSITY FORECAST HAS BEEN ASSESSED WITH MEDIUM CONFIDENCE THROUGHOUT THE FORECAST PERIOD AND PLACED JUST ABOVE THE JTWC MULTI-MODEL INTENSITY CONSENSUS. FORECAST CONFIDENCE: TRACK 00-72 HR: HIGH TRACK 72-120 HR: HIGH INTENSITY 00-72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN