WDPN31 PGTW 281500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 26W (NALGAE) WARNING NR 007// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 13.1N 125.2E INITIAL INTENSITY: 45 KTS GEOGRAPHIC REFERENCE: 261 NM EAST-SOUTHEAST OF MANILA, PHILIPPINES MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 14 KTS SIGNIFICANT WAVE HEIGHT: 20 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED SATELLITE IMAGERY (MSI) DEPICTS A CONSOLIDATING LOW-LEVEL CIRCULATION WITH DEEP CONVECTIVE BANDING WRAPPING TIGHTLY INTO A DEFINED CENTER. A 281216Z AMSU-B 89GHZ MICROWAVE IMAGE REVEALS DEEP CONVECTIVE BANDING OVER THE SOUTHERN SEMICIRCLE WRAPPING INTO THE NORTHERN QUADRANT WITH FRAGMENTED BANDING OVER THE NORTHERN SEMICIRCLE. DESPITE INTERACTION WITH LAND AND FRICTIONAL EFFECTS, UPPER-LEVEL CONDITIONS HAVE IMPROVED SIGNIFICANTLY WITH RADIAL OUTFLOW DRIVING THE RECENT RAPID CONSOLIDATION AND IMPROVED CONVECTIVE STRUCTURE. BASED ON THE AMSU-B MICROWAVE IMAGE AND A RECENT SCATTEROMETER IMAGE, THERE IS HIGH CONFIDENCE IN THE INITIAL POSITION. THE INITIAL INTENSITY OF 45 KNOTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE PGTW AND KNES DVORAK ESTIMATES AND THE CIMSS ADT ESTIMATE. INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK CURRENT STEERING MECHANISM: DEEP-LAYERED SUBTROPICAL RIDGE (STR) POSITIONED TO THE NORTH AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T3.0 - 45 KTS RJTD: T2.5 - 35 KTS KNES: T3.0 - 45 KTS CIMSS SATCON: 55 KTS AT 281035Z CIMSS ADT: 45 KTS AT 281210Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 0-5 KTS SST: 29-30 CELSIUS OUTFLOW: MODERATE RADIAL ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: HIGH INITIAL WIND RADII: LOW 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TS 26W IS FORECAST TO TRACK WEST-NORTHWESTWARD THROUGH TAU 36 ALONG THE SOUTHERN PERIPHERY OF THE STR. THE SYSTEM WILL SLOWLY INTENSIFY THROUGH TAU 24 AS IT SKIRTS THE SOUTHEASTERN COAST OF LUZON WITH A PEAK INTENSITY OF 55 KNOTS EXPECTED AT TAU 24 THEN A SLIGHT WEAKENING TREND AS THE SYSTEM TRACKS ACROSS THE MANILA REGION. AFTER TAU 36, THE SYSTEM WILL REEMERGE OVER THE SOUTH CHINA SEA AND TRACK POLEWARD ALONG THE WESTERN PERIPHERY OF THE STR TOWARD A BREAK IN THE STR. THIS BREAK IS ASSOCIATED WITH A SERIES OF WEAK SHORTWAVE TROUGHS, WHICH ARE FORECAST TO QUICKLY PROPAGATE OVER EASTERN CHINA WITHIN A ZONAL FLOW PATTERN. THE SHORTWAVE TROUGHS ARE NOT STRONG AND LACK THE DYNAMICS TO INDUCE A TYPICAL RECURVATURE SCENARIO. THE DEVELOPMENT OF A FRESH NORTHEAST SURGE OVER THE EAST CHINA SEA BY TAU 96 WITH STRONG NORTH- NORTHEASTERLY WINDS CHANNELING THROUGH THE TAIWAN STRAIT AND EAST OF TAIWAN WILL FURTHER COMPLICATE THE SITUATION AND IS EXPECTED TO CAUSE TS 26W TO SLOW SIGNIFICANTLY SOUTH TO SOUTHWEST OF TAIWAN WITH POTENTIAL FOR A QUASI-STATIONARY TRACK MOTION. TS 26W WILL LIKELY BEGIN TO WEAKEN AS IT ENCOUNTERS THE MORE STABLE AIR ASSOCIATED WITH THE SURGE EVENT. MODEL DISCUSSION: DETERMINISTIC AND PROBABILISTIC MODEL GUIDANCE CONTINUE TO SHOW A BIFURCATION, HOWEVER, THE MORE ACCURATE GLOBAL MODELS (ECMWF, EEMN, AEMN, JGSM) NOW SUPPORT THE JTWC FORECAST TRACK PHILOSOPHY AND THE LARGE MAJORITY OF THE 280600Z ECMWF (EPS) AND GFS (GEFS) ENSEMBLE SOLUTIONS SHOW A QUASI-STATIONARY OR SLOW WESTWARD TURN TOWARD SOUTHERN CHINA. THE SOLUTIONS THAT DO RECURVE THE SYSTEM NORTHEASTWARD GENERALLY REFLECT A WEAKENING AND DISSIPATION SCENARIO NEAR OR EAST OF TAIWAN. GFS HAS SWITCHED TO A NORTH-NORTHEASTWARD TRACK EAST OF TAIWAN, HOWEVER, IT HAS BEEN VERY ERRATIC FROM RUN TO RUN. INTENSITY GUIDANCE IS IN FAIR AGREEMENT WITH A PEAK INTENSITY (PRE-LANDFALL) RANGING FROM 45 TO 55 KNOTS, AND A REINTENSIFICATION PHASE OVER THE SOUTH CHINA SEA TO A PEAK OF 50-65 KNOTS. FORECAST CONFIDENCE: TRACK 0 - 72 HR: MEDIUM TRACK 72-120 HR: LOW INTENSITY 0 - 72 HR: MEDIUM INTENSITY 72-120 HR: LOW// NNNN