WDPN31 PGTW 280300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 12W (DOLPHIN) WARNING NR 005// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 13.0N 172.8E INITIAL INTENSITY: 60 KTS GEOGRAPHIC REFERENCE: 520 NM SOUTHEAST OF WAKE ISLAND MOVEMENT PAST 6 HOURS: WESTWARD AT 09 KTS SIGNIFICANT WAVE HEIGHT: 25 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A RAPIDLY CONSOLIDATING TROPICAL STORM (TS), DEFINED BY INTENSE VORTICAL HOT TOWERS AS COLD AS -86 DEGREES CELSIUS AND A DIMPLE EMBEDDED WITHIN A MATURING CENTRAL DENSE OVERCAST (CDO). TS 12W MAINTAINS ROBUST POLEWARD AND WESTWARD UPPER-LEVEL OUTFLOW, THOUGH IT REMAINS RESTRICTED ON THE EASTERN SIDE DUE TO THE PRESENCE OF LOW TO MODERATE SOUTHEASTERLY SHEAR IN THE 400-200 MB LAYER. HOWEVER, THE EXPLOSIVE CONVECTION HAS MANAGED TO WRAP INTO THE UPSTREAM SIDE OF THE SHEAR, WHICH INDICATES THAT THE SYSTEM IS SUCCESSFULLY COUNTERACTING THIS SHEAR. A COMPARISON OF THE 271636Z AND 271855Z SSMIS PASSES CONFIRMS THAT THE CORE IS BECOMING ENCLOSED. FURTHERMORE, A 272148Z ASCAT-B IMAGE REVEALS MAXIMUM WINDS OF 40-45 KTS NORTH OF THE LOW-LEVEL CIRCULATION CENTER (LLCC) AND DEVELOPING GALE-FORCE WINDS IN THE SOUTHERN SEMICIRCLE. THE SYSTEM IS TRAVERSING A FAVORABLE ENVIRONMENT, WITH WARM SEA SURFACE TEMPERATURES (SST) OF 29-30 DEGREES CELSIUS AND VERY HIGH OCEAN HEAT CONTENT (OHC) OF 110-120 KJ PER CM2 IN AN ATMOSPHERE OF RICH DEEP-LAYER MOISTURE. THE INITIAL POSITION, PLACED NEAR THE CONVERGENCE POINT OF THE TIGHTLY CURVED SPIRAL BAND, IS ASSESSED WITH MEDIUM CONFIDENCE. THE INITIAL INTENSITY IS RAISED TO 60 KTS WITH MEDIUM CONFIDENCE BASED ON A BLEND OF THE T3.5-4.0 SUBJECTIVE DVORAK FIXES FROM PGTW, PHFO, KNES, AND RJTD AND THE RISING OBJECTIVE ESTIMATES FROM CIMSS RANGING FROM 43 KTS TO 64 KTS. INITIAL WIND RADII BASIS: SCATTEROMETER DATA CURRENT STEERING MECHANISM: SOUTHERN FLANK OF AN EXPANSIVE SUBTROPICAL RIDGE (STR) TO THE NORTH AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T3.5 - 55 KTS RJTD: T3.5 - 55 KTS RCTP: T3.0 - 45 KTS KNES: T4.0 - 65 KTS PHFO: T3.5 - 55 KTS CIMSS SATCON: 64 KTS AT 272110Z CIMSS ADT: 53 KTS AT 280010Z CIMSS AIDT: 43 KTS AT 280010Z CIMSS D-MINT: 64 KTS AT 272253Z CIMSS D-PRINT: 59 KTS AT 280010Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE VWS: 10-15 KTS SST: 29-30 CELSIUS OUTFLOW: MODERATE POLEWARD AND WESTWARD 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: TS 12W HAS TRACKED JUST SOUTH OF DUE WEST, STEERED BY A STR CENTERED NEAR 30N 160E. THE RIDGE IS NOW WEAKENING, RESULTING IN A WEAKER STEERING GRADIENT THAT HAS CAUSED THE STORM'S FORWARD MOTION TO SLOW FROM 15 KTS TO 09 KTS, A SPEED THAT WILL HOLD THROUGH THE FORECAST PERIOD. THE WEAKENING RIDGE WILL ALSO ALLOW TS 12W TO GAIN LATITUDE AND TURN TOWARD THE NORTHWEST AFTER TAU 12. BEYOND TAU 24, A VIGOROUS TROUGH EJECTING FROM THE EASTERN COAST OF HONSHU WILL CAUSE THE STR TO RETREAT, WHICH WILL AID IN A CONTINUED NORTHWESTWARD TRAJECTORY THROUGH THE EXTENDED FORECAST PERIOD. THE UPSTREAM ENVIRONMENT IS STELLAR FOR VERY SIGNIFICANT INTENSIFICATION. TS 12W WILL TRACK OVER EXCEPTIONALLY WARM SST OF 31-32 DEGREES CELSIUS AND HIGH OHC OF 120-150 KJ PER CM2, AND INTO AN ENVIRONMENT OF LOW SHEAR BELOW 10 KTS. GIVEN THAT TS 12W IS NOW FORMING A NASCENT EYEWALL AND HAS ALREADY COMMENCED RAPID INTENSIFICATION, THESE EXCEPTIONAL CONDITIONS WILL FUEL CONTINUED RAPID TO POTENTIALLY EXTREME RAPID INTENSIFICATION (ERI). THE TROPICAL CYCLONE IS ON THE VERGE OF REACHING TYPHOON STRENGTH, AND THE FORECAST CALLS FOR IT TO ACHIEVE SUPER TYPHOON STATUS BY TAU 48. THE ATMOSPHERIC AND OCEANIC CONDITIONS WILL CONTINUE TO BE PHENOMENAL BEYOND TAU 48, BUT THE POTENTIAL FOR EYEWALL REPLACEMENT CYCLES (ERC) WILL INCREASE. THESE ERC EVENTS, THE TIMING OF WHICH IS DIFFICULT TO PREDICT, WILL LEAD TO LESS PREDICTABLE FLUCTUATIONS IN INTENSITY. MODEL DISCUSSION: THE JTWC FORECAST TRACK HAS CHANGED LITTLE. THE TRACK GUIDANCE IS IN GOOD AGREEMENT, SHOWING A CROSS-TRACK SPREAD THAT INCREASES FROM 100 NM AT TAU 48 TO 260 NM AT TAU 120. THE NAVGEM, GALWEM, AND THE UKMET ENSEMBLE MEAN TRACKERS ANCHOR THE POLEWARD SIDE OF THE SPREAD, WHILE THE GFS AND JGSM SOLUTIONS DEFINE THE EQUATORWARD EDGE. THE CORE OF THE GUIDANCE ENVELOPE CONTAINS AN INTERMINGLED CLUSTER OF BOTH AI AND PHYSICS-BASED MODELS. THE FORECAST TRACK IS SET ALONG THIS CORE GROUPING, WHICH PLACES IT SLIGHTLY SOUTH OF THE MULTI-MODEL CONSENSUS. THE INTENSITY AIDS ARE EXTREMELY AGGRESSIVE, AND THE JTWC INTENSITY FORECAST FOLLOWS SUIT. THE HAFS-A, COAMPS-TC, AND EXPERIMENTAL GOOGLE DEEPMIND MODELS DEPICT EXPLOSIVE DEVELOPMENT THROUGH TAU 60. IN FACT, COAMPS-TC PREDICTS A 55-KT INCREASE OVER THE NEXT 24 HOURS. THE INTENSITY FORECAST IS SET ON THE UPPER END OF THE GUIDANCE ENVELOPE BUT REMAINS BELOW THE HIGHEST-END SOLUTIONS. BOTH THE COAMPS-TC AND HAFS-A SOLUTIONS PEAK THE SYSTEM AT 150 KTS AND 160 KTS, RESPECTIVELY. GIVEN THE EXCEPTIONALLY FAVORABLE ENVIRONMENT AHEAD OF THE STORM, THESE NUMBERS ARE WELL WITHIN THE REALM OF POSSIBILITY, AND THE JTWC INTENSITY FORECAST MAY BE CONSERVATIVE. THE RELIABLE AIDS GENERALLY EITHER LEVEL OFF AT NEAR PEAK INTENSITY OR SHOW SOME WEAKENING AFTER TAU 60. FORECAST CONFIDENCE: TRACK 00-72 HR: HIGH TRACK 72-120 HR: MEDIUM INTENSITY 00-72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN