WDXS31 PGTW 021500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 19S (FYTIA) WARNING NR 009// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 22.1S 53.1E INITIAL INTENSITY: 50 KTS GEOGRAPHIC REFERENCE: 156 NM SOUTHWEST OF ST DENIS MOVEMENT PAST 6 HOURS: SOUTH-SOUTHEASTWARD AT 11 KTS SIGNIFICANT WAVE HEIGHT: 19 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL CYCLONE (TC) 19S (FYTIA) AS A COMPACT SYSTEM WITH FLARING CONVECTION DIRECTLY OVER THE LOW-LEVEL CIRCULATION CENTER AND WITHIN THE IMMEDIATE SOUTHWEST QUADRANT. OUTSIDE OF THE PRIMARY CONVECTIVE STRUCTURE, PRESENT DRY AIR HAS BECOME EVIDENT OVER THE LAST 12 HOURS, LIMITING ANY CONVECTIVE DEVELOPMENT THROUGHOUT THE MAJORITY OF THE WESTERN AND NORTHERN SEMICIRCLES. THE ENVIRONMENT HAS REMAINED MARGINALLY FAVORABLE SINCE THE PREVIOUS WARNING, WITH WARM SEA SURFACE TEMPERATURES BETWEEN 27-28 C AND ROBUST POLEWARD OUTFLOW, HOWEVER, MODERATE VERTICAL WIND SHEAR BETWEEN 15-20 KTS AND DRY AIR CONTINUES TO ADD PRESSURE TO THE CYCLONES WESTERN AND NORTHERN QUADRANTS. THE INITIAL POSITION HAS BEEN PLACED WITH MEDIUM CONFIDENCE BASED ON ANIMATED EIR AND EXTRAPOLATION FROM A 021031Z 89 GHZ ATMS MI. THE INITIAL INTENSITY HAS BEEN ASSESSED WITH MEDIUM CONFIDENCE BASED ON CIMSS OBJECTIVE INTENSITY ESTIMATES RANGING FROM 32-45 KTS AND SUBJECTIVE AGENCY DVORAK ESTIMATES STEADY AT 45 KTS. INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: TRANSITION PHASE BETWEEN A NEAR-EQUATORIAL RIDGE CENTERED TO THE NORTH-NORTHWEST AND A SUBTROPICAL RIDGE (STR) CENTERED TO THE EAST-SOUTHEAST AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T3.0 - 45 KTS DEMS: T3.0 - 45 KTS FMEE: T3.0 - 45 KTS CIMSS SATCON: 45 KTS AT 021033Z CIMSS ADT: 39 KTS AT 020900Z CIMSS AIDT: 36 KTS AT 021100Z CIMSS D-MINT: 32 KTS AT 020943Z CIMSS D-PRINT: 44 KTS AT 021130Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE VWS: 15-20 KTS SST: 27-28 CELSIUS OUTFLOW: STRONG POLEWARD ANALYSIS CONFIDENCE: INITIAL POSITION: MEDIUM INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: LOW 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TC 19S IS FORECASTED TO TRACK SOUTHEASTWARD THROUGHOUT THE ENTIRETY OF THE 72 HOUR FORECAST PERIOD, ALONG THE WESTERN PERIPHERY OF THE STR CENTERED DIRECTLY TO THE EAST-SOUTHEAST. DURING THE SYSTEMS RELATIVELY SLOW TRACK SOUTHEASTWARD, TC 19S IS EXPECTED TO BEGIN INTERACTING WITH THE NORTHERN EXTENT OF A JET FINGER FROM A HIGH AMPLITUDE LONGWAVE TROUGH LOCATED DIRECTLY TO THE SOUTH NEAR TAU 36 AND CONTINUE SOUTHEASTWARD UNTIL TAU 72. AS VERTICAL WIND SHEAR BEGINS INCREASING TO UNFAVORABLE VALUES (GREATER THAN 30 KTS) AT TAU 36, DRY-AIR ENTRAINMENT WILL ALSO BEGIN ERODING THE CENTRAL VORTEX WITHIN THE MID-LEVELS. TC INTENSITIES WILL CONTINUE TO WEAKEN AFTER TAU 36 AS THE CYCLONE BECOMES INCREASINGLY SHALLOW IN VERTICAL EXTENT. SURFACE INTENSITIES ARE FORECASTED TO WEAKEN FROM 40 KTS TO 35 KTS BETWEEN TAU 36 AND TAU 72, LARGELY DUE TO SEA SURFACE TEMPERATURES DECREASING TO BELOW 26 C, UNFAVORABLE VERTICAL WIND SHEAR, AND DRY-AIR ENTRAINMENT. DURING THIS PERIOD, TC 19S IS FORECASTED TO BEGIN SUBTROPICAL TRANSITION NEAR TAU 48 WITH SURFACE INTENSITIES AT 40 KTS AND COMPLETE SUBTROPICAL TRANSITION BY TAU 72 NEAR 35 KTS AS THE CYCLONE BECOMES FULLY EMBEDDED WITHIN MID-LATITUDE WESTERLIES. MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE AND ARTIFICIAL INTELLIGENCE (AI) MODEL GUIDANCE CONTINUES TO REMAIN IN GOOD AGREEMENT THROUGHOUT THE 72 HOUR FORECAST PERIOD, WITH A CROSS-TRACK SPREAD OF 60 NM BY TAU 36. FOLLOWING TAU 36, THE CROSS-TRACK SPREAD IS FORECASTED TO GRADUALLY INCREASE TO 87 NM, WITH THE EXCEPTION OF THE GFS DETERMINISTIC SOLUTION. DURING SUBTROPICAL TRANSITION, THE GFS DETERMINISTIC GUIDANCE ILLUSTRATES A SHALLOW VORTEX WITH A WESTWARD TRACK AWAY FROM THE BULK OF JTWC CONSENSUS SOLUTIONS. THE JTWC FORECAST TRACK HAS BEEN PLACED WITH MEDIUM CONFIDENCE THROUGHOUT THE 72 HOUR FORECAST AND ALIGNED CLOSELY WITH THE MULTI-MODEL CONSENSUS AND AI SOLUTIONS. REGARDING INTENSITY, THE MAJORITY OF JTWC INTENSITY CONSENSUS MEMBERS CHARACTERIZE STEADY INTENSITIES THROUGH TAU 12, WITH A WEAKENING TREND THEREAFTER. HAFS-A CONTINUES TO SHOW MODERATE INTENSIFICATION OVER THE NEXT 12 HOURS, HOWEVER, INCREASING DRY AIR AND VERTICAL WIND SHEAR ARE EXPECTED TO LIMIT FURTHER INTENSIFICATION. IN ADDITION, COAMPS-TC EPS INTENSITY GUIDANCE ILLUSTRATES STEADY INTENSITIES TO MODERATE WEAKENING THROUGHOUT THE FORECAST PERIOD. THE JTWC INTENSITY FORECAST HAS BEEN ASSESSED WITH MEDIUM CONFIDENCE, AND ALIGNED CLOSELY TO THE MULTI-MODEL INTENSITY CONSENSUS. FORECAST CONFIDENCE: TRACK 00-72 HR: MEDIUM INTENSITY 00-72 HR: MEDIUM// NNNN