Advisories

WDPN31 PGTW 062100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 12W (DOLPHIN) WARNING NR 044//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 26.9N 130.4E
   INITIAL INTENSITY: 80 KTS
   GEOGRAPHIC REFERENCE: 141 NM EAST OF KADENA AB
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 40 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS
DISCONTINUOUS DEEP CONVECTIVE BANDING SURROUNDING A COMPACT INNER
CORE WITH A SMALL 10 NM RAGGED EYE. THE DEEP CONVECTION SURROUNDING
THE INNER CORE THAT MAKES UP THE EYEWALL HAD BEEN ERODING ON THE
WESTERN SIDE EARLIER BUT NOW APPEARS TO BE RECONSTITUTING WITHIN
THE PAST FEW HOURS. A 061725Z AMSR-2 37 GHZ MICROWAVE IMAGE
HIGHLIGHTS THE DISCONTINUOUS STRUCTURE OF THE CONVECTIVE BANDING
AND THE WEAKNESS OF CONVECTION IN THE WESTERN SIDE OF THE CORE
CONVECTION. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE
BASED ON THE RAGGED EYE IN IR IMAGERY AND EXTRAPOLATION FROM THE
MICROWAVE EYE IN THE AMSR-2 IMAGE. A 051300Z ASCAT-C WIND SPEED
PRODUCT REVEALED THE NEARLY 500 NM DIAMETER EXTENT OF GALE FORCE
WINDS SURROUNDING THE SYSTEM. NOTABLY, THE ASCAT-C IMAGE SHOWS THAT
THE WIND FIELD IN THE SOUTHERN SEMICIRCLE HAS BECOME MORE
HOMOGENEOUS AND LESS INTENSE THAN WHAT HAS BEEN OBSERVED OVER THE
PAST FEW DAYS. THE INITIAL INTENSITY OF 80 KTS IS ASSESSED WITH
MEDIUM CONFIDENCE BASED ON UNANIMOUS T4.5 DVORAK CURRENT
INTENSITIES FROM THE FIXING AGENCIES, HEDGED SLIGHTLY HIGHER GIVEN
THE LITTLE CHANGE IN OVERALL SATELLITE PRESENTATION. THE
ENVIRONMENT IS CHARACTERIZED AS FAVORABLE, WITH WARM SEA SURFACE
TEMPERATURES, LOW VERTICAL WIND SHEAR (VWS), AND EXCELLENT RADIAL
OUTFLOW.

INITIAL WIND RADII BASIS: PERSISTENCE

CURRENT STEERING MECHANISM: SOUTHWESTERN FLANK OF A SUBTROPICAL
RIDGE CENTERED OVER HONSHU

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   RJTD: T4.5 - 77 KTS
   RCTP: T4.5 - 77 KTS
   KNES: T4.5 - 77 KTS
   CIMSS SATCON: 73 KTS AT 061800Z
   CIMSS ADT: 61 KTS AT 061800Z
   CIMSS AIDT: 72 KTS AT 061800Z
   CIMSS D-MINT: 75 KTS AT 061749Z
   CIMSS D-PRINT: 74 KTS AT 061730Z

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 6 HOURS UNDER THE
STEERING INFLUENCE OF THE STR OVER HONSHU. THE SYSTEM IS FORECAST
TO CONTINUE NEARLY DUE WESTWARD THROUGH TAU 60 AS THE STEERING
RIDGE MIGRATES EAST AND A WEAKER RIDGE EXTENSION BUILDS IN FROM THE
WEST. THE TRACK SPEED IS EXPECTED TO SLOW SLIGHTLY BETWEEN TAU
36-60 AS THE STEERING GRADIENT WEAKENS BETWEEN THE TWO RIDGE
FEATURES. AFTER TAU 60, THE STEERING ENVIRONMENT GETS A BIT MORE
COMPLICATED WITH THE PASSAGE OF A MIDLATITUDE TROUGH TO THE NORTH,
INTRODUCING SOME UNCERTAINTY IN THE RECURVING TRACK. THE CPA TO
KADENA AB AROUND 080900Z IS 42 NM, HOWEVER, THE EXPANSIVE WIND
FIELD HAS ALREADY REACHED OKINAWA, WITH 40+ KT GUSTS OBSERVED AT
RODN SINCE 1600Z. TY 12W IS EXPECTED TO MAKE LANDFALL IN EASTERN
CHINA AROUND TAU 72 AS IT BEGINS TO RECURVE NORTHWESTWARD. THE
INTENSITY IS FORECAST TO REMAIN STEADY AROUND 80 KTS UNTIL TAU 48,
AFTER WHICH A STEADY WEAKENING TREND WILL BE INITIATED BY LOWER
OCEAN HEAT CONTENT AND PROXIMITY TO MAINLAND CHINA. RAPID
DISSIPATION IS EXPECTED AS THE SYSTEM RECURVES INLAND OVER EASTERN
CHINA.  

MODEL DISCUSSION: MODEL TRACK GUIDANCE IS IN GOOD AGREEMENT ABOUT
THE WESTWARD TRAJECTORY THROUGH TAU 60, THEN SPREADS THROUGH THE
LATER TAUS AS A RESULT OF THE UNCERTAINTY IN THE STEERING
ENVIRONMENT AND LAND INTERACTION. THE CROSS-TRACK SPREAD AT TAU 72
IS 100 NM, WHEN LANDFALL IS EXPECTED, AND REMAINS LARGE OVER
EASTERN CHINA. THE JTWC TRACK FORECAST IS PLACED NEAR THE
MULTI-MODEL CONSENSUS WITH A SLIGHT BIAS TOWARD THE AI MODEL
CONSENSUS THAT HAS STATISTICALLY PERFORMED WELL FOR 12W. THE
INTENSITY GUIDANCE FALLS WITHIN A 15KT ENVELOPE (WITH THE EXCEPTION
OF CTCI, WHICH PREDICTS AN INTENSIFICATION PHASE) AND IN GOOD
AGREEMENT ABOUT THE OVERALL STEADY THEN WEAKENING TREND. THUS, THE
JTWC INTENSITY FORECAST IS PLACED NEAR THE CONSENSUS THROUGHOUT THE
FORECAST PERIOD.

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