WDPS32 PGTW 012100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 16P (SIXTEEN) WARNING NR 001// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 13.8S 161.9E INITIAL INTENSITY: 40 KTS GEOGRAPHIC REFERENCE: 437 NM WEST-NORTHWEST OF PORT VILA, VANUATU MOVEMENT PAST 6 HOURS: EAST-SOUTHEASTWARD AT 07 KTS SIGNIFICANT WAVE HEIGHT: 18 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: TRAILING APPROXIMATELY 800NM BEHIND TC 15P (JUDY), ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) REVEALS THAT TC 16P HAS TWO PRIMARY CELLS OF PERSISTENT DEEP CONVECTION THAT ARE CONSOLIDATING OVER THE LOW LEVEL CIRCULATION CENTER (LLCC). A FORTUITOUS SUITE OF SSMIS IMAGERY, SPECIFICALLY A 011754Z 89GHZ COLOR COMPOSITE MICROWAVE IMAGE SHOWS CURLING BANDS OF DEEP CONVECTION WRAPPING INTO AN OPEN AND SLIGHTLY ELONGATED LLCC. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON MSI AND SSMIS IMAGERY. THE INITIAL INTENSITY OF 40 KTS IS ASSESSED WITH LOW CONFIDENCE BASED ON AN UNFORTUNATE LACK OF SATELLITE WIND SPEED PRODUCTS COUPLED WITH AGENCY DVORAK INTENSITY ESTIMATES HISTORICALLY TRAILING BEHIND THE FORECAST INTENSITY. THESE ESTIMATES OR LACK THEREOF ARE COUNTERED BY PERSISTENT RAPID INTENSIFICATION (RI) AIDS AND A SIGNIFICANTLY IMPROVED AND TIGHTER CONVECTIVE STRUCTURES AND BANDING FEATURES. INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: TRANSITIONING STEERING INFLUENCE FROM A NEAR EQUITORIAL RIDGE (NER) TO A SUB-TROPICAL RIDGE (STR) TO THE EAST-SOUTHEAST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T2.5 - 35 KTS KNES: T1.0 - 25 KTS PHFO: T2.0 - 30 KTS FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 10-15 KTS SST: 30-31 CELSIUS OUTFLOW: STRONG RADIAL OTHER FACTORS: UPPER-LEVEL POINT SOURCE PROVIDING VIGEROUS OUTFLOW. ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: LOW INITIAL WIND RADII: LOW 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY. FORECAST DISCUSSION: TC 16P IS FORECAST TO LARGELY MIMIC THE TRACK OF TC 15P (JUDY). AS THE SYSTEM CONTINUES TO TRANSITION ITS STEERING INFLUENCE TO THE STR TO THE EAST-SOUTHEAST IT WILL CONTINUE TRACKING GENERALLY SOUTHEASTWARD OVER THE NEXT 48 HOURS. DURING THIS TIME, THE SYSTEM WILL BE IN A FAVORABLE ENVIRONMENT CHARACTERIZED BY WARM SEA SURFACE TEMPERATURES AND VIGOROUS OUTFLOW ALOFT SLIGHTLY OFFSET BY MODERATE VERTICAL WINDS SHEAR. THESE FACTORS ARE FORECAST TO STRENGTHEN 16P TO 90 KTS AND POSSIBLY HIGHER BY TAU 48. AS 16P CONTINUES POLEWARD OF THE STR NEAR TAU 72, VERTICAL WIND SHEAR BEGINS TO CLIMB, DRY AIR ENTRAINMENT INCREASES AND THE SYSTEM PASSES SOUTH OF THE 26 C ISOTHERM, THESE FACTORS HERALD THE START OF SUB-TROPICAL TRANSITION (STT). OVER THE NEXT 24 HOURS, THESE FACTORS CONTINUE TO INCREASE AND THE SYSTEM FINALLY BEGINS TO WEAKEN THROUGH TAU 96 AFTER WHICH TC 16P IS FORECAST TO BE FULLY SUB-TROPICAL. MODEL DISCUSSION: WITH THE EXCEPTION OF NVGM TO THE NORTH, NUMERICAL MODELS ARE IN GOOD AGREEMENT THAT TC 16P WILL CONTINUE POLEWARD OF THE STR AND COMPLETE STT NEAR TAU 96. FOR THIS REASON THE JTWC FORECAST TRACK IS PLACED WITH HIGH CONFIDENCE. RELIABLE MODEL INTENSITY GUIDANCE IS IN GOOD AGREEMENT THAT TC 16P WILL STEADILY INTENSIFY WITH SEVERAL AIDS INDICATING RAPID INTENSIFICATION THROUGH TAU 48 WITH ALL MEMBERS SHOWING A PEAK INTENSITY NEAR TAU 60 AFTER WHICH STEADY WEAKENING THROUGH THE FORECAST PERIOD. FOR THIS REASON THE JTWC INTENSITY FORECAST IS PLACED WITH MEDIUM CONFIDENCE. FORECAST CONFIDENCE: TRACK 0 - 72 HR: HIGH TRACK 72-120 HR: HIGH INTENSITY 0 - 72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN