WDPN32 PGTW 052100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 05W (DANAS) WARNING NR 008// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 21.1N 118.1E INITIAL INTENSITY: 65 KTS GEOGRAPHIC REFERENCE: 305 NM SOUTHWEST OF TAIPEI, TAIWAN MOVEMENT PAST 6 HOURS: NORTH-NORTHEASTWARD AT 03 KTS SIGNIFICANT WAVE HEIGHT: 24 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TYPHOON 05W (DANAS) WITH COMPACT CORE OF DEEP CONVECTION OBSCURING THE LOW-LEVEL CIRCULATION CENTER (LLCC). BANDS OF DEEP CONVECTION CAN BE SEEN SURROUNDING THE EASTERN PERIPHERY OF THE SYSTEM, EXTENDING DOWN TO THE NORTHWESTERN CORNER OF LUZON. THERE IS SOME SLIGHT VORTEX TILT, WITH THE CENTER ASSESSED TO BE WITHIN THE NORTHEASTERN PORTION OF THE DEEP CONVECTION. ENVIRONMENTAL ANALYSIS INDICATES THAT 05W IS IN A HIGHLY FAVORABLE ENVIRONMENT CHARACTERIZED BY STRONG POLEWARD AND EASTWARD OUTFLOW, LOW (5-10 KTS) VERTICAL WIND SHEAR, AND WARM (29-30 C) SEA SURFACE TEMPERATURES. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE TIGHT CIRCULATION IN ANIMATED RADAR IMAGERY. THE INITIAL INTENSITY OF 65 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE AGENCY DVORAK AND OBJECTIVE INTENSITY ESTIMATES LISTED BELOW. INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK CURRENT STEERING MECHANISM: NORTHWESTERN PERIPHERY OF A DEEP LAYER NEAR-EQUATORIAL RIDGE CENTERED TO THE SOUTHEAST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T4.0 - 65 KTS RJTD: T3.0 - 45 KTS RCTP: T3.5 - 55 KTS KNES: T4.5 - 77 KTS DEMS: T3.5 - 55 KTS CIMSS SATCON: 58 KTS AT 051530Z CIMSS ADT: 55 KTS AT 051750Z CIMSS AIDT: 56 KTS AT 051750Z CIMSS DPRINT: 66 KTS AT 051750Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE VWS: 5-10 KTS SST: 29-30 CELSIUS OUTFLOW: STRONG POLEWARD ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: LOW 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: TAUS 24-48 ARE FORECAST TO BE LOWER INTENSITY THAN PREVIOUSLY FORECASTED. FORECAST DISCUSSION: TY 05W IS FORECAST TO CONTINUE TRACKING NORTH-NORTHEASTWARD, ALONG THE NORTHWESTERN PERIPHERY OF THE NEAR-EQUATORIAL RIDGE TO THE SOUTHEAST THROUGH TAU 48. NEAR TAU 48, RIDGING IS FORECAST TO BUILD IN TO THE NORTH OF THE SYSTEM, WHICH WILL INITIATE A SHARP WESTWARD TURN INTO MAINLAND CHINA. 05W WILL THEN CONTINUE ON A GENERALLY WESTWARD TRACK THROUGH THE REMAINDER OF THE FORECAST PERIOD AS IT TRACKS FURTHER INLAND. OF NOTE, THE PASSAGE THROUGH THE TAIWAN STRAIT HAS SHIFTED SLIGHTLY CLOSER TO THE WESTERN COAST OF TAIWAN. REGARDING INTENSITY, 05W IS FORECAST TO CONTINUE INTENSIFYING THROUGH TAU 12-18 AS THE ENVIRONMENT REMAINS HIGHLY CONDUCIVE. HOWEVER, AFTER TAU 18, INTERACTION WITH THE WESTERN COAST OF TAIWAN WILL HINDER DEVELOPMENT AND WEAKEN THE VORTEX. THIS WEAKENING TREND IS FORECAST TO PERSIST THROUGH TAU 48 AS 05W ENTERS A POOL OF COOL WATER THAT EXTENDS SOUTHWARD, TO AROUND 28N, AND EASTERLY SHEAR INCREASES. AFTER TAU 48, THE RUGGED TERRAIN OF EASTERN CHINA WILL CAUSE 05W TO QUICKLY WEAKEN WITH DISSIPATION FORECAST TO OCCUR NO LATER THAN TAU 96. MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN VERY GOOD AGREEMENT THROUGH TAU 48, WITH A MERE 55 NM CROSS-TRACK SPREAD AT TAU 48. SPREAD THEN INCREASES TO 120 NM AT TAU 72, AS THE SYSTEM TURNS WESTWARD. AFTER TAU 72, MODELS DIVERGE AS THE WEAKENED VORTEX TRAVELS FURTHER INLAND. ONE OUTLIER IS THE GFS DETERMINISTIC, WHICH HAS THE SYSTEM MAKE A SHARP SOUTH-SOUTHWESTWARD TURN AFTER TAU 72. OVERALL, THE JTWC TRACK FORECAST IS PLACED WITH MEDIUM CONFIDENCE THROUGH TAU 72 AND LOW CONFIDENCE THEREAFTER. INTENSITY GUIDANCE IS IN RELATIVELY GOOD AGREEMENT ON INTENSIFICATION THROUGH TAU 12 AND THEN WEAKENING THEREAFTER. THE STATISTICAL DYNAMICAL MODELS ARE THE MAIN OUTLIERS, KEEPING THE SYSTEM TYPHOON STRENGTH THROUGH TAU 60. THE JTWC INTENSITY FORECAST IS PLACED SLIGHTLY BELOW THE MULTI-MODEL CONSENSUS TO OFFSET THE OUTLIERS AND BE MORE IN LINE WITH THE MAIN GROUPING. CONFIDENCE IS LOW DUE TO THE POSSIBILITY FOR MORE OR LESS LAND INTERACTION WITH WESTERN TAIWAN, WHICH COULD HEAVILY AFFECT INTENSITIES. FORECAST CONFIDENCE: TRACK 0 - 72 HR: MEDIUM TRACK 72-120 HR: LOW INTENSITY 0 - 72 HR: LOW INTENSITY 72-120 HR: LOW// NNNN