WDPN32 PGTW 060300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 06W (KHANUN) WARNING NR 040// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 27.5N 129.5E INITIAL INTENSITY: 55 KTS GEOGRAPHIC REFERENCE: 109 NM NORTHEAST OF KADENA AB MOVEMENT PAST 6 HOURS: SOUTHEASTWARD AT 07 KTS SIGNIFICANT WAVE HEIGHT: 36 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) AND ANIMATED RADAR DATA FROM JMA SHOW THAT TS 06W (KHANUN) TOOK A SHARP DIVE TO THE SOUTHEAST AFTER PASSING JUST NORTH OF TOKUNOSHIMA ISLAND. THE MOST RECENT IMAGERY SUGGEST THE SYSTEM IS NOW TRACKING DUE EAST OR SLIGHTLY EAST-NORTHEAST, BUT ALSO SHOWS DEVELOPMENT OF A SECOND VORTEX THAT LOOKS TO TRACK BETWEEN TOKUNOSHIMA AND WADOMARI ISLANDS. THE RADAR AND MSI ALSO SHOW A VERY TIGHT INNER LOW LEVEL CIRCULATION CENTER (LLCC), SURROUNDED BY A BAND OF MODERATELY INTENSE CONVECTION WHICH EXTENDS FROM THE NORTHWEST QUADRANT TO THE SOUTHEAST QUADRANT AT ABOUT 85-90NM DISTANT. OVER THE PAST FEW HOURS, A SERIES OF MICROWAVE IMAGES AND THE MSI INDICATE CONVECTION HAS INTENSIFIED ALONG THE CONVECTIVE BAND TO THE EAST OF OKINAWA AND IS BEGINNING TO WRAP FURTHER UP THE EAST SIDE. HOWEVER, CIRA ADVECTED LAYER PRECIPITABLE WATER IMAGERY AS WELL AS THE LATEST SOUNDING FROM KAGOSHIMA INDICATE A WELL-ENTRENCHED WEDGE OF DRY AIR IS PUNCHING INTO THE CORE FROM THE NORTHEAST, INHIBITING CONVECTIVE DEVELOPMENT IN THAT SECTOR. A HOT OFF THE PRESSES 052112Z RCM-1 SAR PASS SHOWS A MAXIMUM 1-MIN WIND OF 59 KNOTS IN THE CONVECTIVE BAND TO THE SOUTH, WITH A AN RMW OF 95NM. IN GENERAL, THIS SUPPORTS THE INITIAL INTENSITY WITH HIGH CONFIDENCE, HEDGED SLIGHTLY HIGHER THAN THE BULK OF THE AGENCY DVORAK CURRENT INTENSITY ESTIMATES AND FAR ABOVE THE OBJECTIVE ESTIMATES. THE ENVIRONMENT REMAINS MARGINAL, WITH LOW VWS OFFSET BY MID-LEVEL DRY AIR, LIMITED UPPER-LEVEL OUTFLOW AND WEAK UPWELLING KEEPING SSTS RELATIVELY COOL. THE SYSTEM IS EXHIBITING SOME TROCHOIDAL MOTION BUT OVERALL IS TRACKING TOWARDS THE EAST ALONG THE NORTH SIDE OF A DEEP NEAR EQUATORIAL RIDGE (NER) TO THE SOUTHEAST. INITIAL WIND RADII BASIS: SAR DATA CURRENT STEERING MECHANISM: NORTHERN PERIPHERY OF THE DEEP-LAYER NER TO THE SOUTHEAST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T3.0 - 45 KTS RJTD: T3.5 - 55 KTS KNES: T3.0 - 45 KTS CIMSS ADT: 27 KTS AT 052330Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE VWS: 10-15 KTS SST: 29-30 CELSIUS OUTFLOW: WEAK EQUATORWARD OTHER FACTORS: MID-LEVEL DRY AIR, UPWELLING OF COOLER WATERS. ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: HIGH INITIAL WIND RADII: HIGH 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: THE RECENT DEVELOPMENT OF A SECONDARY VORTEX TO THE WEST OF THE PRIMARY LLCC WILL COMPOUND THE ALREADY ERRATIC AND TROCHOIDAL MOTION EXHIBITED EARLIER TODAY AS THESE TWO VORTICES ESSENTIALLY UNDERGO A SMALL-SCALE FUJIWHARA TYPE INTERACTION. THIS COMPLEX DANCE AND ERRATIC MOTION IS EXPECTED TO CONTINUE FOR THE NEXT 24 TO 36 HOURS AS THE OVERALL LARGER CIRCULATION TRACKS GENERALLY TOWARDS THE EAST. DURING THIS TIMEFRAME THE DIAMETER OF THE CIRCULATION IS FORECAST TO SLOWLY SHRINK AS THE SYSTEM MOVES INTO WARMER WATERS AND AWAY FROM THE INFLUENCE OF LAND BUT OVERALL INTENSITY IS FORECAST TO REMAIN STEADY THROUGH TAU 24. BY TAU 36 THE SYSTEM SLOWS, BECOMING NEARLY QUASI-STATIONARY AS IT ENTERS A WEAK STEERING PATTERN FOR A BRIEF PERIOD OF TIME. BY TAU 48 THE SUBTROPICAL RIDGE (STR) TO THE NORTHEAST WILL ASSUME THE DOMINATE STEERING ROLE AND TS 06W WILL KICK OUT TO THE NORTH-NORTHWEST ALONG THE WESTERN SIDE OF THIS RIDGE. THE SYSTEM BEGINS TO ACCELERATE AFTER TAU 48 AS THE STEERING RIDGE BUILDS AND MOVES WESTWARD, STRENGTHENING THE STEERING GRADIENT. THE CURRENT FORECAST SHIFTS THE TRACK FURTHER TO THE WEST, WITH THE SYSTEM NOW EXPECTED REMAIN OFF THE COAST OF KYUSHU THROUGH THE FORECAST PERIOD. LANDFALL IS NOW EXPECTED NEAR BUSAN, SOUTH KOREA JUST AFTER TAU 96, FOLLOWED BY AN INLAND TRACK OVER EASTERN SOUTH KOREA AND BRIEF EXCURSION BACK OVER WATER JUST EAST OF WONSON, NORTH KOREA BY TAU 120. AFTER TURNING POLEWARD, THE SYSTEM IS FORECAST TO INTENSIFY BACK TO TYPHOON STRENGTH AS IT CROSSES THE DEEP, WARM WATERS OF THE KUROSHIO AND TAPS INTO STRONG POLEWARD OUTFLOW AHEAD OF A UPPER-LEVEL TROUGH PASSING BY TO THE NORTH. SOME SLIGHT WEAKENING IS EXPECTED PRIOR TO LANDFALL IN KOREA DUE TO THE PROXIMITY TO THE RUGGED TERRAIN OF SOUTHWEST KYUSHU AND ENTRAINMENT OF LOW-LEVEL DRY AIR DESCENDING FROM THE ISLAND INTO THE CORE OF THE SYSTEM. BY TAU 120, THE SYSTEM BEGINS EXTRATROPICAL TRANSITION AS IT INTERACTS WITH A 500MB TROUGH AND ASSOCIATED BAROCLINIC ZONE. MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE IS VERY CONSISTENT WITH THE PREVIOUS CYCLE IN OVERALL SHAPE AND MODEL TENDENCIES, THOUGH THE ENTIRE ENVELOPE CONTINUES TO SHIFT WESTWARD WITH EACH SUCCESSIVE RUN. THE NAVGEM AND COAMPS-TC CONTINUE INSISTING ON A TRACKING OVER FAR SOUTHWEST HONSHU AND INTO THE EASTERN SEA OF JAPAN, WHILE THE UKMET AND SHOWS A TRACK OVER CHEJU DO THEN UP TO NEAR PYONGYANG. THE REMAINDER OF THE CONSENSUS MEMBERS ARE CONFINED TO AN ENVELOPE OF 60NM AT TAU 48, WHICH EXPANDS TO 150NM BY TAU 96, ROUGHLY CENTERED ON BUSAN, SOUTH KOREA. OF NOTE, THE GFS HAS CONTINUED TO TREND FURTHER AND FURTHER WEST WITH EACH MODEL RUN AND NOW IS THE LEFT-MOST TRACKER AFTER TAU 72, SHOWING THE CENTER TRACKING OVER SEOUL AND INTO NORTHEAST CHINA BY TAU 120. THE ENTIRE MODEL ENVELOPE EXPANDS TO OVER 800NM BY TAU 120, PROVIDING A HINT AT THE HIGH LEVELS OF UNCERTAINTY IN THE TRACK FORECAST AFTER TAU 72. A SIMILARLY LARGE SPREAD IS EVIDENT IN THE ENSEMBLE MODELS, RESULTING IN LOW CONFIDENCE IN THE JTWC FORECAST AFTER TAU 72. INTENSITY GUIDANCE IS IN GOOD AGREEMENT ON THE OVERALL FORECAST TREND, THOUGH THE BULK OF THE CONSENSUS PEAKS THE SYSTEM AT AROUND 60-65 KNOTS, WITH THE JTWC FORECAST BEING A SHADE HIGHER, HEDGED TOWARDS THE HAFS-A SOLUTION. FORECAST CONFIDENCE: TRACK 0 - 72 HR: MEDIUM TRACK 72-120 HR: LOW INTENSITY 0 - 72 HR: MEDIUM INTENSITY 72-120 HR: LOW// NNNN