WDPN31 PGTW 080900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 06W (MARIA) WARNING NR 006// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 27.8N 144.8E INITIAL INTENSITY: 50 KTS GEOGRAPHIC REFERENCE: 520 NM SOUTH-SOUTHEAST OF YOKOSUKA, JAPAN MOVEMENT PAST 6 HOURS: NORTH-NORTHEASTWARD AT 15 KTS SIGNIFICANT WAVE HEIGHT: 25 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: TROPICAL STORM (TS) 06W (MARIA) CONTINUES TO SLOWLY INTENSIFY WHILE TRACKING POLEWARD TO THE NORTHEAST OF IWO TO. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A COMPACT SYSTEM, WITH WELL-DEFINED LOW-LEVEL BANDING FEATURES WRAPPING INTO AN OBSCURED LOW LEVEL CIRCULATION CENTER (LLCC). DEEP CONVECTIVE CELLS (HOT TOWERS) CAN BE SEEN DEVELOPING ON THE SOUTHERN PERIPHERY AND WRAPPING UP THE EASTERN SIDE OF THE CIRCULATION, BUT HAVE NOT YET BEEN ABLE TO COMPLETELY ENCIRCLE THE SMALL CORE VORTEX. THE LACK OF ANY SIGNIFICANT CONVECTIVE ACTIVITY AND RELATIVELY CLEAR AIR BETRAYS THE PRESENCE OF DRY AIR ACROSS THE MAJORITY OF THE WESTERN HEMISPHERE OF THE SYSTEM. A 080629Z SSMIS 91GHZ IMAGE SHOWS A SMALL INNER CORE, WITH DEEP CONVECTION ACROSS THE SOUTHERN SIDE OF THE VORTEX AND A LOW EMISSIVITY REGION SUGGESTING A NASCENT MICROWAVE EYE. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON ANALYSIS OF THE ANIMATED MSI AND THE AFOREMENTIONED MICROWAVE FIXES. THE INITIAL INTENSITY OF 50 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE AGREEANCE OF ALL SUBJECTIVE AND OBJECTIVE INTENSITY ESTIMATES, WITH THE EXCEPTION OF THE SLIGHTLY HIGHER KNES DVORAK ESTIMATE OF T3.5. ANALYSIS REVEALS A SUPPORTIVE ENVIRONMENT, WITH LOW VWS, STRONG POLEWARD AND EQUATORWARD OUTFLOW AND WARM SSTS. THE SYSTEM IS CURRENTLY TRACKING NORTH-NORTHEASTWARD ALONG THE WESTERN SIDE OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) TO THE EAST. INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: WESTERN SIDE OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) TO THE EAST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T3.0 - 45 KTS RJTD: T3.0 - 45 KTS RCTP: T3.0 - 45 KTS KNES: T3.5 - 55 KTS CIMSS SATCON: 51 KTS AT 080500Z CIMSS ADT: 49 KTS AT 080600Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 5-10 KTS SST: 29-30 CELSIUS OUTFLOW: STRONG POLEWARD AND EQUATORWARD ANALYSIS CONFIDENCE: INITIAL POSITION: MEDIUM INITIAL INTENSITY: HIGH INITIAL WIND RADII: LOW 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TS 06W IS FORECAST TO CONTINUE TRACKING NORTH-NORTHEASTWARD ALONG THE WESTERN SIDE OF THE STR FOR THE NEXT 24 HOURS, BEFORE IT TURNS DUE NORTH AS THE RIDGE PATTERN REORIENTS SLIGHTLY. AN APPROACHING MID-LATITUDE TROUGH, MOVING IN RAPIDLY FROM THE WEST, WILL BREAK DOWN THE RIDGE PATTERN TO THE NORTH AND ALLOW TS 09W TO MAINTAIN A FAIR AMOUNT OF SPEED HEADING NORTHWARD THROUGH TAU 48. HOWEVER, THE TROUGH IS EXPECTED TO START TO FILL AS A ASSOCIATED JET MAX MOVES DOWNSTREAM. THIS WILL CREATE A COL-REGION DUE NORTH OF TS 09W, AND A GENERAL WEAKENING OF THE STEERING PATTERN, ALLOWING THE SYSTEM TO BEGIN SLOWING DOWN AFTER ABOUT TAU 60. THE FILLING TROUGH WILL NOT BE STRONG ENOUGH TO SEDUCE TS 09W POLEWARD BUT THE POST-TROUGH DEEP-LAYER RIDGE WHICH IS EXPECTED TO DEVELOP IN THE SEA OF JAPAN (SOJ) WILL BE. AS THE SOJ RIDGE SLIDES EASTWARD, IT IS EXPECTED TO BUILD ACROSS HOKKAIDO AND CONNECT WITH A LARGE STR POSITIONED NEAR 40N 170E. THIS WILL HAVE THE EFFECT OF BOTH SLOWING TS 09W AND TURNING IT ONTO A MORE WEST-NORTHWESTWARD TRACK AFTER TAU 72. SIGNIFICANT UNCERTAINTY EXISTS IN THE POTENTIAL TRACK OF TS 06W AS GLOBAL MODELS ARE SPLIT BETWEEN A DUE WEST TRACK AND A VERY FAST NORTHEASTWARD TRACK. IN TERMS OF INTENSITY, THE ENVIRONMENT IS OVERALL FAVORABLE FOR INTENSIFICATION, THOUGH THE PROBABILITY OF RAPID INTENSIFICATION HAS LOWERED SINCE THE PREVIOUS RUN. THERE REMAINS THE ISSUE OF THE DRY AIR TO THE WEST AND VORTEX CONSOLIDATION, WHICH IS STILL OCCURRING. THE FORECAST CALLS FOR STEADY, BUT NOT RAPID, INTENSIFICATION TO A PEAK OF 70 KNOTS BY TAU 36, FOLLOWED BY STEADY WEAKENING AS THE SYSTEM MOVES OVER COOLER WATERS, UPPER-LEVEL FLOW BECOMES CONVERGENT OR WEAK AND DRY AIR MOVES IN TO ENCIRCLE THE CORE. MODEL DISCUSSION: TRACK DETERMINISTIC AND ENSEMBLE TRACK GUIDANCE DEPICTS A BIFURCATION SCENARIO, WITH AN 1150NM SPREAD BETWEEN THE OUTLIERS AT TAU 120. THE WESTERN GROUPING OF MODELS (GFS, GEFS, ECMWF ENSEMBLE MEAN, AND THE ECMWF DETERMINISTIC) TURN THE SYSTEM WEST OR NORTHWEST AFTER TAU 60, AND TRACK IT INTO JAPAN. WITHIN THIS GROUP, THE GFS AND GEFS ARE FURTHEST SOUTH NEAR SENDAI, WHILE THE ECMWF IS THE FURTHEST NORTH, TAKING THE TRACK INTO HOKKAIDO BY TAU 120. THE EASTERN GROUP (NAVGEM, UKMET, GALWEM AND THE UKMET ENSEMBLE) MEANWHILE TAKES THE SYSTEM RAPIDLY NORTHEASTWARD AFTER TAU 60, IN A CLASSIC RECURVE SCENARIO. THE KEY FACTOR WILL BE THE STRENGTH OF THE MID-LATITUDE TROUGH AND THE SPEED AT WHICH THE POST-TROUGH RIDGING BUILDS IN ACROSS HOKKAIDO. THE ECMWF HAS SHIFTED SIGNIFICANTLY IN THIS REGARD SINCE THE PREVIOUS FULL RUN, HAVING SHIFTED FROM A NORTHEASTWARD TRACK TO A NORTHWESTWARD TRACK. ADDITIONALLY, THE GFS GROUPING HAS SHIFTED NORTHWARD FROM A TRACK SOUTH OF TOKYO TO NOW CLOSER TO SENDAI. THE COMBINATION LENDS INCREASING CONFIDENCE TO THE WESTERN TRACK SCENARIO, THOUGH CONFIDENCE IS STILL LOW AFTER TAU 72 DUE TO THE LARGE DISAGREEMENT IN THE OVERALL SCENARIO. INTENSITY GUIDANCE ALSO SHOWS A WIDE SPREAD IN POSSIBLE SOLUTIONS. THE RAPID INTENSIFICATION (RI) AIDS CONTINUE TO BE TRIGGERED, SHOWING A PEAK BETWEEN 75 AND 95 KNOTS. BUT THE REMAINDER OF THE CONSENSUS MEMBERS, INCLUDING ALL OF THE MESOSCALE MODELS, SHOW A MUCH WEAKER SYSTEM, PEAKING OUT AROUND 60 KNOTS. THE JTWC FORECAST CLOSELY FOLLOWS THE CONSENSUS MEAN AND SHIPS GUIDANCE IN TERMS OF THE SHAPE OF THE TREND, AND ROUGHLY 5 KNOTS HIGHER THAN THE CONSENSUS MEAN THROUGH THE DURATION OF THE FORECAST PERIOD. SIGNIFICANT DEVIATIONS REMAIN POSSIBLE DUE TO THE COMPACT NATURE OF THE SYSTEM, LEADING TO LOW CONFIDENCE IN THE TRACK FORECAST. FORECAST CONFIDENCE: TRACK 0 - 72 HR: MEDIUM TRACK 72-120 HR: LOW INTENSITY 0 - 72 HR: LOW INTENSITY 72-120 HR: LOW// NNNN