WDPN32 PGTW 070900 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: 18.6N 147.7E INITIAL INTENSITY: 30 KTS GEOGRAPHIC REFERENCE: 335 NM NORTH-NORTHEAST OF ANDERSEN AFB MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 03 KTS SIGNIFICANT WAVE HEIGHT: 11 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A COMPACT CIRCULATION WITH A PARTIALLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) DRIFTING NORTHWARD INTO THE CLEAR AIR NORTH OF AN AREA OF DEEP FLARING CONVECTION. THE LATEST FRAMES OF VISIBLE IMAGERY BEFORE THE SUN GOES DOWN SHOW ANOTHER FLARE-UP OF CONVECTION DEVELOPING NEAR THE LLCC. HOWEVER, THE EASTERN SIDE OF THE CIRCULATION APPEARS TO BE IMPACTED BY DRY MID-LEVEL AIR AND REMAINS UNCOVERED BY SIGNIFICANT CONVECTIVE ACTIVITY. A 070315Z AMSR2 COLOR-ENHANCED 89GHZ IMAGE DEPICTED WELL-DEFINED BUT SHALLOW BANDING FEATURES WRAPPING INTO THE LLCC, WITH DEEP CONVECTION DISPLACED TO THE SOUTH BY LIGHT NORTHEASTERLY SHEAR. ANIMATED WATER VAPOR IMAGERY REVEALS A WEAK TUTT-CELL POSITIONED APPROXIMATELY 400NM TO THE NORTHWEST, AND A MUCH STRONGER TUTT-CELL LOCATED APPROXIMATELY 950NM TO THE EAST. CURRENT UPPER-LEVEL WINDS ARE FLOWING SOUTHWESTWARD BETWEEN THESE TWO TUTT-CELLS, ALTHOUGH THERE IS A SPLIT IN THE FLOW IN THE IMMEDIATELY VICINITY OF TS 16W. OUTFLOW ALOFT IS PREDOMINANTLY EQUATORWARD, BUT THERE IS ALSO A WEAK OUTFLOW CHANNEL PUSHING WESTWARD AND THEN POLEWARD INTO THE TUTT-CELL TO THE NORTHWEST. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE MSI LOOP. THE INITIAL INTENSITY IS ASSESSED WITH MEDIUM CONFIDENCE, CONSISTENT WITH THE PGTW T2.0 FIX. ENVIRONMENTAL CONDITIONS ARE FAVORABLE, WITH THE EXCEPTION OF THE DRY MID-LEVEL AIR ALONG THE EASTERN FLANK AND THE PRONOUNCED VORTEX TILT CURRENTLY SEEN IN THE MSI LOOP AND THE AMSR2 MICROWAVE IMAGERY. INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND RADII). CURRENT STEERING MECHANISM: STEERING IS BEING INFLUENCED BY COMPETING FORCES, SPECIFICALLY THE WESTERN PERIPHERY OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) FAR TO THE NORTHEAST AND THE SOUTHEASTERN FLANK OF A STR CENTERED NEAR OKINAWA. CURRENTLY, THE STRONGER STEERING INFLUENCE IS THE STR TO THE NORTHEAST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T2.0 - 30 KTS RJTD: T1.5 - 25 KTS KNES: T1.5 - 25 KTS CIMSS ADT: 29 KTS AT 070540Z CIMSS AIDT: 33 KTS AT 070540Z CIMSS D-MINT: 26 KTS AT 070314Z CIMSS D-PRINT: 26 KTS AT 070610Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 5-10 KTS SST: 29-30 CELSIUS OUTFLOW: WEAK POLEWARD AND EQUATORWARD ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: MEDIUM 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: TROPICAL STORM (TS) 16W IS FORECAST TO TRACK GENERALLY NORTHWESTWARD FOR THE NEXT 24 HOURS, AND WILL LIKELY CROSS THE FAR NORTHERN PORTION OF THE MARIANAS ISLAND CHAIN AROUND TAU 24. OVER THIS PERIOD, THE STR OVER OKINAWA WILL RECEDE WESTWARD, ALLOWING FOR THE EASTERN STR TO BUILD IN TO THE NORTH OF TS 16W. SLOWLY AND SURELY, THE TRAJECTORY OF TS 16W WILL FLATTEN OUT AND BECOME MORE WESTWARD THROUGH TAU 48 AS THE STR TO THE EAST BUILDS. AFTER TAU 48, THE WESTERN RIDGE IS FORECAST TO MERGE WITH THE RIDGE OF THE NORTHWESTERN PACIFIC, RESULTING IN A STRONG, NORTHEAST-SOUTHWEST ORIENTED RIDGE THAT WILL EXTEND FROM NORTH OF TAIWAN ALL THE WAY TO NEAR 35N 160E. FROM TAU 48 THROUGH THE REMAINDER OF THE FORECAST, TS 16W WILL TRAVEL WEST-SOUTHWESTWARD ALONG THE SOUTH SIDE OF THIS EXTENSIVE RIDGING PATTERN. IN TERMS OF INTENSITY, IN THE NEAR-TERM, THE SYSTEM IS NOT EXPECTED TO INTENSIFY MUCH DUE TO THE PRESENCE OF AN ASYMMETRIC VORTEX, AND THE PRESENCE OF DRY MID-LEVEL AIR IN THE EASTERN QUADRANTS, INHIBITING THE DEVELOPMENT OF UPSHEAR CONVECTION. MOST OF THE GLOBAL AND MESOSCALE MODELS ANTICIPATE A REDUCTION IN THE STRENGTH OF THE UPPER-LEVEL FLOW AS THE TUTT-CELL TO THE WEST MOVES AWAY, FURTHER TO THE WEST OVER THE NEXT 48 HOURS. THIS SHOULD ALLOW FOR THE SYSTEM TO SLOWLY CONSOLIDATE AND BEGIN TO ALIGN VERTICALLY. AFTER TAU 48, UPPER-LEVEL NORTHEASTERLY FLOW IS EXPECTED TO INCREASE, BUT BY THEN THE VORTEX SHOULD BE STRONG ENOUGH TO RESIST, AND THE INCREASED EQUATORWARD OUTFLOW WILL SUPPORT THE START OF RAPID INTENSIFICATION AS THE SYSTEM MOVES OVER A POOL OF HIGH OHC WATERS. ENVIRONMENTAL FLOW DECREASES AGAIN AFTER TAU 72, WITH SHEAR VALUES DROPPING OFF, ALLOWING TS 16W TO CONTINUE INTENSIFYING THROUGH THE END OF THE FORECAST, REACHING A PEAK OF AT LEAST 110 KNOTS, AND POTENTIALLY SIGNIFICANTLY HIGHER BY TAU 120. MODEL DISCUSSION: THE DETERMINISTIC GUIDANCE PACKAGE IS IN GOOD AGREEMENT ON THE OVERALL TRACK SCENARIO AND GENERAL SHAPE OF THE TRAJECTORY. HOWEVER, CROSS-TRACK UNCERTAINTY IS MODERATE EVEN AS EARLY AS TAU 72, WITH THE SPREAD OPENING UP TO 160NM BETWEEN THE EGRR ON THE RIGHT AND THE GFS AND GEFS ON THE LEFT. TRACK SPREAD, BOTH ALONG- AND CROSS-TRACK, CONTINUES TO INCREASE THROUGH THE END OF THE FORECAST, OPENING UP TO 300NM AND 260NM RESPECTIVELY. THE UKMET ENSEMBLE IS BY FAR THE FASTEST MODEL, PUSHING OUT WEST OF ALL THE OTHER MEMBERS OF THE CONSENSUS, WHILE THE GFS LAGS FURTHER BEHIND THE OTHERS. BY TAU 120, THE ECMWF DETERMINISTIC AND THE NAVGEM, BOTH SHIFT THE SYSTEM NORTHWESTWARD, MORE TOWARDS MIYAKOJIMA, WHILE THE GFS-GEFS ARE ON A FLATTER WESTWARD TRAJECTORY SOUTH OF 20N. ENSEMBLE GUIDANCE (GEFS AND ECENS) ARE ALIGNED IN DEPICTING THE OVERALL TRACK TRAJECTORY OF NORTHWEST THEN TURNING WEST, BUT DIFFER IN THE AMOUNT OF UNCERTAINTY, WITH THE ECENS DEPICTING A SIGNIFICANTLY LARGER AMOUNT OF CROSS-TRACK UNCERTAINTY THAN THE GEFS. THE ECENS ENVELOPE IS ROUGHLY BETWEEN 18N TO 26N, WHILE THE GEFS IS 18N-23N. THE ECMWF-AIFS IS ALSO POSITIONED ON THE SOUTHERN EDGE OF THE GUIDANCE ENVELOPE, ALONG WITH SOME OF THE OTHER AI MODELS. THE JTWC FORECAST IS POSITIONED ON THE SOUTHERN SIDE OF THE GUIDANCE ENVELOPE, SOUTH OF THE CONSENSUS MEAN, AND CLOSE TO THE GEFS MEAN AND EC-AIFS TRACKER. INTENSITY GUIDANCE IS ALSO IN GENERAL AGREEMENT ON A SLOW RATE OF INTENSIFICATION IN THE NEAR-TERM FOLLOWED BY MORE RAPID INTENSIFICATION LATER IN THE FORECAST, BUT ALSO SHOWS A SIGNIFICANT AMOUNT OF UNCERTAINTY. THE HAFS-A, HWRF, AND COAMPS-TC (GFS) ARE THE MOST AGGRESSIVE, BUT ALSO MOST RELIABLE, MEMBERS OF THE CONSENSUS AND ARE TIGHTLY GROUPED UP THROUGH TAU 72, WHERE THEY CONTINUE TO SHOW INTENSIFICATION BUT DISAGREE ON THE ULTIMATE PEAK. THE DECAY-SHIPS PACKAGE ALIGNS WITH THE MESOSCALE MODELS UP TO TAU 60 BUT THEN FLATTEN OUT AT 55 KNOTS. ADDITIONALLY, THE RIDE, FRIA AND RICN RI AIDS HAVE TRIPPED, BUT ARE LIKELY A BIT TOO AGGRESSIVE. THE JTWC FORECAST IS PLACED ON THE LOWER END OF THE GUIDANCE UP TO TAU 48, CONSISTENT WITH THE HAFS-A, THOUGH ABOUT 10-15 KNOTS LOWER, HEDGED TOWARDS THE HWRF. PEAK INTENSITIES IN THE HWRF IS 110 KTS, IN THE HAFS-A 125 KTS AND THE CTCX 145 KTS. FORECAST CONFIDENCE: TRACK 00-72 HR: MEDIUM TRACK 72-120 HR: MEDIUM INTENSITY 00-72 HR: MEDIUM INTENSITY 72-120 HR: LOW// NNNN