WDPN33 PGTW 241500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 19W (ATSANI) WARNING NR 009// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 16.7N 138.3E INITIAL INTENSITY: 30 KTS GEOGRAPHIC REFERENCE: 514 NM SOUTH-SOUTHWEST OF IWO TO MOVEMENT PAST 6 HOURS: NORTH-NORTHEASTWARD AT 06 KTS SIGNIFICANT WAVE HEIGHT: 12 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL DEPRESSION (TD) 19W (ATSANI) WITH A NEARLY FULLY EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) WITH A RECENT CONVECTIVE FLARE-UP ALONG THE SOUTHWESTERN PERIPHERY. THE SYSTEM HAS SLOWED DOWN OVER THE LAST 6 HOURS, WHILE A SUBTROPICAL RIDGE (STR) CENTERED TO THE NORTHEAST ASSUMED PRIMARY STEERING. CONSEQUENTLY, A NORTHWARD TRANSLATION VECTOR IS INITIATING TO DOMINATE THE DIRECTION OF MOTION. A BINARY FUJIWHARA INTERACTION REMAINS ACTIVE AS THE DISTANCE BETWEEN TD 19W AND TYPHOON (TY) 17W REMAINS WITHIN THE CRITICAL DISTANCE THRESHOLD. HIGH CONFIDENCE ENVELOPS THE INITIAL POSITION COORDINATES, DEDUCED VIA SHORTWAVE INFRARED IMAGERY DEPICTING THE NEARLY FULLY UNVEILED LLCC. THE METEOROLOGICAL ENVIRONMENT REMAINS MARGINALLY UNFAVORABLE FOR FURTHER INTENSIFICATION. ALTHOUGH SEA SURFACE TEMPERATURES (SST) REMAIN VERY WARM (29-30 C), THE EQUATORWARD OUTFLOW CHANNEL PROVIDES MINIMAL ASSISTANCE. SIMULTANEOUSLY, HIGH (25-30 KTS) NORTHEASTERLY VERTICAL WIND SHEAR (VWS) ARRESTS ANY CENTRAL CONVECTIVE STRUCTURING. MOREOVER, ALTHOUGH TROPOSPHERIC MOISTURE PERSISTS TO THE WEST, UNFAVORABLE MID-LEVEL DRY-AIR ADVECTION CONTINUES TO WRAP AROUND AND INTO THE INNER VORTEX CORE. THE INITIAL INTENSITY OF 30 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON A 241144Z METOP-C ASCAT PASS SHOWING WIND SPEED MAXIMA OF 25 KTS, WITH VERY FEW 30 KTS WIND BARBS. ADDITIONALLY, AGENCY DVORAK ESTIMATES ARE IN PERFECT T2.0 AGREEMENT. INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND RADII). CURRENT STEERING MECHANISM: SOUTHEASTWARD EXTENSION OF A SUBTROPICAL RIDGE CENTERED TO THE NORTHEAST AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T2.0 - 30 KTS RJTD: T2.0 - 30 KTS RCTP: T2.0 - 30 KTS KNES: T2.0 - 30 KTS CIMSS ADT: 31 KTS AT 241210Z CIMSS AIDT: 34 KTS AT 241210Z CIMSS D-MINT: 33 KTS AT 241133Z CIMSS D-PRINT: 26 KTS AT 241210Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY UNFAVORABLE VWS: 25-30 KTS SST: 29-30 CELSIUS OUTFLOW: WEAK EQUATORWARD OTHER FACTORS: PERSISTENT DRY AIR ENTRAINMENT ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: HIGH INITIAL WIND RADII: NOT APPLICABLE 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TD 19W IS FORECAST TO BEGIN TURNING NORTHWARD AND EVENTUALLY NORTHWESTWARD OVER THE NEXT 12 TO 24 HOURS, ULTIMATELY RETREATING INTO THE HIGHLY SHEARED WAKE OF TYPHOON 17W. THIS EVOLUTION MARKS THE ONSET OF THE TERMINAL WEAKENING OF TD ATSANI, DICTATED BY INCREASINGLY HOSTILE NORTHEASTERLY VWS AND RELENTLESS CORE DRY-AIR ENTRAINMENT. CONSEQUENTLY, THE SYSTEM WILL SUSTAIN 30 KTS ONLY TRANSIENTLY. STRUCTURAL DEGRADATION WILL BE RAPID AS THE LLCC LOSES ITS SYMMETRIC DYNAMICS AND OPENS UP, PARTICULARLY ACROSS THE WESTERN SEMICIRCLE. COMPLETE DISSIPATION OVER WATER IS PROJECTED BY TAU 36. MODEL DISCUSSION: NUMERICAL MODEL TRACK PREDICTION SPREAD EXHIBITS HIGH CONSISTENCY, DEPICTING A TIGHT 90 NM CROSS-TRACK DISPERSION ENVELOPE THROUGH TAU 36. ALONG-TRACK UNCERTAINTY IS MODERATE, CONSTRAINED TO A 190 NM SPREAD SEPARATING THE FASTEST JGSM AND DETERMINISTIC ECMWF TRACKERS AND THE SLOWEST UKMET AND ECMWF ENSEMBLE PREDICTIONS. THE OFFICIAL JTWC TRACK FORECAST IS POSITIONED ALONG THE EASTERN BOUNDARY OF THE MULTI-MODEL ENVELOPE WITH HIGH CONFIDENCE, OFFSETTING THE SLOWEST UKMET SOLUTION. INTENSITY FORECAST CONSENSUS REMAINS ALIGNED ON CONTINUOUS DECAY AND DISSIPATION BETWEEN TAU 24 AND TAU 36. PREVIOUS COAMPS-TC SOLUTIONS PROJECTION OF AN ANOMALOUS INTENSIFICATION TO 50-55 KTS HAS DISSIPATED, SOLIDIFYING HIGH CONFIDENCE IN THE TERMINAL WEAKENING OUTLOOK. FORECAST CONFIDENCE: TRACK 00-72 HR: HIGH INTENSITY 00-72 HR: HIGH// NNNN