MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 35W (THIRTYFIVE) WARNING NR 20// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL DEPRESSION (TD) 35W (THIRTYFIVE), LOCATED APPROXIMATELY 209 NM SOUTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WEST- NORTHWESTWARD AT 07 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A DETERIORATING SYSTEM, WITH REMNANTS OF A DISSIPATING CENTRAL COLD COVER (CCC) FEATURE OBSCURING THE LLCC. THE INITIAL POSITION IS BASED ON ANALYSIS OF A FEW VISIBLE OUTER FEEDER BANDS WHICH ARE FEEDING INTO THE LLCC, SURFACE OBSERVATIONS FROM THE SURROUNDING REGION AND PAGASA RADAR LOOPS WITH LOW CONFIDENCE. A 290520Z AMSR2 89 GHZ COMPOSITE MICROWAVE IMAGE SHOWS SOME DEEP CONVECTION TO THE NORTHWEST OF THE ASSESSED LLCC, BUT WITH ONLY WEAK CONVECTIVE BANDING IN ALL OTHER QUADRANTS OF THE SYSTEM. THE INITIAL INTENSITY REMAINS DIFFICULT TO ASSESS, ESPECIALLY WITH THE FLARING CONVECTIVE BURSTS OVER THE SYSTEM, HOWEVER, THE INITIAL INTENSITY HAS BEEN DECREASED SLIGHTLY TO 25 KNOTS BASED ON A PGTW DVORAK INTENSITY ESTIMATE OF T1.5 (25 KNOTS) AND THE LACK OF ANY SURFACE OBSERVATIONS OVER 10 KNOTS IN THE REGION. UPPER-LEVEL ANALYSIS INDICATES A FAVORABLE ENVIRONMENT WITH LOW (15-20 KNOTS) VWS, MODERATE TO STRONG DIFFLUENCE ALOFT AND POLEWARD OUTFLOW. TD 35W IS TRACKING WESTWARD UNDER THE STEERING INFLUENCE OF A LOW- TO MID- LEVEL SUBTROPICAL RIDGE (STR) POSITIONED TO THE NORTH. 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. OVER THE NEXT 12 HOURS TD 35W WILL CONTINUE TRACKING GENERALLY WESTWARD, ALONG THE SOUTHERN PERIPHERY OF THE AFOREMENTIONED STR, PASSING ACROSS THE SOUTHERN PORTION OF MINDORO, THEN NORTH OF PALAWAN ISLAND, REEMERGING INTO THE SOUTH CHINA SEA (SCS) BY TAU 24 AS A WEAK DEPRESSION. INTERACTION WITH THE COMPLEX TERRAIN OF THE PHILIPPINE ARCHIPELAGO WILL LIMIT OPPORTUNITIES FOR INTENSIFICATION FOR THE NEXT 12-24 HOURS BUT ONCE THE SYSTEM REEMERGES OVER THE OPEN WATERS OF THE SCS, IT WILL INTENSIFY SLOWLY AS VWS DECREASES. BY TAU 36 THE SYSTEM WILL REACH TROPICAL STORM STRENGTH AND GROW IN OVERALL SIZE AS IT INTERACTS WITH A LARGE AREA OF GALE FORCE WINDS ASSOCIATED WITH A NORTHEAST SURGE EVENT. DUE TO THE COMPETING INFLUENCES OF THE INCREASED SSTS, LOW VWS AND COOLER, DRIER AIR OF THE SURGE EVENT, TD 35W IS EXPECTED TO MAINTAIN INTENSITY AT 35 KNOTS FROM TAU 36 TO TAU 72. THE BULK OF THE NUMERICAL MODEL GUIDANCE SUPPORTS THE JTWC FORECAST TRACK, HOWEVER, NVGI IS THE SOLE NORTHERN OUTLIER, TAKING THE SYSTEM DUE WEST AND DISSIPATING IT BY TAU 36, WHILE AVNI IS THE SOUTHERN OUTLIER, THOUGH IT MAINTAINS THE SAME GENERAL SHAPE OF THE TRACK. ANALYSIS OF AVNI, NVGI AND ECMWF SLP FIELDS SHOW TD 35W TRACKING GENERALLY SOUTHWESTWARD BUT DISSIPATING BY TAU 24, WHEREBY THE MODELS LOSE TRACK OF THE SYSTEM, BUT THEN MERGING WITH INVEST AREA 97W, WEST OF BORNEO, AND REINTENSIFYING. THE OFFICIAL FORECAST MAINTAINS THE SYSTEM AT 35 KNOTS THROUGH THIS PERIOD, AND REFLECTS THE MERGER OF THE TWO SYSTEMS BY TAU 48. WHILE ALL MODELS BUT NVGI AGREE ON THE TRACK OF TD 35W, DUE TO THE POTENTIAL FOR DISSIPATION PLUS POSSIBLE INTERACTION WITH THE SURGE EVENT AND INVEST 97W, THERE IS LOW CONFIDENCE IN THIS PHASE OF THE FORECAST TRACK. C. AFTER TAU 72, TD 35W WILL TURN WESTWARD ALONG WITH SOUTHWESTERN PERIPHERY OF THE STR TO THE NORTHEAST OF LUZON. BY THIS POINT IN THE FORECAST, THE SURGE EVENT WILL HAVE WEAKENED ENOUGH THAT IT WILL HAVE LITTLE IN THE WAY OF FURTHER INFLUENCE ON TD 35W, ALLOWING IT TO CONSOLIDATE TO THE SOUTHEAST OF VIETNAM. INCREASING SSTS, DECREASING VWS AND INCREASING OUTFLOW PROVIDED BY A DEVELOPING UPPER-LEVEL POINT SOURCE, WILL COMBINE TO ALLOW FOR SLOW INTENSIFICATION THROUGH TAU 120. NUMERICAL TRACK GUIDANCE COMES INTO BETTER AGREEMENT BEYOND TAU 72, WITH ALL MODELS AGREEING ON THE TRACK AND VERY LITTLE CROSS-TRACK DIFFERENCES, LENDING HIGH CONFIDENCE IN THE JTWC FORECAST TRACK. HOWEVER, DUE TO THE HIGH UNCERTAINTY IN THE EARLY PORTIONS OF THE FORECAST THERE IS OVERALL LOW CONFIDENCE IN THE TOTALITY OF THE FORECAST TRACK.// NNNN NNNN