WDPN32 PGTW 160300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 29W (CHAMPI) WARNING NR 007// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 11.3N 154.0E INITIAL INTENSITY: 45 KTS GEOGRAPHIC REFERENCE: 565 NM EAST-SOUTHEAST OF NAVSTA GUAM MOVEMENT PAST 6 HOURS: WESTWARD AT 21 KTS SIGNIFICANT WAVE HEIGHT: 18 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL STORM (TS) 29W (CHAMPI) FIGHTING THE VERTICAL WIND SHEAR (VWS) AS IT ATTEMPTS TO EXPAND ITS UPPER-LEVEL CLOUD CANOPY TO THE EAST. THOUGH THE UPPER-LEVEL CONVECTION COMPLETELY OBSCURES THE LOW-LEVEL CIRCULATION, A SERIES OF MICROWAVE PASSES RANGING FROM 151651Z TO 152038Z DEPICT THE SYSTEM MAKING A QUICK, UNEXPECTED DETOUR JUST SOUTH OF DUE WESTWARD. ANALYSIS OF ANIMATED SATELLITE IMAGERY AND THE 152259Z ASCAT DATA SUPPORT THE ARGUMENT THAT 29W RECENTLY RETURNED TO ITS EXPECTED WEST-NORTHWESTWARD TRACK, WHICH IT IS FORECAST TO MAINTAIN. ENVIRONMENTAL ANALYSIS REVEALS A FAVORABLE ENVIRONMENT, CHARACTERIZED BY LOW TO MODERATE (15-20 KTS) VWS, WARM (29-30 C) SEA SURFACE TEMPERATURES (SST), GOOD (75-100 KJ PER CM SQUARED) OCEAN HEAT CONTENT (OHC), AND MODERATE WESTWARD OUTFLOW. THE INITIAL POSITION AND INTENSITY ARE ASSESSED WITH HIGH CONFIDENCE BASED ON THE 152259Z ASCAT IMAGERY. INITIAL WIND RADII BASIS: 152259Z ASCAT DATA CURRENT STEERING MECHANISM: THE SOUTHERN PERIPHERY OF THE SUBTROPICAL RIDGE (STR) CENTERED TO THE NORTH AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T3.0 - 45 KTS RJTD: T2.5 - 35 KTS RCTP: T2.5 - 35 KTS CIMSS ADT: 57 KTS AT 152340Z CIMSS AIDT: 48 KTS AT 152340Z CIMSS D-MINT: 37 KTS AT 152214Z CIMSS D-PRINT: 36 KTS AT 152340Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 15-20 KTS SST: 29-30 CELSIUS OUTFLOW: MODERATE WESTWARD ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: HIGH INITIAL WIND RADII: HIGH 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TS 29W (CHAMPI) IS FORECAST TO CONTINUE STEADILY TRACKING WEST-NORTHWESTWARD THROUGH TAU 36 WHILE IT REMAINS ON THE SOUTHERN PERIPHERY OF THE STEERING STR CENTERED FAR TO THE NORTH. AT ABOUT TAU 24, A DEEP-LAYER TROUGH IS EXPECTED TO PASS TO THE NORTH, WEAKENING THE RIDGE AND FORCING IT TO RETREAT EASTWARD. SIMULTANEOUSLY, A SECOND STR IS EXPECTED TO BUILD IMMEDIATELY FOLLOWING THE PASSAGE OF THE TROUGH AND ASSUMING STEERING INFLUENCE OVER 29W FROM TAU 36-120. IT IS EXPECTED TO BE A SMOOTH TRANSITION FROM ONE STR TO THE OTHER, AND THE NEW STEERING ENVIRONMENT WILL MAINTAIN THE STEADY WEST-NORTHWESTWARD TRACK FOR THE REMAINDER OF THE FORECAST PERIOD. REGARDING INTENSITY, 29W IS FORECAST TO STEADILY INTENSIFY THROUGH TAU 12 WHILE THE SYSTEM CONTINUES TO CONSOLIDATE AND ORGANIZE. BEGINNING AT TAU 12 AND LASTING UNTIL TAU 60, 29W IS FORECAST TO RAPIDLY INTENSIFY IN RESPONSE TO THE INCREASINGLY FAVORABLE ENVIRONMENT IT IS EXPECTED TO ENCOUNTER. VWS IS EXPECTED TO REMAIN BETWEEN 10-20 KTS UNTIL TAU 72; HOWEVER, BETWEEN TAU 12-72, THE EQUATORWARD AND WESTWARD OUTFLOW CHANNELS ARE EXPECTED TO STRENGTHEN CONCURRENT WITH CHAMPI TRANSITING THROUGH A REGION OF SLIGHTLY HIGHER (100-125 KJ PER CM SQUARED) OHC. AFTER TAU 60, 29W WILL CONTINUE TO INTENSIFY UNTIL PEAKING AT TAU 96. BETWEEN TAU 72-120, 29W WILL LIKELY MAINTAIN A HIGH INTENSITY, AS ENVIRONMENTAL CONDITIONS WILL CONTINUE TO IMPROVE: VWS IS EXPECTED TO DROP TO LESS THAN 10KTS AFTER TAU 72 AND OHC IS EXPECTED TO INCREASE TO ABOVE 150 KJ PER CM SQUARED. THIS ENVIRONMENT SHOULD HAVE NO ISSUE SUSTAINING A STRONG TYPHOON, HOWEVER, THE POTENTIAL FOR AN EYEWALL REPLACEMENT CYCLE (ERC) INCREASES, AND AT LEAST ONE ERC IS CURRENTLY DEPICTED IN THE HAFS-A MODEL GUIDANCE BETWEEN TAU 72-120. AS A RESULT, THE INTENSITY BETWEEN TAU 72-120 REMAINS RELATIVE STABLE TO ACCOUNT FOR ANTICIPATED BRIEF PERIODS OF WEAKENING ASSOCIATED WITH ERC. THE POTENTIAL OF A PEAK INTENSITY GREATER THAN 130 KTS IS ALSO WITHIN THE REALM OF POSSIBILITY, DEPENDING ON HOW QUICKLY 29W IS ABLE TO CONSOLIDATE BETWEEN TAU 0-12, THEREBY IMPACTING WHEN THE SYSTEM IS ABLE TO COMMENCE RAPIDLY INTENSIFYING. ADDITIONALLY, A PEAK HIGHER THAN 130 KTS IS POSSIBLE IF THE SYSTEM IS ABLE TO SUSTAIN A RAPID RATE OF INTENSIFICATION PASSED TAU 60. MODEL DISCUSSION: DETERMINISTIC MODEL TRACK GUIDANCE IS IN STRONG AGREEMENT THROUGHOUT THE FORECAST PERIOD, BUT PARTICULARLY THROUGH THE FIRST 48 HOURS. THE CROSS-TRACK SPREAD AS THE STORM PASSES THROUGH THE NORTHERN MARIANAS IS 65 NM, AND THE MODEL ENVELOP BOASTS NO OUTLIERS. AT TAU 120, THE MODEL GUIDANCE REMAINS IN STRONG AGREEMENT, MAINTAINING A 200 NM CROSS-TRACK SPREAD. IN RESPONSE TO THE MOMENTARY WESTWARD JAUNT WITHIN THE LAST 6 HOURS, INTERPOLATED MODEL GUIDANCE HAS SHIFTED SLIGHTLY SOUTHWARD, HOWEVER, THE JTWC TRACK FORECAST REMAINS CONSISTENT AND IN CLOSE ALIGNMENT WITH GFS, GEFS, ECENS, AND GSM WITH OVERALL HIGH CONFIDENCE. RELIABLE INTENSITY AIDS ARE IN GOOD AGREEMENT THROUGH TAU 24, THOUGH THERE IS SOME DISAGREEMENT REGARDING THE TIMING OF RI. SEVERAL JTWC RI INDICATORS HAVE REACHED TRIP CRITERIA, SUPPORTING THE POSSIBILITY OF RI OCCURRING WITHIN THE NEXT 12-24 HOURS. HOWEVER, THE HWRF SOLUTION DEPICT RI BEGINNING AS LATE AS TAU 48, AND GFS AND COAMPS-TC DEPICTING NO RI AT ALL. THE LIKELIHOOD OF NO RI IS EXTREMELY UNLIKELY GIVEN THE ENVIRONMENT, SO THOSE SOLUTIONS WERE DISCOUNTED IN THE INTENSITY FORECAST. MODEL GUIDANCE ALSO DISAGREES ON THE PEAK INTENSITY AND THE TIMING OF THE PEAK. THE PEAK INTENSITY SPREAD RANGES FROM 105 KTS AND 135 KTS, WITH THE TIMING SPREAD BETWEEN TAU 72 AND TAU 96. THE JTWC INTENSITY FORECAST IS IN CLOSE AGREEMENT WITH THE RI AIDS AND THE BULK OF MODELS FROM TAU 0-24, THEN HEDGED CLOSER TO THE RI AIDS AND GOOGLE DEEPMIND SOLUTIONS FROM TAU 24-120 WITH HWRF AND COAMPS-TC ALSO IN GOOD AGREEMENT BY TAU 96. THE JTWC INTENSITY FORECAST IS ASSESSED WITH OVERALL MEDIUM CONFIDENCE. FORECAST CONFIDENCE: TRACK 00-72 HR: HIGH TRACK 72-120 HR: HIGH INTENSITY 00-72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN