Advisories

WDPN31 PGTW 052100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 12W (DOLPHIN) WARNING NR 040//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 26.3N 135.0E
   INITIAL INTENSITY: 80 KTS
   GEOGRAPHIC REFERENCE: 388 NM EAST OF KADENA AB
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 40 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS THE
SMALL EYE FEATURE OF TYPHOON 12W PERSISTING OVER THE PAST SIX
HOURS, ALTHOUGH RAGGED AND OCCASIONALLY BECOMING OBSCURED. THE CORE
OF CONVECTION SURROUNDING THE EYEWALL PERSISTS AS WELL AND IS
BEGINNING TO SHOW SIGNS OF EXPANSION AND SYMMETRIZATION IN ALL BUT
THE SOUTHEAST QUADRANT.  THE STATIONARY BANDING CONVECTIVE FEATURE
(SBC) HAS STRUGGLED TO REMAIN CONTINUOUS OR WRAP COMPLETELY AROUND
THE COMPACT CORE, LEAVING A PROMINENT MOAT OF DRIER AIR BETWEEN THE
COMPACT CORE AND THE SBC. THE MOAT IS ALSO APPARENT IN A 051643Z
AMSR-2 36 GHZ MICROWAVE IMAGE WHICH HINTS AT THE POTENTIAL FOR AN
ADDITIONAL EYEWALL REPLACEMENT CYCLE IN THE FUTURE, THOUGH PROBABLY
NOT IMMINENTLY AS IT HAS BEEN SLOW TO SET UP. EARLIER 050850Z RCM-3
AND 050855Z SENTINEL-1 SAR IMAGES REVEALED A PERSISTENT SWATH OF
LOWER WIND SPEED IN THE SOUTHERN SEMICIRCLE SEPARATING THE HIGHEST
WINDS WITHIN THE COMPACT CORE AND THE BROAD WIND FIELD SURROUNDING
THE SYSTEM AS A WHOLE. THIS FEATURE HAS BEEN PRESENT IN SAR IMAGES
OVER THE PAST 48 HOURS. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON THE SMALL EYE FEATURE IN IR IMAGERY. THE
INITIAL INTENSITY OF 80 KTS IS ASSESSED WITH MEDIUM CONFIDENCE
BASED ON THE SPREAD OF AGENCY DVORAK FIXES AND CIMSS OBJECTIVE
INTENSITY ESTIMATES. THE ENVIRONMENT IS CHARACTERIZED AS FAVORABLE
WITH SELF-SUSTAINING RADIAL OUTFLOW ALOFT, WARM SEA SURFACE
TEMPERATURES, AND LOW VERTICAL WIND SHEAR (VWS).

INITIAL WIND RADII BASIS: PERSISTENCE FROM SAR WIND SPEED DATA

CURRENT STEERING MECHANISM: SOUTHERN FLANK OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) CENTERED OVER THE SEA OF JAPAN (SOJ)

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   RJTD: T5.5 - 102 KTS
   RCTP: T4.0 - 65 KTS
   KNES: T4.5 - 77 KTS
   CIMSS SATCON: 87 KTS AT 051630Z
   CIMSS ADT: 77 KTS AT 051800Z
   CIMSS AIDT: 80 KTS AT 051800Z
   CIMSS D-MINT: 78 KTS AT 051722Z
   CIMSS D-PRINT: 78 KTS AT 051800Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG RADIAL

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: TYPHOON (TY) 12W (DOLPHIN) HAS CONTINUED ON A
WOBBLING WEST-NORTHWESTWARD TRACK OVER THE PAST SIX HOURS UNDER THE
STEERING INFLUENCE OF THE STR OVER THE SEA OF JAPAN. THE
DEVELOPMENT OF THE STEERING SCENARIO HAS SHIFTED IN FAVOR OF THE
STR PERSISTING AND DRIVING A WEST-NORTHWESTWARD TRACK THROUGH TAU
72, THEN TURNING NORTHWESTWARD AS THE SYSTEM MAKES LANDFALL SOUTH
OF SHANGHAI AROUND TAU 96 AND BEYOND. THE CPA TO KADENA HAS SHIFTED
SLIGHTLY FARTHER NORTH UNDER THIS STEERING REGIME, NOW EXPECTED
AROUND 070800Z. TY 12W HAS WEAKENED A BIT MORE THAN EXPECTED OVER
THE PAST 12 HOURS BUT GENERALLY FAVORABLE ENVIRONMENTAL CONDITIONS
ARE EXPECTED TO ALLOW THE SYSTEM TO MAINTAIN AN INTENSITY OF 80 KTS
AS IT APPROACHES OKINAWA. DYNAMIC FACTORS RELATING TO THE SYSTEM
STRUCTURE (EYEWALL REPLACEMENT AND BROADENING WIND FIELD) COULD
RESULT IN SOME FLUCTUATIONS ABOVE OR BELOW 80 KTS. AFTER TAU 48, A
GRADUAL WEAKENING TREND IS FORECAST UNTIL THE SYSTEM MAKES
LANDFALL. AFTER LANDFALL, THE SYSTEM WILL RAPIDLY DECAY OVER
EASTERN CHINA. 

MODEL DISCUSSION: MODEL TRACK GUIDANCE IS NOW IN BETTER AGREEMENT
ABOUT THE WEST-NORTHWESTWARD TRACK UP UNTIL LANDFALL AROUND TAU
96. THE PREVIOUS TREND OF GLOBAL MODELS DEPICTING A SHARPER RECURVE
IN THE EAST CHINA SEA IS NO LONGER EVIDENT. THE CROSS-TRACK SPREAD
AT TAU 96 IS STILL QUITE SIGNIFICANT AT 280 NM AS A RESULT OF
UNCERTAINTY IN THE EVENTUAL RECURVING SCENARIO. THE JTWC TRACK
FORECAST IS PLACED CLOSE TO A MODIFIED MULTI-MODEL CONSENSUS THAT
REMOVES GALWEM AS A SOUTHERN OUTLIER, NAVGEM AS A SHARPLY RECURVING
OUTLIER, AND GFS AS THE NORTHERN OUTLIER. WITH THE EXCEPTION OF GFS
AND COAMPS-TC SOLUTIONS, WHICH DEPICT A PROMINENT PERIOD OF
INTENSIFICATION, THE MODEL INTENSITY GUIDANCE IS IN GOOD AGREEMENT
ABOUT THE PERSISTENCE OF INTENSITY FOLLOWED BY GRADUAL WEAKENING
BEFORE LANDFALL AND RAPID DISSIPATION. THE JTWC INTENSITY FORECAST
IS PLACED AMONG THE LATTER GROUPING WITH MEDIUM CONFIDENCE
THROUGHOUT THE FORECAST PERIOD. 

FORECAST CONFIDENCE:
   TRACK 00-72 HR: HIGH
   TRACK 72-120 HR: MEDIUM
   INTENSITY 00-72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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