WDPN33 PGTW 130300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 16W (SIXTEEN) WARNING NR 002// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 21.7N 138.5E INITIAL INTENSITY: 25 KTS GEOGRAPHIC REFERENCE: 242 NM SOUTHWEST OF IWO TO MOVEMENT PAST 6 HOURS: EAST-NORTHEASTWARD AT 02 KTS SIGNIFICANT WAVE HEIGHT: 12 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) CONTINUES TO DEPICT A VERY BROAD LOW LEVEL CIRCULATION (LLC) WITH DISORGANIZED FLARING CONVECTION SURROUNDING THE ASSESSED CENTER. A PARTIAL 122156Z SSMIS 89GHZ MICROWAVE IMAGE SHOWED WEAK, FRAGMENTED CONVECTIVE BANDS WRAPPING INTO A FAIRLY WELL-DEFINED LLCC. THE INITIAL POSITION AND INTENSITY ARE BOTH ASSESSED WITH HIGH CONFIDENCE ON A TIMELY 122356Z PARTIAL ASCAT-B PASS WHICH SHOWED THE LLCC JUST EAST OF AN AREA OF CURVED CONVECTION WITH WINDS UP TO 25 KNOTS JUST TO THE SOUTH OF THE CENTER AND EXTENDING OUT ABOUT 75NM FROM THE CENTER TO THE EAST-SOUTHEAST. THE ENVIRONMENT REMAINS MARGINALLY FAVORABLE, WITH LOW VWS, AND WARM SSTS PROVIDING AMPLE ENERGY FOR DEVELOPMENT. THE TWO MITIGATING FACTORS ARE THE BROAD, MONSOON DEPRESSION-ESQUE NATURE OF THE CIRCULATION AND THE LACK OF A GOOD OUTFLOW MECHANISM. THE MAJORITY OF THE OUTFLOW IS RESTRICTED TO THE LOCAL REGION AROUND TD 16W, WITH ONLY A WEAK TAP INTO AN AREA OF ENHANCED EQUATORWARD OUTFLOW REGION TO THE EAST. THE SYSTEM IS DRIFTING EASTWARD IN A WEAK STEERING ENVIRONMENT. INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND RADII). CURRENT STEERING MECHANISM: COMPETING STEERING ENVIRONMENT BETWEEN NEAR EQUATORIAL RIDGE (NER) TO THE SOUTH AND SUBTROPICAL RIDGE (STR) TO THE NORTH. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T1.5 - 25 KTS RJTD: T1.5 - 25 KTS KNES: T1.5 - 25 KTS CIMSS ADT: 29 KTS AT 122330Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE VWS: 0-5 KTS SST: 29-30 CELSIUS OUTFLOW: WEAK RADIAL ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: HIGH INITIAL WIND RADII: NOT APPLICABLE 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: CURRENTLY TRAPPED IN A COMPETING STEERING ENVIRONMENT, STUCK BETWEEN TWO DEEP-LAYER RIDGES; THE SUBTROPICAL RIDGE (STR) SITTING OVER TOKYO AND A NEAR EQUATORIAL RIDGE (NER) LYING TO THE SOUTH OF GUAM AND EXTENDING WEST OVER THE PHILIPPINES. AT PRESENT, THE NER IS IN A SLIGHTLY BETTER POSITION AND WINNING THE STEERING BATTLE, BUT ONLY JUST, PUSHING TD 16W ON A SLOW EAST-NORTHWESTWARD DRIFT. THIS GENERAL MOTION IS EXPECTED TO CONTINUE THROUGH TAU 24, WHEN TD 16W WILL TAKE A SHARP TURN POLEWARD AND THEN WESTWARD AS THE NER BEGINS TO WEAKEN AND THE STR TO THE NORTH ASSUMES THE DOMINANT STEERING ROLE. BY TAU 36 THE SYSTEM IS FORECAST TO HAVE STEADIED UP ON A WEST-NORTHWEST TRACK ALONG THE SOUTHWEST PERIPHERY OF THE STR TO THE NORTH, AND WILL GRADUALLY PICK UP SPEED AS IT HEADS FOR THE NORTHERN RYUKUS. A DYNAMIC 500MB TROUGH IS FORECAST TO PASS BY TO THE NORTH AROUND TAU 96, ERODE THE STEERING RIDGE AND ALLOW FOR TD 14W TO BEGIN ITS RECURVE, TURNING TO THE NORTH BY TAU 120. DUE TO THE BROAD NATURE OF THE SYSTEM, IT WILL REQUIRE A FAIR AMOUNT OF TIME TO CONSOLIDATE AND INTENSIFY AND THIS PROCESS IS MADE ALL THE MORE CHALLENGING BY THE LACK OF A GOOD OUTFLOW CHANNEL TO EXHAUST THE LOW LEVEL INFLOW. IN LIGHT OF THESE LIMITATIONS, INTENSIFICATION IS EXPECTED TO BE SLOW THROUGH THE FIRST COUPLE OF DAYS, ONLY REACHING 50 KNOTS BY TAU 48. AFTER THIS POINT THE SYSTEM SHOULD BE WELL CONSOLIDATED, THOUGH STILL QUITE LARGE, AND IS EXPECTED TO ESTABLISH A POINT SOURCE OR ANTICYCLONE ALOFT, ALLOWING FOR INCREASED OUTFLOW. IT ALSO LOOKS TO ESTABLISH A WEAK POLEWARD OUTFLOW CHANNEL AROUND TAU 72. THE COMBINATION OF CONTINUED LOW VWS, INCREASED OUTFLOW AND WARM SSTS WILL FUEL NEAR-RAPID INTENSIFICATION BETWEEN TAU 48 AND 96, TO A PEAK OF 95 KNOTS, POSSIBLY SLIGHTLY HIGHER. THEREAFTER, UPPER-LEVEL CONVERGENCE SLAMMING THE SYSTEM FROM THE WEST WILL OFFSET LOW VWS AND MODEST POLEWARD OUTFLOW, LEADING TO SLIGHT WEAKENING BY THE END OF THE FORECAST. MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE HAS STARTED TO COME INTO BETTER AGREEMENT WITH THIS MODEL RUN, WITH ALL OF THE CONSENSUS MEMBERS AGREEING ON THE OVERALL TRACK SCENARIO; A SHORT EASTWARD TRACK, SHARP TURN BACK TO THE WEST-NORTHWEST AND ULTIMATE RECURVE BY TAU 120. THERE STILL REMAINS SOME UNCERTAINTY IN THE TIMING OF THE OVER-THE-SHOULDER TURN, WITH NAVGEM NOW TAKING THE TROPHY OF FURTHEST EAST PROGRESSION PRIOR TO THE TURN. AND THERE REMAINS A MODEST AMOUNT OF CROSS-TRACK SPREAD, WHICH INCREASES STEADILY FROM 75NM AT TAU 72 TO 330NM AT TAU 120 BETWEEN THE EXTREME OUTLIERS (AEMN AND JGSM), WHILE THE REMAINDER OF THE MODELS ARE FAIRLY TIGHTLY PACKED IN A 130NM ENVELOPE. ALONG-TRACK SPREAD INCREASES AFTER TAU 72 AS THE MODELS HANDLE THE TIMING OF THE RIDGE EROSION DIFFERENTLY, AND INCREASES TO ABOUT 150NM BY TAU 120. OVERALL TRACK CONFIDENCE HAS INCREASED SINCE THE PREVIOUS FORECAST, BUT REMAINS MEDIUM THROUGH THE PERIOD. NO SIGNIFICANT CHANGE IN THE INTENSITY GUIDANCE IS OBSERVED, WITH ALL TRACKERS INDICATING SLOW INTENSIFICATION TO TAU 48, WITH A FASTER RATE OF INTENSIFICATION THEREAFTER. PEAK INTENSITIES REMAIN BETWEEN 85-105 KNOTS. THE COAMPS-TC ENSEMBLE IS INDICATING A MODEST PROBABILITY (40-50 PERCENT) OF RAPID INTENSIFICATION (RI) BETWEEN ROUGHLY TAUS 48 TO 96, A LARGE JUMP SINCE THE PREVIOUS RUN. THE JTWC FORECAST LIES ALONG THE CONSENSUS MEAN THROUGH MOST OF THE FORECAST AND DEVIATES HIGH AFTER TAU 72, THOUGH REMAINS BELOW THE MOST AGGRESSIVE OF THE RI AIDS. CONFIDENCE IS HIGH IN THE NEAR-TERM FORECAST, TRENDING TO LOW IN THE EXTENDING TAUS. FORECAST CONFIDENCE: TRACK 0 - 72 HR: MEDIUM TRACK 72-120 HR: MEDIUM INTENSITY 0 - 72 HR: HIGH INTENSITY 72-120 HR: LOW// NNNN