Advisories

WDPN31 PGTW 071500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 12W (DOLPHIN) WARNING NR 047//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 27.2N 127.2E
   INITIAL INTENSITY: 90 KTS
   GEOGRAPHIC REFERENCE: 53 NM NORTHWEST OF KADENA AB
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 40 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TYPHOON
(TY) 12W (DOLPHIN) WITH A RAGGED AND FILLING EYE. A PROMINENT DRY
SLOT HAS FORMED ALONG THE WESTERN EDGE OF THE EYEWALL, ERODING IT
ALONG THE WESTERN FLANK. THE 070939Z RCM-2 SAR PASS REVEALED THE
DRY SLOT IN ANIMATED SATELLITE IMAGERY IS CORRELATED TO A REGION OF
SIGNIFICANTLY LOWER WINDSPEEDS. THE SAR DATA ALSO CONFIRMED THAT
THERE IS A BAND OF 75-85 KT WINDS DISPLACED ABOUT 80 NM NORTH OF
THE CENTER, IN ADDITION TO WINDS OF COMPARABLE STRENGTH TIGHTLY
SURROUNDING THE INNER CORE. THE ENVIRONMENT REMAINS FAVORABLE,
CHARACTERIZED BY LOW (0-5 KTS) VERTICAL WIND SHEAR (VWS), WARM
(29-30 KTS) SEA SURFACE TEMPERATURES (SST), AND GOOD OUTFLOW ALOFT.
THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE
PINHOLE EYE PRESENT IN THE ANIMATED IMAGERY. THE INITIAL INTENSITY
OF 90 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE EARLIER
070939Z SAR PASS, AND THE AGENCY DVORAK FIXES AND CIMSS INTENSITY
ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: ADJUSTED 50 KT AND 64 KT WIND RADII USING
THE 070939Z RCM-2 SAR DATA

CURRENT STEERING MECHANISM: SOUTHWESTERN FLANK OF A SUBTROPICAL
RIDGE CENTERED OVER THE SEA OF JAPAN

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.5 - 102 KTS
   RJTD: T5.5 - 102 KTS
   RCTP: T5.0 - 90 KTS
   KNES: T5.5 - 102 KTS
   CIMSS ADT: 94 KTS AT 071300Z
   CIMSS AIDT: 92 KTS AT 071300Z
   CIMSS D-PRINT: 92 KTS AT 071230Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 0-5 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE RADIAL
   OTHER FACTORS: SIGNIFICANT DRY AIR ENTRAINMENT

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: TY 12W (DOLPHIN) IS FORECAST TO CONTINUE
TRACKING GENERALLY WESTWARD TO NORTH-NORTHWARD WHILE IT REMAINS
UNDER THE INFLUENCE OF THE STR CENTERED OVER THE SEA OF JAPAN. THE
TROUGH CURRENTLY ERODING THE STR IS EXPECTED TO PASS BY AROUND TAU
24, ALLOWING THE NOW SHALLOW STR TO REORIENT AND BUILD IN THE
MIDLEVELS TO THE NORTHEAST OF THE SYSTEM, DRIVING A GENTLE
NORTHWESTWARD CURVE BEGINNING AROUND TAU 24. LANDFALL IN CHINA IS
EXPECTED AROUND TAU 48. REGARDING INTENSITY, 12W HAS MAINTAINED
INTENSITY WHILE IT REMAINS OVER THE WARM POOL OF RELATIVELY HIGHER
OCEAN HEAT CONTENT (OHC) ASSOCIATED WITH THE KUROSHIO CURRENT.
DOLPHIN IS EXPECTED TO MAINTAIN THIS INTENSITY APPROXIMATELY FOR
THE NEXT 12 HOURS AND EXIT THE WARMER OHC VALUES AROUND TAU 24. THE
LOWERING OHC VALUES WILL CONTRIBUTE TO SLIGHT WEAKENING LEADING UP
TO LANDFALL. DOLPHIN IS FORECAST TO RAPIDLY WEAKEN OVER LAND AND
FULLY DISSIPATE BY TAU 96.

MODEL DISCUSSION:  DETERMINISTIC MODEL TRACK GUIDANCE IS IN STRONG
AGREEMENT THROUGH LANDFALL AT TAU 48, LENDING HIGH CONFIDENCE TO
THE SHORT-TERM TRACK FORECAST. MODELS DIVERGE SIGNIFICANTLY
POST-LANDFALL, CONTRIBUTING TO UNCERTAINTY SURROUNDING THE TRACK
FORECAST FROM TAU 72-96. AS A RESULT, THE JTWC TRACK FORECAST IS
PLACED WITH HIGH CONFIDENCE FROM TAU 0-72 AND LOW CONFIDENCE FROM
TAU 72-96. RELIABLE INTENSITY AIDS ARE IN STRONG AGREEMENT FOR THE
DURATION OF THE FORECAST PERIOD, SUPPORTING THE JTWC INTENSITY
FORECAST WITH HIGH CONFIDENCE.

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