Advisories

WDPN31 PGTW 051500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 12W (DOLPHIN) WARNING NR 039//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 25.9N 136.2E
   INITIAL INTENSITY: 90 KTS
   GEOGRAPHIC REFERENCE: 454 NM EAST OF KADENA AB
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 41 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: 
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A VERY
COMPACT INNER CORE OF MODERATE CONVECTION SURROUNDING A SMALL, 
APPROXIMATELY 10NM WIDE EYE FEATURE, WHICH WAS SEVERELY ERODED ON
THE WESTERN FLANK. ANIMATED SHORTWAVE INFRARED AND PROXY VISIBLE
IMAGERY AND A 051114Z MHS 89GHZ MICROWAVE IMAGE DEPICT A STATIONARY 
BANDING FEATURE (SBC) WRAPPING IN FROM THE SOUTH, UP THE EASTERN FLANK 
AND INTO THE INNER CORE IN THE NORTHEASTERN QUADRANT, AS WELL AS A 
MOAT OF RELATIVELY DRIER AIR EXTENDING AROUND NEARLY THE ENTIRE EXTENT 
OF THE INNER CORE. LATER EIR IMAGERY DEPICTS THE EYEWALL REFORMING 
ALONG THE WESTERN FLANK OF THE SYSTEM, THOUGH THE EYE CONTINUES TO 
SHRINK IN SIZE. ANIMATED WATER VAPOR IMAGERY, AND DERIVED ATMOSPHERIC 
MOTION VECTORS CONTINUE TO SHOW CYCLONIC OUTFLOW ALOFT, WHICH TURNS 
ANTICYCLONIC ROUGHLY 100NM OUT FROM THE CENTER, AND NO DISTINCT 
OUTFLOW CHANNELS. THE INITIAL POSITION IS ASSESSED WITH HIGH 
CONFIDENCE BASED ON THE SMALL EYE IN THE EIR. THE INITIAL INTENSITY IS 
ASSESSED WITH MEDIUM CONFIDENCE BASED ON A BLEND OF THE AVAILABLE 
OBJECTIVE AND SUBJECTIVE INTENSITY ESTIMATES NOTED BELOW. LATE RECEIPT 
OF A TRIFECTA OF SAR PASSES FROM APPROXIMATELY 0900Z (S1C, RCM3 AND 
RSAT2) BRINGS THE INTENSITY ASSESSMENT INTO QUESTION, AS ALL THREE 
SHOWED A VMAX SIGNIFICANTLY LOWER THAN THE CURRENT INTENSITY 
ESTIMATES. THOUGH RECEIVED TOO LATE TO INFLUENCE THIS FORECAST, LATER 
REANALYSIS MAY RESULT IN A LOWER INITIAL INTENSITY. ENVIRONMENTAL 
CONDITIONS REMAIN GENERALLY FAVORABLE. SSTS REMAIN VERY WARM, THOUGH 
OHC IS LOW AS THE WARM LAYER IS VERY THIN. OHC INCREASES TO THE WEST 
REACHING A LOCAL MAXIMUM JUST EAST OF OKINAWA. UPPER-LEVEL OUTFLOW IS 
MODERATE TO STRONG, BUT THE CYCLONIC NATURE OF THE UPPER-LEVEL FLOW 
PRODUCES AN OVERALL NEGATIVE EFFECT ON TC INTENSITY. SHEAR REMAINS 
LOW, WITH NO MAJOR CHANGES EXPECTED.

INITIAL WIND RADII BASIS: SCATTEROMETER 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: T5.0 - 90 KTS
   RJTD: T5.5 - 102 KTS
   RCTP: T4.5 - 77 KTS
   KNES: T4.5 - 77 KTS
   CIMSS ADT: 95 KTS AT 051200Z
   CIMSS AIDT: 94 KTS AT 051200Z
   CIMSS D-PRINT: 88 KTS AT 051130Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG RADIAL
   OTHER FACTORS: SECONDARY EYEWALL FORMATION. 

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: TY 12W HAS TAKEN A BIT OF A MORE
WEST-NORTHWESTWARD TRACK THAN EXPECTED OVER THE PAST 12 HOURS, SOME
OF WHICH CAN BE ATTRIBUTED TO TROCHOIDAL WOBBLE, BUT ALSO DUE TO A
SLIGHT DISPLACEMENT OF THE STR FURTHER NORTH THAN ANTICIPATED. OVER
THE PAST TWO HOURS, HOWEVER, THE TRACK APPEARS TO BE STABILIZING,
MOVING DUE WESTWARD ALONG THE 26N LATITUDE LINE. THE SYSTEM IS
EXPECTED TO CONTINUE TRACKING WEST-NORTHWESTWARD ALONG THE SOUTHERN
SIDE OF THE STR OVER THE SOJ THROUGH THE ENTIRE FORECAST PERIOD.
GLOBAL MODELS STILL SHOW A MAJOR SHORTWAVE TROUGH MOVING ACROSS
NORTHEASTERN CHINA AND INTO EASTERN RUSSIA BY TAU 48, AND THEY
STILL SHOW A WEAKNESS DEVELOPING IN THE DEEP-LAYER STEERING RIDGE
OVER THE KOREAN PENINSULA. HOWEVER, THE GLOBAL MODELS ALSO DEPICT
THE TROUGH WEAKENING AND RECEDING NORTHWARD RELATIVELY QUICKLY,
REPLACED BY DEEP-LAYER RIDGING EXTENDING POLEWARD OVER SOUTHERN
JAPAN AND INTO THE KOREAN PENINSULA BY TAU 96. THUS, THE MODELS
HAVE BEGUN TO AGREE THAT THE IMPACT ON TY 12W WILL BE LIMITED TO A
SLOWDOWN IN TRACK SPEED AFTER TAU 48, WITH LITTLE IMPACT ON THE
OVERALL TRAJECTORY OF THE SYSTEM. ENSEMBLES, WHICH WILL BE
DISCUSSED IN MORE DETAIL BELOW, ARE ALSO SHOWING DECREASED
UNCERTAINTY AND MEMBER SPREAD, WITH FEWER MEMBERS DEPICTING A
POLEWARD TURN, PROVIDING INCREASED CONFIDENCE TO THE JTWC FORECAST
TRACK. LANDFALL ON OKINAWA IS FORECAST TO OCCUR BETWEEN TAU 36 AND
TAU 48, AND A SECOND LANDFALL IS EXPECTED IN CENTRAL ZHEJIANG
PROVINCE, CHINA, SHORTLY AFTER TAU 96. OF NOTE, RECENT SAR AND
SCATTEROMETER DATA REVEALS AN ASYMMETRIC WIND FIELD, WITH A MOAT OF
RELATIVELY WEAKER, GALE-FORCE, WINDS EMBEDDED WITHIN THE
SOUTHWESTERN QUADRANT OF THE CIRCULATION BETWEEN BANDS OF HIGHER
STORM-FORCE WINDS. THIS SAME SETUP HAS PERSISTED FOR THE PAST TWO
DAYS, AND LIKELY WILL PERSIST FOR THE NEXT TWO DAYS AS THE SYSTEM
APPROACHES OKINAWA. REGARDING INTENSITY, THE SYSTEM CONTINUES TO
WEAKEN AND AS NOTED ABOVE, MAY BE WEAKER THAN CURRENTLY ESTIMATED.
HOWEVER, RELIABLE INTENSITY GUIDANCE SUGGESTS THE SYSTEM WILL CONTINUE 
TO MAINTAIN AN 80-85 KNOT INTENSITY THROUGH AT LEAST TAU 48 BEFORE IT 
BEGINS TO RAPIDLY WEAKEN IN THE EAST CHINA SEA DUE TO INCREASED SHEAR, 
AND OCEANIC UPWELLING BEFORE BEGINNING TO DISSIPATE OVER SOUTHEASTERN 
CHINA AFTER LANDFALL. 

MODEL DISCUSSION: TRACK GUIDANCE IS IN GOOD AGREEMENT AND CONTINUES
THE TREND SEEN EARLIER IN THAT THE MODELS ARE COMING INTO BETTER
AGREEMENT ON THE WEST-NORTHWESTWARD TRACK SCENARIO, WITH A COUPLE
OF NOTABLE OUTLIERS. THE NAVGEM CONTINUES TO DEVIATE FROM THE
CONSENSUS ENVELOPE AND TAKE THE SYSTEM OVER SOUTHERN OKINAWA BEFORE
STOPPING AND TURNING SHARPLY POLEWARD AFTER TAU 72 WHEREAFTER IT
TRACKS PERPENDICULAR TO THE REMAINDER OF THE GUIDANCE. THE GFS AND
GEFS COMBO STILL INSIST ON A NORTHWESTWARD TRACK AFTER TAU 72, BUT
CONTINUE TO PUSH THE TRACK FURTHER WEST WITH EAST RUN, NOW SHOWING
A TAU 120 POSITION IN THE VICINITY OF SHANGHAI. THE REMAINDER OF
THE CONSENSUS PACKAGE IS CONSTRAINED TO AN ENVELOPE THAT GRADUALLY
EXPANDS TO 170NM BY TAU 120. GALWEM IS THE SOUTHERN OUTLIER, WITH
THE CONSENSUS MEAN (BEING PULLED NORTHWARD BY GFS, GEFS AND NAVGEM)
POSITIONED ON THE NORTHERN EDGE OF THE ENVELOPE. ENSEMBLE GUIDANCE
INCLUDING GEFS, EPS, ICON, AIFS, AND GDM, CONTINUE TO TREND TOWARDS
BETTER AGREEMENT ON A WESTWARD TRACK. THE ONLY MODEL SHOWING
MEMBERS TURNING NORTHWARD IS GEFS, WHICH SHOWS ROUGHLY 50 PERCENT
OF ITS MEMBERS TURNING NORTHWESTWARD TOWARDS SHANGHAI, AND THREE
MEMBERS TURNING NORTHWARD, ALL OF WHICH ARE WEST OF 127E LONGITUDE.
THE REMAINDER OF THE MODEL MEMBERS ALL POINT TO A WEST-NORTHWEST
TRACK, WITH 99 PERCENT OF THE MEMBERS TRACKING SOUTH OF SHANGHAI.
THE JTWC FORECAST IS PLACED NEAR THE AI CONSENSUS MEAN WITH HIGH
CONFIDENCE. INTENSITY GUIDANCE IS IN RELATIVELY GOOD AGREEMENT.
ONLY THE CTCX MODEL DEPICTS SIGNIFICANT INTENSIFICATION, THOUGH
HWRF DOES SHOW THE SYSTEM REINTENSIFYING AFTER TAU 12 TO A PEAK OF
95 KNOTS. THE REMAINDER OF THE CONSENSUS MEMBERS SHOW A FLAT
INTENSITY TREND THROUGH TAU 48 FOLLOWED BY RAPID WEAKENING THROUGH
THE END OF THE FORECAST. THE JTWC FORECAST IS PLACED NEAR THE
CONSENSUS MEAN WITH MEDIUM CONFIDENCE. 

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