WDPN31 PGTW 250300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 33W (THIRTYTHRE) WARNING NR 002// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 10.6N 122.4E INITIAL INTENSITY: 30 KTS GEOGRAPHIC REFERENCE: 254 NM SOUTH-SOUTHEAST OF MANILA, PHILIPPINES MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 15 KTS SIGNIFICANT WAVE HEIGHT: 14 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A RAPIDLY CONSOLIDATING CIRCULATION, WITH PERSISTENT DEEP CONVECTION BEGINNING TO FORM INTO A MORE SYMMETRICAL CENTRAL DENSE OVERCAST (CDO), AS THE SYSTEM PASSED OVER SOUTHERN PANAY ISLAND IT WAS ACCOMPANIED BY AN IMPRESSIVE BURST OF INNER-CORE LIGHTNING, SUGGESTIVE OF RAPID CONSOLIDATION OF THE INNER CORE OF THE SYSTEM. A 242308Z SSMIS 91GHZ MICROWAVE IMAGE REVEALED NASCENT BANDING FEATURES WRAPPING INTO A STILL SOMEWHAT ILL-DEFINED CIRCULATION CENTER, AT LEAST IN THE UPPER-LEVELS. ANIMATED RADAR DATA FROM PAGASA SHOWS THE NASCENT LOW LEVEL CIRCULATION CENTER (LLCC) BECOMING INCREASINGLY DEFINED AS IT PASSES OVER THE FAR SOUTHERN PORTION OF PANAY ISLAND. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE AFOREMENTIONED MICROWAVE IMAGERY AND RADAR DATA. THE INITIAL INTENSITY IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE STRONG AGREEMENT BETWEEN THE SUBJECTIVE AND OBJECTIVE INTENSITY ESTIMATES NOTED BELOW. ENVIRONMENTAL CONDITIONS CONTINUE TO IMPROVE, NO CHARACTERIZED BY LOW DEEP-LAYER EASTERLY SHEAR, WARM SSTS AND STRONG POLEWARD AND EQUATORWARD OUTFLOW. INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND RADII). CURRENT STEERING MECHANISM: SOUTHWESTERN PERIPHERY OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) CENTERED FAR TO THE NORTHEAST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T2.0 - 30 KTS RJTD: T2.0 - 30 KTS KNES: T2.0 - 30 KTS CIMSS ADT: 30 KTS AT 250030Z CIMSS AIDT: 30 KTS AT 250030Z CIMSS D-MINT: 36 KTS AT 242308Z CIMSS D-PRINT: 40 KTS AT 250030Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 5-10 KTS SST: 28-29 CELSIUS OUTFLOW: STRONG POLEWARD AND EQUATORWARD OTHER FACTORS: LAND INTERACTION. 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: HAVING COMPLETED, OR VERY NEARLY COMPLETED, ITS TRAVERSE ACROSS THE CENTRAL PHILIPPINE ISLAND, TROPICAL DEPRESSION (TD) 33W IS SET TO IMMINENTLY MOVE OVER THE RELATIVELY OPEN WATERS OF THE NORTHERN SULU SEA. THE SYSTEM IS THEN EXPECTED TO PASS THROUGH THE LINAPACAN STRAIT NORTH OF PALAWAN AND EMERGE INTO THE SOUTH CHINA SEA (SCS) WITHIN THE NEXT 12 HOURS. CONTINUING NORTHWESTWARD ALONG THE SOUTHWESTERN PERIPHERY OF THE DEEP STR, TD 33W WILL MOVE INTO THE CENTRAL SCS BY TAU 48, WHERE IT WILL BEGIN TO SLOW DOWN AND TURN MORE WESTWARD TO WEST-SOUTHWESTWARD AS IT MOVES INTO A COMPETING STEERING PATTERN, TRAPPED BETWEEN RIDGING TO THE EAST AND WEST AND A WEAKNESS IN THE RIDGE PATTERN TO THE NORTH. AFTER TAU 72, THE SYSTEM SLOWS TO A CRAWL, NEARLY QUASI-STATIONARY, TRAPPED AS IT WILL BE IN THE WEAK AND COMPETING STEERING PATTERN. OVERALL, TD 33W IS EXPECTED TO DRIFT SLOWLY NORTHWESTWARD ALONG THE COAST OF VIETNAM AFTER TAU 72, BUT THERE IS SIGNIFICANT UNCERTAINTY IN THIS PORTION OF THE FORECAST, WITH A POSSIBILITY OF HIGHLY ERRATIC, AND LOOPING MOTION. THE SYSTEM HAS SLOWLY INTENSIFIED OVER THE PAST SIX HOURS, HELD BACK AS IT MOVED OVER THE RUGGED TERRAIN A SERIES OF ISLANDS. NOW THAT IT IS POISED TO MOVE BACK OVER RELATIVELY OPEN WATERS, THE SYSTEM IS PRIMED FOR A FASTER PACE, POTENTIALLY EVEN RAPID, INTENSIFICATION. ONCE GETTING ITS FEET WET AGAIN, THE SYSTEM WILL STILL NEED A BIT OF TIME TO ACHIEVE A VERTICALLY ALIGNED VORTEX, BUT NOW THAT THE SHEAR HAS DROPPED OFF TO JUST 5-10 KNOTS, THIS PROCESS IS EXPECTED TO BE RELATIVELY QUICK. BY THE TIME IT MOVES INTO THE SCS, TD 33W WILL BE A WEAK TROPICAL STORM AND SEVERAL MODELS SUGGEST IT COULD UNDERGO A PERIOD OF RI AFTER TAU 36. THE OFFICIAL FORECAST STOPS JUST SHORT OF RI, THOUGH IF THE CURRENT TREND CONTINUES, THE NEXT FORECAST MAY GO FOR IT. REGARDLESS, THE SYSTEM ONLY HAS ABOUT 48 HOURS OF GOOD CONDITIONS BEFORE IT SLAMS INTO A STRONG NORTHEASTERLY COLD-SURGE AND VERY STRONG (30-35 KNOTS) SOUTHERLY SHEAR GIVES IT A GOOD WHACK ON THE OL NOGGIN. THE RAPID INCREASE IN SHEAR SHORTLY AFTER TAU 48 COULD EVEN LEAD TO DECAPITATION, BUT EVEN IF IT DOES NOT, THE SYSTEM WILL WEAKEN STEADILY BEYOND TAU 48. SHEAR LOOKS TO DECREASE AGAIN AFTER TAU 96, WHICH WILL ALLOW THE SYSTEM TO AT LEAST MAINTAIN ITS INTENSITY AFTER THIS POINT, AND POTENTIALLY REINTENSIFY BY THE END OF THE FORECAST PERIOD. MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE REMAINS IN GOOD AGREEMENT THROUGH TAU 72, WITH ABOUT 75NM OF CROSS-TRACK SPREAD BETWEEN THE GFS ON THE NORTHERN EDGE AND ECMWF ON THE SOUTHERN EDGE BY THIS POINT IN THE FORECAST. IN A NEW DEVELOPMENT SINCE THE PREVIOUS MODEL RUN, ALONG-TRACK SPREAD INCREASES SHARPLY AFTER TAU 48, OPENING UP TO 170NM BY TAU 72, WITH THE ECMWF MOVING OUT WELL-AHEAD OF THE LAGGING GFS. BEYOND TAU 72, THE MODELS DEPICT A FAIRLY SHARP BIFURCATION, WITH THE ECMWF, AND THE ECEPS MEAN TRACKING THE SYSTEM WEST-SOUTHWEST TO THE COAST OF VIETNAM, WHILE THE REMAINDER OF THE GUIDANCE PACKAGE (CONSENSUS, GFS, GEFS, NAVGEM, ECMWF AIFS AND GDM MEAN) TURN THE SYSTEM NORTHWESTWARD AT A VERY SLOW PACE. THE JTWC FORECAST IS PLACED NEAR THE CONSENSUS MEAN THROUGH THE ENTIRE FORECAST PERIOD, WITH HIGH CONFIDENCE IN THE SHORT-TERM, TRENDING TO MEDIUM CONFIDENCE IN THE LONGER-TERM FORECAST. INTENSITY GUIDANCE CONTINUES TO BE IN GOOD AGREEMENT ON THE OVERALL TREND AND TIMING OF THE PEAK INTENSITY, BUT SHOWS ABOUT A 30 KNOT SPREAD (50-80 KNOTS) IN THE ACTUAL PEAK INTENSITY. THE SHIPS-GFS CONTINUES TO BE THE LOWEST OF THE MODELS, WHILE THE HWRF CONTINUES TO BE THE HIGHEST. ADDITIONALLY, SEVERAL RI AIDS ARE TRIPPED INCLUDING RIPA, RIDE, RI70, RI55, RI30 AND RI25 AND THE CIMSS AI-RI IS PREDICTING A 40-50 PERCENT PROBABILITY OF AT LEAST 25-30 KNOTS OF INTENSIFICATION IN THE NEXT 24 HOURS. WHILE THE JTWC FORECAST DOES NOT EXPLICITLY CALL FOR RI AT THIS TIME, THERE IS INCREASING PROBABILITY OF RI OCCURRING WITHIN THE NEXT 24 HOURS, WITH THE SYSTEM POTENTIALLY REACHING A MUCH HIGHER PEAK INTENSITY CLOSER TO THE HWRF SOLUTION (80 KNOTS). THE JTWC FORECAST IS PLACED NEAR THE CONSENSUS MEAN AND CTCX SOLUTIONS, WITH MEDIUM CONFIDENCE. FORECAST CONFIDENCE: TRACK 00-72 HR: HIGH TRACK 72-120 HR: MEDIUM INTENSITY 00-72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN