WDPS31 PGTW 071500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 30P (MAILA) WARNING NR 011// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 9.7S 156.3E INITIAL INTENSITY: 110 KTS GEOGRAPHIC REFERENCE: 654 NM SOUTH OF KAPINGAMARANGI MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 03 KTS SIGNIFICANT WAVE HEIGHT: 34 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A DISCERNIBLE AND FULLY SYMMETRIC, CENTRAL EYE FEATURE OF TROPICAL CYCLONE (TC) 30P (MAILA), RESULTING IN HIGH CONFIDENCE IN THE INITIAL POSITION ASSESSMENT. THE TEMPERATURE OF THE EYE HAS WARMED SLIGHTLY SINCE THE LAST WARNING OCCURRING BENEATH A PERSISTENT CANOPY OF VERY COLD DEEP CONVECTION WITH CLOUD TOP TEMPERATURES NEAR -83 C. THE SYSTEM HAS UNDERGONE SUBSTANTIAL AXISYMMETRIZATION, RESULTING IN A MORE UNIFORM AND ROBUST EYEWALL STRUCTURE NOW EVIDENT ACROSS ALL QUADRANTS, INDICATING SLOW, BUT STEADY INTENSIFICATION. SYNOPTIC ENVIRONMENT REVEALS LARGELY SUPPORTIVE CONDITIONS, CHARACTERIZED BY LOW (10-15 KTS) VERTICAL WIND SHEAR, AMPLE TROPOSPHERIC MOISTURE CONTENT, AND A WELL-ESTABLISHED, PREDOMINANTLY WESTWARD, UPPER-LEVEL OUTFLOW CHANNEL. THE PRIMARY ANTAGONISTIC FACTOR HOLDING A POTENTIAL FOR HALTING THE INTENSIFICATION RATE IS THE OCEANIC FEEDBACK MECHANISM OF COLD WATER UPWELLING, AS SIMULATED BY THE COUPLED OCEAN-ATMOSPHERE MODELS HAFS AND HWRF. THE COOL WATER POOL DEPICTED BY THOSE NUMERICAL PREDICTIONS IS DEPICTED RIGHT UNDERNEATH THE CURRENTLY FORECAST TRACK. AT THE MOMENT, THE OBSERVED STRUCTURAL IMPROVEMENTS SUGGEST THIS EFFECT IS CURRENTLY NEGLIGIBLE. THE INITIAL INTENSITY OF 110 KTS IS DETERMINED WITH MODERATE CERTAINTY, REFLECTING A CONSENSUS OF AGENCY DVORAK ESTIMATES AND AUTOMATED SATELLITE-BASED ALGORITHMS THAT UNANIMOUSLY INDICATE STRENGTHENING HAS OCCURRED. INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK CURRENT STEERING MECHANISM: DEEP-LAYER SUBTROPICAL RIDGE (STR) TO THE SOUTHWEST AND CENTERED OVER AUSTRALIA AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T6.5 - 127 KTS KNES: T6.5 - 127 KTS ABRF: T6.5 - 127 KTS CIMSS ADT: 124 KTS AT 071130Z CIMSS AIDT: 120 KTS AT 071130Z CIMSS D-PRINT: 122 KTS AT 071300Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 10-15 KTS SST: 24-29 CELSIUS OUTFLOW: MODERATE WESTWARD ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH 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 30P IS PROJECTED TO CONTINUE TRACKING WEST-NORTHWESTWARD OVER THE NEXT 12-24 HOURS, AT VERY SLOW (3-4 KTS) TRANSLATIONAL SPEEDS. SLOW ACCELERATION TOWARD THE WEST-SOUTHWEST UNDER THE STEERING INFLUENCE OF A SUBTROPICAL RIDGE POSITIONED TO ITS SOUTHWEST IS EXPECTED AFTER TAU 24. THIS TRAJECTORY IS EXPECTED TO KEEP TC 30P ON A PATH JUST SOUTH OF THE PAPUAN PENINSULA FOR THE DURATION OF THE FORECAST PERIOD. THE CURRENT INTENSITY ASSESSMENT CONFIDENCE REMAINS LOW DUE TO THE AFOREMENTIONED UPWELLING POTENTIAL. THE COUPLED MODELS DEPICT A REGION OF OCEANIC COLD WAKE (SUB -26C) IN CLOSE PROXIMITY TO THE CURRENT LOW-LEVEL CIRCULATION CENTER AND EXTENDING DIRECTLY IN FRONT OF THE PROJECTED PATH, POTENTIALLY INCREASES THE CHANCES OF HALTED INTENSIFICATION. NEVERTHELESS, THE PERSISTENT STRENGTHENING TREND SUGGESTS THAT EITHER THIS COLD POOL IS LESS EXTENSIVE THAN MODELED, OR THE AMBIENT SEA SURFACE TEMPERATURES ARE WARMER THAN SIMULATED. GIVEN THE OTHERWISE BENIGN ENVIRONMENTAL PARAMETERS, CONTINUED INTENSIFICATION IS ANTICIPATED, WITH A PEAK INTENSITY NEAR 120 KTS PROJECTED BETWEEN TAU 24 AND TAU 36. THEREAFTER, A GRADUAL WEAKENING TREND IS EXPECTED TO COMMENCE DUE TO INCREASING MID-LEVEL VERTICAL WIND SHEAR (FORECAST TO REACH 30-35 KTS AROUND TAU 72) AND THE POTENTIAL FOR INCREASED FRICTIONAL EFFECTS FROM TOPOGRAPHIC INTERACTION WITH THE OWEN STANLEY RANGE. MODEL DISCUSSION: THERE IS ONLY MODERATE CONFIDENCE IN THE NUMERICAL MODEL TRACK GUIDANCE, WHICH IS CENTERED ON THE MULTI-MODEL GUIDANCE ENVELOPE. THIS CONSENSUS REPRESENTS A COMPROMISE BETWEEN THE FASTER GFS AND NAVGEM SOLUTIONS, THE MID-POINT ECMWF ENSEMBLE MEAN, AND THE SLOWER UKMET, GALWEM AND DETERMINISTIC ECMWF TRACKERS. WHILE THERE IS GENERAL AGREEMENT ON THE OVERALL STEERING REGIME AND THE EVOLUTION FROM A WESTWARD TO A WEST-SOUTHWESTWARD TRACK, SIGNIFICANT UNCERTAINTY PERSISTS REGARDING THE TIMING OF THE RATE OF ACCELERATION. AN ADDITIONAL COMPLICATING FACTOR IS THE POTENTIAL FOR TOPOGRAPHIC ALONG-TRACK INTERACTION AND ASSOCIATED WEAKENING, SHOULD THE SYSTEM PROPAGATE CLOSER TO PAPUA NEW GUINEA. REGARDING INTENSITY, A RECENT SHIFT TOWARDS A MORE ROBUST INTENSIFICATION TREND, EVIDENCED BY THE IMPROVED EYEWALL STRUCTURE, IS CORROBORATED BY NEARLY ALL AVAILABLE GUIDANCE. CONFIDENCE IN THE OFFICIAL INTENSITY FORECAST REMAINS LOW DUE TO THE HIGH UNCERTAINTY ASSOCIATED WITH THE LOOMING POTENTIAL IMPACTS OF THE UPWELLING PHENOMENA AND A LARGE ALONG-TRACK SPREAD IN THE MODEL GUIDANCE. FURTHERMORE, THE PERSISTENCE IN THE TRIGGERING OF NUMEROUS RAPID INTENSIFICATION INDICES IN RECENT MODEL CYCLE PROVIDES ADDITIONAL EVIDENCE SUPPORTING A CONTINUED CONSOLIDATION AND INTENSIFICATION TREND. FORECAST CONFIDENCE: TRACK 00-72 HR: MEDIUM TRACK 72-120 HR: MEDIUM INTENSITY 00-72 HR: LOW INTENSITY 72-120 HR: LOW// NNNN