Advisories

WDPN31 PGTW 061500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 12W (DOLPHIN) WARNING NR 043//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 26.5N 131.5E
   INITIAL INTENSITY: 80 KTS
   GEOGRAPHIC REFERENCE: 199 NM EAST OF KADENA AB
   MOVEMENT PAST 6 HOURS: WESTWARD AT 10 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 SPARSE PATCHES OF DEEP CONVECTION PEPPERED
THROUGHOUT THE UPPER LEVEL CLOUD SHIELD, WITH NO REAL STRUCTURE OR
CONSISTENCY. THE DRY MOAT STRETCHING INTO THE CORE FROM THE
SOUTHERN PERIPHERY IS EXPANDING AND REDUCING DEEP CONVECTION
THROUGHOUT THE STORM. ADDITIONALLY, THE NORTHWESTERN QUADRANT OF
THE EYEWALL IS SHALLOWING AND THE EYE ITSELF IS NEARLY COMPLETELY
FILLED. A SURFACE OBSERVATION FROM AMAMI OSHIMA IS REPORTING 44 KTS
SUSTAINED AND 56 KT GUSTS, SUPPORTING BOTH THE INITIAL INTENSITY
AND THE NORTHWESTERN QUADRANT 34 KT WIND RADII. THE ENVIRONMENT IS
FAVORABLE, CHARACTERIZED BY LOW (5-10 KTS) VERTICAL WIND SHEAR
(VWS), WARM (29-30 C) SEA SURFACE TEMPERATURES (SST), AND GOOD
DIVERGENCE ALOFT. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON THE CLOUD-FILLED PINHOLE EYE IN ANIMATED EIR.
THE INITIAL INTENSITY OF 80 KTS IS ASSESSED WITH MEDIUM CONFIDENCE
BASED ON THE AGENCY DVORAK FIXES AND CIMSS AUTOMATED INTENSITY
ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: THE SOUTHWESTERN PERIPHERY OF A MID- TO
UPPER-LEVEL SUBTROPICAL RIDGE (STR) CENTERED OVER THE SEA OF 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 ADT: 74 KTS AT 061200Z
   CIMSS AIDT: 78 KTS AT 061200Z
   CIMSS D-PRINT: 84 KTS AT 061100Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 0-5 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE RADIAL

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TY 12W IS FORECAST TO CONTINUE TRACKING
WESTWARD TO WEST-NORTHWESTWARD THROUGH TAU 72 WHILE IT REMAINS UNDER
THE STEERING INFLUENCE OF THE STR CENTERED OVER THE SEA OF JAPAN. A
TROUGH PASSING OVER SIBERIA WILL WEAKEN THE STR, INDUCING SLOWER
TRANSLATION SPEEDS BETWEEN TAU 24-48. AROUND TAU 72, THE STEERING
RIDGE WILL REORIENT TO THE NORTHEAST OF THE SYSTEM AND BUILD,
ACCELERATING TRACK SPEEDS AND INDUCING A NORTHWESTWARD CURVE. 12W
IS FORECAST TO MAKE LANDFALL IN CHINA JUST AFTER TAU 72. REGARDING
INTENSITY, 12W IS FORECAST TO MAINTAIN INTENSITY THROUGH TAU 12,
THEN INTENSIFY SLIGHTLY AS IT TRACKS OVER A WARM POOL OF SLIGHTLY
HIGHER OCEAN HEAT CONTENT ASSOCIATED WITH THE KUROSHIO CURRENT.
THIS PERIOD OF SLIGHTLY HIGHER INTENSITIES WILL LAST APPROXIMATELY
48 HOURS, FROM TAU 24-60. AFTER, 12W IS FORECAST TO WEAKEN BETWEEN
TAU 60-72 AS IT EXITS THE WARM POOL AND APPROACHES LAND. ONCE
DOLPHIN MAKES LANDFALL, IT IS EXPECTED TO DRAMATICALLY WEAKEN AND
FULLY DISSIPATE BY TAU 120.

MODEL DISCUSSION: DETERMINISTIC MODEL TRACK GUIDANCE IS IN STRONG
AGREEMENT THROUGH TAU 60, WITH THE EXCEPTION OF NAVGEM, WHICH HAS
BEEN THE CONSISTENT AND SOLE EQUATORWARD OUTLIER. DISCOUNTING
NAVGEM, THE JTWC TRACK FORECAST IS PLACED WITH HIGH CONFIDENCE FROM
TAU 0-72. FOLLOWING TAU 60, THE CROSS-TRACK SPREAD DRAMATICALLY
INCREASES, AS MODELS DISAGREE ON THE ORIENTATION OF THE STEERING
RIDGE, ULTIMATELY INFLUENCING WHERE ALONG THE COAST 12W WILL MAKE
LANDFALL AND THE NORTHWESTWARD TURN THEREAFTER. ADDITIONALLY,
UNCERTAINTY IN THE LATE-TERM FORECAST ARISES AFTER 12W MAKES
LANDFALL, AND THE POSSIBILITY OF ERRATIC MOTION DUE TO TERRAIN
INTERACTION. AS A RESULT, THE JTWC TRACK FORECAST IS PLACED WITH
LOW CONFIDENCE FROM TAU 72-120. RELIABLE INTENSITY AIDS ARE IN GOOD
AGREEMENT THAT 12W WILL GENERALLY MAINTAIN INTENSITY THROUGH TAU
12-24, AND REINTENSIFY SLIGHTLY BETWEEN TAU 24-60. THE JTWC
INTENSITY FORECAST IS PLACED IN LINE WITH THE HAFS-A SOLUTION AND
THE MULTI-MODEL CONSENSUS. AS A RESULT, THE JTWC TRACK FORECAST IS
ASSESSED WITH OVERALL MEDIUM CONFIDENCE, WITH UNCERTAINTY STEMMING
FROM THE BRIEF REINTENSIFICATION IN THE NEAR-TERM FORECAST AND THE
WEAKENING TREND FOLLOWING LANDFALL. 

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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