WDPN31 PGTW 110900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 09W (NINE) WARNING NR 001// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 28.8N 135.8E INITIAL INTENSITY: 25 KTS GEOGRAPHIC REFERENCE: 437 NM SOUTH-SOUTHWEST OF YOKOSUKA, JAPAN MOVEMENT PAST 6 HOURS: WESTWARD AT 05 KTS SIGNIFICANT WAVE HEIGHT: 12 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A SLOPPY AND DISORGANIZED ROTATION, WITH MULTIPLE AREAS OF CIRCULATION, WITH FLARING DEEP CONVECTION DISPLACED IN A BROAD ARC TO THE SOUTH OF AN EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC). THE INITIAL POSITION IS ASSESSED WITH ONLY MEDIUM CONFIDENCE, WHILE BASED ON A FULLY EXPOSED LLCC, IT IS BECOMING STEADILY ROPED OUT AND DIFFICULT TO TRACK. HIGH RESOLUTION MODEL FIELDS HAVE BEEN HINTING AT DEVELOPMENT OF A SECONDARY CIRCULATION CENTER TO THE SOUTH-SOUTHEAST OF THE PRIMARY LLCC AND A 110624Z SSMIS 37GHZ MICROWAVE IMAGE SEEMS TO BEAR THIS OUT, AS IT SHOWED A NASCENT SECONDARY AREA OF CIRCULATION NEAR 28.1N 137.6E, APPROXIMATELY 110NM TO THE SOUTHEAST OF THE PRIMARY LLCC. ASIDE FROM THE COMPLEXITY OF THE LOW LEVEL CIRCULATION (LLC), THE OVERALL ENVIRONMENT IS MARGINALLY FAVORABLE, WITH WARM (29-30C) SSTS, AND MODERATE TO STRONG POLEWARD OUTFLOW PROVIDED BY A WEAK UPPER-LEVEL ANTICYCLONE JUST TO THE SOUTHEAST. NORTHERLY VERTICAL WIND SHEAR (VWS) ACROSS THE AREA OF THE CIRCULATION IS MODERATE (15-20 KTS), WHICH IS INHIBITING CONSOLIDATION OF THE CORE FOR THE MOMENT, AND KEEPING CONVECTION PUSHED TO THE SOUTH. THE PRIMARY LLCC HAS TRACKED WEST-NORTHWESTWARD OVER THE PREVIOUS DAY, BUT HAS SLOWED AND TURNED TO THE WEST OVER THE PAST SIX HOURS AND LOOKS TO BE TURNING SOUTHWARD AS OF THE 0700Z HOUR, WHILE THE LARGER ROTATION IT IS PART OF CONTINUES MOVING SLOWLY WEST-NORTHWESTWARD ALONG THE WESTERN SIDE OF THE SUBTROPICAL RIDGE (STR) TO THE EAST. INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND RADII). CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) TO THE EAST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T1.5 - 25 KTS RJTD: T2.0 - 30 KTS KNES: T1.5 - 25 KTS FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE VWS: 15-20 KTS SST: 29-30 CELSIUS OUTFLOW: MODERATE EQUATORWARD ANALYSIS CONFIDENCE: INITIAL POSITION: MEDIUM INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: NOT APPLICABLE 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY. FORECAST DISCUSSION: AS DISCUSSED ABOVE, THE DEVELOPMENT OF A SECONDARY CIRCULATION CENTER TO THE SOUTHEAST OF THE PRIMARY LLCC IS ONGOING. HIGH RESOLUTION MODEL FIELDS SUGGEST THIS SECONDARY VORTICITY CENTER WILL RAPIDLY MOVE NORTHWARD, WHILE THE PRIMARY LLCC REMAINS QUASI-STATIONARY OR MOVES EASTWARD, WITH THE TWO AREAS ULTIMATELY MERGING INTO ONE CONSOLIDATED CORE WITHIN THE NEXT 12 TO 24 HOURS. WHILE THIS MERGER AND CONSOLIDATION IS OCCURRING, THE LARGER ROTATION IN WHICH THESE TWO CIRCULATIONS ARE EMBEDDED, WILL MOVE SLOWLY NORTHWARD. AFTER THE CIRCULATION CONSOLIDATES, IT IS FORECAST TO TURN NORTHEAST ALONG THE PERIPHERY OF THE DEEP STR CENTERED TO THE EAST, MAKE LANDFALL ALONG THE IZU PENINSULA PRIOR TO TAU 48, TRACK THROUGH THE TOKYO METRO AREA, AND THEN REEMERGE OVER WATER AROUND TAU 60. THE SYSTEM WILL THEN CONTINUE NORTHEASTWARD ALONG THE NORTHWEST PERIPHERY OF THE STEERING RIDGE, WHILE UNDERGOING EXTRATROPICAL TRANSITION. IN THE NEAR TERM, THE DISORGANIZED NATURE OF THE LOW LEVEL CORE MEANS THAT INTENSIFICATION IS EXPECTED TO BE SLOW THROUGH TAU 12. THE CONSOLIDATION OF THE CORE AROUND TAU 24 IS EXPECTED TO COINCIDE WITH A REDUCTION IN THE VWS AS THE SYSTEM MOVES INTO A REGION UNDER AN UPPER-LEVEL COL REGION, ALLOWING FOR SOME MARGINAL INTENSIFICATION THROUGH TAU 36. AS THE SYSTEM TURNS TOWARDS THE TOKYO REGION AFTER TAU 36, IT WILL BEGIN TO INTERACT WITH A 200MB TROUGH MOVING OVER JAPAN, AND TAP INTO STRONG DIVERGENT EASTWARD OUTFLOW ALOFT, WHICH WILL OFFSET INCREASING VWS AND ALLOW FOR A BURST OF INTENSIFICATION TO NEAR TYPHOON STRENGTH, AS THE SYSTEM PASSES TOKYO. ONCE BACK OVER WATER TD 09W WILL FEEL THE EFFECTS OF STRONG WIND SHEAR AND DECREASING SSTS, AND RAPIDLY WEAKEN WHILE SIMULTANEOUSLY BEGINNING EXTRATROPICAL TRANSITION (ETT). THE SYSTEM IS FORECAST TO BECOME A FULLY EXTRATROPICAL LOW PRIOR TO DISSIPATION, EAST OF THE KURILE ISLANDS. MODEL DISCUSSION: DETERMINISTIC AND ENSEMBLE TRACK GUIDANCE IS IN OVERALL GOOD AGREEMENT ON THE FORECAST TRACK, WITH A 105NM SPREAD AT TAU 48 INCREASING TO WELL OVER 500NM BY THE END OF THE FORECAST PERIOD. HOWEVER, THE GUIDANCE ENVELOPE, WHILE TIGHT, LIES TO THE WEST OF THE JTWC FORECAST TRACK DUE TO THE FORECASTED INTERACTION BETWEEN THE TWO POSSIBLE CIRCULATION CENTERS ASSOCIATED WITH TD 09W AND THE DISPLACEMENT OF THE PRIMARY CIRCULATION THIS INTERACTION WILL CAUSE. THUS THE TRACK LIES ON THE FAR EASTERN EDGE OF THE GUIDANCE ENVELOPE THROUGH THE DURATION OF THE FORECAST, MOST CLOSELY TRACKING THE HWRF SOLUTION. CONFIDENCE IN THE TRACK IS MEDIUM DUE TO THE NEAR-TERM UNCERTAINTY. INTENSITY GUIDANCE IS MIXED, WITH THE DECAY-SHIPS GUIDANCE INDICATING A PEAK OF 30 KNOTS, WHILE THE HWRF SOLUTION FORECASTS A PEAK OF 75 KNOTS AT TAU 48 AND THE CTR1 RAPID INTENSIFICATION AID SHOWING A PEAK OF 90 KNOTS. THE JTWC FORECAST LIES BELOW MOST OF THE GUIDANCE THROUGH TAU 24 BUT SLIGHTLY ABOVE THE CONSENSUS MEAN, BUT BELOW THE AGGRESSIVE HWRF, THROUGH TAU 48. AS THE SYSTEM RAPIDLY DISSIPATES AFTER TAU 48, THE JTWC FORECAST IS CONSISTENT WITH THE CONSENSUS MEAN. CONFIDENCE IS LOW IN THE INTENSITY FORECAST, AS IT HINGES IN LARGE PART ON THE TIMING BETWEEN THE CORE CONSOLIDATION AND 200MB TROUGH INTERACTION. FORECAST CONFIDENCE: TRACK 0 - 72 HR: MEDIUM TRACK 72-120 HR: LOW INTENSITY 0 - 72 HR: MEDIUM INTENSITY 72-120 HR: LOW// NNNN