WDPN31 PGTW 300900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 26W (NALGAE) WARNING NR 014// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 15.4N 117.2E INITIAL INTENSITY: 45 KTS GEOGRAPHIC REFERENCE: 225 NM WEST-NORTHWEST OF MANILA, PHILIPPINES MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 13 KTS SIGNIFICANT WAVE HEIGHT: 22 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: TROPICAL STORM 26W HAS MOVED WEST-SOUTHWEST OVER THE PAST SIX HOURS, AND THE CENTER NOW LIES FIRMLY IN THE SOUTH CHINA SEA, WEST OF THE CENTRAL PHILIPPINE ISLAND OF LUZON. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SUGGEST THE SYSTEM IS STILL RATHER BROAD, DISORGANIZED, WITH FLARING CONVECTION CONFINED TO THE SOUTHWESTERN PERIPHERY OF THE LOW LEVEL CIRCULATION CENTER (LLCC). A 300516Z AMSR2 89 GHZ MICROWAVE IMAGE REVEALS FORMATIVE CONVECTIVE BANDING IN THE NORTHWEST AND SOUTHWESTERN QUADRANTS OF THE LOW LEVEL CIRCULATION (LLC). THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON AN EARLIER 300208Z ASCAT-B IMAGE, WHICH SHOWS AN ELONGATED BUT DEFINED CIRCULATION WITH 40-45 KNOT WIND OVER THE NORTHWESTERN PERIPHERY. THE INITIAL INTENSITY OF 45 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE PGTW, RJTD, KNES DVORAK ESTIMATES AND ASCAT DATA. ENVIRONMENTAL CONDITIONS ARE GENERALLY FAVORABLE, CHARACTERIZED BY LOW (5-10 KNOTS) WARM (28-29C) SSTS AND GOOD POLEWARD AND EQUATORWARD OUTFLOW. INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: DEEP-LAYER STR CENTERED TO THE EAST AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T3.5 - 55 KTS RJTD: T2.5 - 35 KTS KNES: T3.0 - 45 KTS CIMSS SATCON: 45 KTS AT 300454Z CIMSS ADT: 43 KTS AT 300540Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 5-10 KTS SST: 28-29 CELSIUS OUTFLOW: MODERATE POLEWARD AND EQUATORWARD ANALYSIS CONFIDENCE: INITIAL POSITION: MEDIUM INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: MEDIUM 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: OVER THE PAST 12 HOURS, TROPICAL STORM 26W HAS EMERGED INTO THE SOUTH CHINA SEA (SCS) MOVING WEST-SOUTHWEST. THE CURRENT CONVECTIVE STRUCTURE STILL SUGGEST THE LACK OF PROGRESS TOWARD A VERTICALLY STACKED, SYMMETRICAL CORE, THEREFORE THE SYSTEM WILL CONTINUE TO DEVELOP SLOWLY. BY TAU 12, TS 26W WILL BEGIN TO TURN AND TRACK NORTHWESTWARD, AS MODEL GUIDANCE INDICATES THE WESTERN SIDE OF THE STR WILL ERODE AND WEAKEN AHEAD OF AN APPROACHING MID-LATITUDE TROUGH. AFTER TAU 12, TS 26W WILL HOLD STEADY ON A NORTH-NORTHWEST TRACK THROUGH TAU 48, HOWEVER TRACK SPEED IS FORECAST TO BE RATHER SLOW AS THE STEERING GRADIENTS ARE NOT STRONG. ADDITIONALLY, THE SYSTEM IS EXPECTED TO SLOWLY RECONSOLIDATE, AS AN UPPER-LEVEL POINT SOURCE ALOFT IS ANTICIPATED TO DEVELOP ALOFT ALONG WITH THE POSSIBILITY OF INCREASED POLEWARD OUTFLOW BY TAU 36. THESE IMPROVED ENVIRONMENTAL FACTORS WILL ALLOW FOR STEADY INTENSIFICATION TO A PEAK OF 65 TO 70 KNOTS BY TAU 48. HOWEVER, BY TAU 72, THE SYSTEM WILL BE IMPACTED BY COOLING SSTS, INCREASING VERTICAL WIND SHEAR, ALONG WITH DRY AIR ENTRAINMENT WHICH WILL LEAD TO A STEADY WEAKENING TREND THROUGH TAU 120. FURTHERMORE, THE STEERING PATTERN EVOLVES, AS THE STR TO THE EAST BUILDS WESTWARD, ALONG WITH LOWER-LEVEL FLOW OUT OF THE NORTH-NORTHEAST WHICH WILL THEN STEER THE SYSTEM SHARPLY TO THE NORTHWEST AND THEN WEST-NORTHWEST THROUGH TAU 120. MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE REMAINS IN FAIR AGREEMENT, WITH THE PRIMARY OUTLIERS BEING NAVGEM, COMAPS-TC (NAVGEM) ON THE WESTERN EDGE OF THE AIDS ENVELOPE, AND GALWEM ON THE EASTERN EDGE. THE REMAINDER OF THE TRACKERS ARE TIGHTLY GROUPED IN AN ENVELOPE WHICH GRADUALLY EXPANDS TO 110NM AT TAU 72. THEREAFTER, AS THE TRACK GUIDANCE DIVERGES SIGNIFICANTLY BY TAU 120. THE JTWC FORECAST REMAINS CONSISTENT WITH THE PREVIOUS FORECAST, AND LIES JUST WEST AND SOUTH OF THE MULTI-MODEL CONSENSUS MEAN THROUGH THE FORECAST PERIOD WITH MEDIUM CONFIDENCE. INTENSITY GUIDANCE IS IN FAIR AGREEMENT, WITH THE GFS AND HWRF ON THE HIGH END OF THE SPECTRUM WITH A PEAK OF 70-75 KNOTS, WHILE CTCI, COTI REPRESENT THE LOW END OF INTENSITY GUIDANCE. THE JTWC INTENSITY FORECAST IS PLACED WITH MEDIUM CONFIDENCE AND LIES CLOSE TO THE GFS AND HWRF SOLUTIONS, SLIGHTLY ABOVE THE CONSENSUS MEAN. FORECAST CONFIDENCE: TRACK 0 - 72 HR: MEDIUM TRACK 72-120 HR: MEDIUM INTENSITY 0 - 72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN