WDPN32 PGTW 192100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 29W (CHAMPI) WARNING NR 022// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 15.4N 136.7E INITIAL INTENSITY: 135 KTS GEOGRAPHIC REFERENCE: 766 NM SOUTH-SOUTHWEST OF CHICHI JIMA MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 11 KTS SIGNIFICANT WAVE HEIGHT: 52 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS SUPER TYPHOON (STY) 29W AS A VIGOROUS SYSTEM BOASTING A SYMMETRICAL EYE MEASURING 18 NM IN DIAMETER WITH AN EYE TEMPERATURE OF +18C. THE BULK OF THE DEEP CONVECTION ALSO RESIDES IN THE EASTERN PERIPHERY, THOUGH NEW SPIRAL BANDS ARE CONTINUOUSLY FORMING IN THE WEST AS WELL. THE 1911Z GMI MICROWAVE SUITE REVEALS THE STORM IS CONTINUING ITS THIRD ERC, DEPICTING A STRENGTHENING AND CONTRACTING OUTER EYEWALL AND A WEAKENING INNER EYEWALL. THE INNER EYEWALL REMAINS STRONG IN THE WESTERN SEMICIRCLE, BUT HAS ERODED AWAY IN THE EASTERN SEMICIRCLE WHERE A PROMINENT DRY SLOT HAS REPLACED IT. ENVIRONMENTAL ANALYSIS REVEALS A FAVORABLE ENVIRONMENT, CHARACTERIZED BY ROBUST DUAL-CHANNEL OUTFLOW, LOW (5-10 KTS) VERTICAL WIND SHEAR (VWS), WARM (29-30 C) SEA SURFACE TEMPERATURES (SST), HIGH (125-150 KJ PER CM SQUARED) OCEAN HEAT CONTENT (OHC). THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE WELL-DEFINED EYE IN ANIMATED EIR. THE INITIAL INTENSITY OF 135 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE AGENCY DVORAK FIXES AND THE CIMSS AUTOMATED INTENSITY ESTIMATES LISTED BELOW. INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: THE SOUTHWESTERN PERIPHERY OF A BUILDING SUBTROPICAL RIDGE (STR) TO THE NORTHEAST AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T7.0 - 140 KTS RJTD: T7.0 - 140 KTS RCTP: T6.5 - 127 KTS CIMSS SATCON: 142 KTS AT 191623Z CIMSS ADT: 132 KTS AT 191900Z CIMSS AIDT: 138 KTS AT 191900Z CIMSS D-MINT: 144 KTS AT 191709Z CIMSS D-PRINT: 138 KTS AT 191900Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE VWS: 5-10 KTS SST: 29-30 CELSIUS OUTFLOW: STRONG DUAL-CHANNEL OTHER FACTORS: ONGOING EYEWALL REPLACEMENT CYCLE (ERC) ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH 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: STY 29W (CHAMPI) IS FORECAST TO CONTINUE TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF THE ELONGATED STR TO ITS NORTH. THE STR WILL CONTINUE TO BUILD THROUGH THE NEXT 36 HOURS, CAUSING 29W TO ACCELERATE SLIGHTLY. AT TAU 24-36 A SHORTWAVE TROUGH IS EXPECTED TO PASS TO THE NORTH OF THE RIDGE, CAUSING A BREAK BETWEEN THE STEERING RIDGE AND A SECOND RIDGE CENTERED OVER CHINA. THIS BREAK WILL NOT HAVE AN IMMEDIATE IMPACT ON CHAMPI'S TRACK MOTION, WHICH IS EXPECTED TO HAVE A NORTHWESTWARD TRAJECTORY THROUGH TAU 60. BY TAU 48, HOWEVER, THE SECOND RIDGE OVER CHINA IS EXPECTED TO RETROGRADE TO OVER MAINLAND SOUTHEAST ASIA, EMPHASIZING THE COL REGION BETWEEN THE RIDGES. SIMULTANEOUSLY, 29W WILL BEGIN TO SLOW ITS FORWARD ADVANCE AND TURN POLEWARD INTO THE WEAKNESS CREATED BY THE PASSING TROUGH. 29W IS EXPECTED TO ROUND THE STR BETWEEN TAU 72-120, CROSSING THE RYUKYU ISLANDS AROUND TAU 96 AND APPROACHING THE RIDGE AXIS NEAR TAU 120. REGARDING INTENSITY, 29W IS EXPECTED TO WEAKEN THROUGH THE NEXT 12 HOURS AS IT COMPLETES THE ERC, WITH MORE PRONOUNCED WEAKENING POSSIBLE AT TAU 6. AFTER TAU 12, 29W IS EXPECTED TO REGAIN INTENSITY AS IT RECOVERS AND THE INNER EYEWALL CONTRACTS, ULTIMATELY REACHING 145 KTS IN 24 HOURS. THE ENVIRONMENT WILL REMAIN HIGHLY FAVORABLE THROUGH TAU 60, WITH LOW VWS, HIGH SSTS, ROBUST DUAL-CHANNEL OUTFLOW THE ENTIRE TIME, SUPPLEMENTED BY OHC INCREASING TO ABOVE 150 KJ PER CM SQUARED BRIEFLY BETWEEN TAU 12-24, AIDING IN 29W REACHING ITS SECOND PEAK. 29W IS FORECAST TO WEAKEN GRADUALLY FOLLOWING TAU 24, AS IT TRACKS OUT OF THE HIGH OHC AND SIGNIFICANT UPWELLING BEGINS TO IMPACT THE SYSTEM. ADDITIONALLY, THE POSSIBILITY FOR SUBSEQUENT ERCS PERSISTS WHILE CHAMPI REMAINS AN INTENSE SYSTEM, WHICH WOULD CAUSE FURTHER UNPREDICTABLE WEAKENING, ESPECIALLY IF IT FAILS TO COMPLETE THE CYCLE. AFTER ABOUT TAU 36, OHC WILL DECREASE TO 100-125KJ PER CM SQUARED AND SSTS WILL DECREASE TO 27-28C. AS A RESULT OF THOSE FACTORS OCCURRING IN CONJUNCTION WITH 29W SLOWING ITS FORWARD TRAJECTORY, THE UPWELLING IS EXPECTED TO BECOME MORE PRONOUNCED. OHC IS FORECAST TO DECREASE TO BELOW 75 KJ PER CM SQUARED BY TAU 48, AND CHAMPI IS EXPECTED TO CROSS THE 26C ISOTHERM NO LATER THAN TAU 120, THOUGH THE UPWELLING WILL LIKELY INTRODUCE WATER COOLER THAN 26C MUCH SOONER. AS A RESULT, 29W IS FORECAST TO WEAKEN RAPIDLY FROM TAU 72-120. MODEL DISCUSSION: DETERMINISTIC MODEL TRACK GUIDANCE IS IN STRONG AGREEMENT THROUGH TAU 48. FOLLOWING TAU 48, MODEL GUIDANCE STRUGGLES TO INTERPRET THE COMPLEX RIDGING LAYOUT. THERE IS A DISTINCT BIFURCATION BETWEEN THE PHYSICS-BASED MODELS AND THE AI-BASED MODELS: THE PHYSICS-BASED MODELS -- INCLUDING GFS, GEFS, ECMWF, ECENS, UKMET, AND GSM -- DEPICT A STRAIGHT RUNNING TRACK THAT PROGRESSES NORTHWESTWARD THROUGH TAU 120, WITH LANDFALLS IN TAIWAN AND CHINA. THE AI-BASED MODELS -- INCLUDING GOOGLE DEEPMIND, AI ECMWF, AND AI ECENS -- DEPICT A RECURVE SCENARIO WHERE 29W CURVES INTO THE WEAKNESS CREATED BY THE SHORTWAVE TROUGH AND TRACKS NORTHEASTWARD TOWARDS JAPAN. THE JTWC FORECAST REFLECTS THE RECURVE SCENARIO. BOTH GFS AND ECMWF DEPICT THE WEAKNESS BETWEEN THE TWO RIDGES AS A DISTINCT BREAK, YET BOTH SHOW 29W FOLLOWING THE LOWER LEVEL FLOW BETWEEN THE TWO RIDGES. THIS SCENARIO IS DEEMED UNLIKELY, DUE TO THE FACT THAT 29W IS FORECAST TO STILL BE A SIGNIFICANT TYPHOON AT THAT TIME AND SHOULD HAVE NO DIFFICULTY PUNCHING THROUGH TO RECURVE AROUND THE DEEP-LAYER STR. THIS TRACK FORECAST PHILOSOPHY IS SUPPORTED BY THE HIGH ACCURACY OF THE AI-BASED MODELS, WHICH HAVE ALREADY PROVEN CORRECT IN A DIFFERENT TYPHOON WITH THE SAME ATMOSPHERIC SETUP. THE JTWC TRACK FORECAST IS PLACED WITH MEDIUM CONFIDENCE FROM TAU 0-72 AND LOW CONFIDENCE FROM TAU 72-120. RELIABLE INTENSITY AIDS ARE IN GOOD AGREEMENT THROUGH TAU 120, THOUGH NONE REGISTER THE ONGOING ERC AND RESULTING INTENSITY DROP. EVEN SO, THE JTWC INTENSITY FORECAST IS PLACED WITH OVERALL MEDIUM CONFIDENCE. FORECAST CONFIDENCE: TRACK 00-72 HR: MEDIUM TRACK 72-120 HR: LOW INTENSITY 00-72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN