Advisories

WDPN31 PGTW 080900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 12W (DOLPHIN) WARNING NR 050//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 26.9N 125.2E
   INITIAL INTENSITY: 75 KTS
   GEOGRAPHIC REFERENCE: 141 NM WEST OF KADENA AB
   MOVEMENT PAST 6 HOURS: WESTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 30 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS AN EXPANSIVE
CYCLONIC CIRCULATION ENCOMPASSING THE MAJORITY OF THE EAST CHINA
SEA (ECS). WITHIN THE BROAD EXPANSE OF THE OUTER RAIN BANDS SITS AN
EXTREMELY SMALL INNER CORE OF DEEP CONVECTION, WITH A CLOUD-FILLED
EYE FEATURE THAT IS CLEARLY EVIDENT IN BOTH RADAR AND MICROWAVE
IMAGERY. A 080507Z AMSR2 89GHZ IMAGE REVEALS A 5NM WIDE EYE
SURROUNDED BY MODERATE TO DEEP CONVECTION, AND MULTIPLE MOATS
BETWEEN THE RAIN BANDS, THE OUTERMOST OF WHICH EXTEND FROM SASEBO AND
AMAMI OSHIMA IN THE EAST TO THE NORTHERN TIP OF TAIWAN AND THE
SOUTHWESTERN ISLANDS OF THE RYUKYUS IN THE SOUTH. THE INITIAL
POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE RADAR AND
MICROWAVE DATA. THE INITIAL INTENSITY IS ASSESSED WITH MEDIUM
CONFIDENCE. OBJECTIVE INTENSITY ESTIMATES DIFFER SIGNIFICANTLY DUE
TO THE HYBRID/COMPLEX STRUCTURE OF THE SYSTEM. REGIONAL SURFACE
OBSERVATIONS SUPPORT THE INITIAL WIND RADII ANALYSIS WITH HIGH
CONFIDENCE. ENVIRONMENTAL CONDITIONS REMAIN FAVORABLE WITH LOW
DEEP-LAYER VWS, WARM SSTS AND GOOD RADIAL OUTFLOW ALOFT.

INITIAL WIND RADII BASIS: PERSISTENCE AND OBJECTIVE BEST TRACK. 

CURRENT STEERING MECHANISM: WEAK STEERING PATTERN, DOMINATED BY A
MESOSCALE DEEP-LAYER SUBTROPICAL RIDGE (STR) OVER SOUTHERN JAPAN. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   RJTD: T5.0 - 90 KTS
   RCTP: T4.5 - 77 KTS
   KNES: T5.0 - 90 KTS
   CIMSS SATCON: 84 KTS AT 080400Z
   CIMSS ADT: 55 KTS AT 080600Z
   CIMSS AIDT: 67 KTS AT 080600Z
   CIMSS D-MINT: 73 KTS AT 080507Z
   CIMSS D-PRINT: 70 KTS AT 080600Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 0-5 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG RADIAL
   OTHER FACTORS: CYCLONIC OUTFLOW ALOFT OVER THE CENTER; EXPANSIVE
SIDE OF THE OUTER PERIPHERY OF THE CIRCULATION.

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: HIGH

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TYPHOON (TY) 12W CONTINUES ITS SLOW, TROCHOIDAL 
MOTION, GENERALLY HEADING WESTWARD DEEPER INTO THE ECS. OVER THE PAST 
12 HOURS, THE SYSTEM COMPLETED ANOTHER CYCLONIC LOOP AND HAS 
DECELERATED, EXHIBITING CONTINUED MEANDERING PRIOR TO ESTABLISHING A 
SUSTAINED WESTWARD TRACK. THE ERRATIC MOTION WITNESSED OVER THE PAST 
TWO DAYS IS ATTRIBUTABLE TO A WEAK STEERING ENVIRONMENT PRODUCED BY A 
BREAK IN THE STR OVER KOREA, COMBINED WITH THE DYNAMICS WHERE THE 
INNER CORE IS COCOONED WITHIN A MUCH LARGER PARENT CIRCULATION. WHILE 
THE GENERAL STEERING PATTERN IS WEAK, A MESOSCALE DEEP-LAYER RIDGE IS 
SEEN BUILDING OVER SOUTHERN JAPAN. THIS RIDGE IS EXPECTED TO CONTINUE 
TO BUILD AND EXPAND WESTWARD, WHICH WILL DRIVE TY 12W WESTWARD THROUGH 
LANDFALL, EXPECTED ALONG THE SOUTHEASTERN COAST OF ZHEJIANG PROVINCE, 
CHINA, BETWEEN TAU 24 AND TAU 36. AFTER MAKING LANDFALL, THE SYSTEM 
WILL MOVE INLAND, CURVE AROUND THE WESTERN SIDE OF THE RIDGE AND TURN 
NORTHWESTWARD THROUGH THE REMAINDER OF THE FORECAST PERIOD. THE 
ENVIRONMENT REMAINS FAVORABLE FOR INTENSIFICATION, THOUGH DRY AIR 
ENTRAINMENT MAY DISRUPT THE INNER CORE. HOWEVER, TY 12W HAS DISPLAYED 
STRUCTURAL RESILIENCE, AND HIGH-RESOLUTION MODEL GUIDANCE (HWRF IN 
PARTICULAR) CONTINUES TO DEPICT A SLIGHT AMOUNT OF INTENSIFICATION 
JUST PRIOR TO LANDFALL. SSTS ARE PARTICULARLY WARM ALONG THE EASTERN 
COAST OF CHINA, THOUGH OHC IS LOW. WEIGHING ALL FACTORS, THE SYSTEM IS 
FORECAST TO MAINTAIN INTENSITY THROUGH TAU 12, BEFORE WEAKENING 
SLIGHTLY PRIOR TO MAKING LANDFALL AS A LOW-END TYPHOON. THERE REMAINS 
A LOW PROBABILITY SCENARIO THAT WOULD HAVE THE SYSTEM INTENSIFY PRIOR 
TO LANDFALL. ONCE THE SYSTEM IS ASHORE, IT WILL QUICKLY WEAKEN AND 
DISSIPATE FAR WEST OF SHANGHAI BY TAU 72. 

MODEL DISCUSSION: TRACK GUIDANCE, INCLUDING DETERMINISTIC, ENSEMBLE
AND EXPERIMENTAL AI-BASED MODEL TRACKERS, ARE IN GOOD AGREEMENT
THROUGH THE ENTIRE FORECAST PERIOD. THE JTWC FORECAST IS PLACED
NEAR THE MULTI-MODEL CONSENSUS MEAN WITH HIGH CONFIDENCE. INTENSITY
GUIDANCE IS ALSO IN GOOD AGREEMENT WITH ONE NOTABLE OUTLIER, THAT
BEING THE HWRF, WHICH DEPICTS THE SYSTEM INTENSIFYING TO 90 KNOTS
BY TAU 24. THE REMAINDER OF THE GUIDANCE PACKAGE SHOWS A STEADY
INTENSITY THROUGH LANDFALL FOLLOWED BY A STEADY WEAKENING THROUGH
DISSIPATION. THE JTWC FORECAST IS POSITIONED ON THE HIGHER END OF
THE GUIDANCE ENVELOPE WITH MEDIUM CONFIDENCE. AS DISCUSSED ABOVE,
THE HWRF SOLUTION CANNOT BE FULLY DISCOUNTED, WHICH LENDS DECREASED
CONFIDENCE TO THE JTWC INTENSITY FORECAST.  

FORECAST CONFIDENCE:
   TRACK 00-72 HR: HIGH
   INTENSITY 00-72 HR: MEDIUM//
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