Advisories

WDPN31 PGTW 060900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 12W (DOLPHIN) WARNING NR 042//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 26.6N 132.6E
   INITIAL INTENSITY: 80 KTS
   GEOGRAPHIC REFERENCE: 258 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 MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TYPHOON (TY)
12W (DOLPHIN) AS AN EXPANSIVE SYSTEM, WITH A CLOUD SHIELD
APPROXIMATELY 550 NM IN DIAMETER AND LOW-LEVEL INFLOW EXTENDING FAR
BEYOND THAT. 12W ALSO SPORTS A CLOUD-FILLED PINHOLE EYE MEASURING
APPROXIMATELY 10 NM IN DIAMETER SITUATED ASYMMETRICALLY INSIDE A
TIGHTLY WOUND INNER CORE. A DRY SPIRAL EXTENDS FROM THE SOUTHERN
PERIPHERY AND WRAPS INWARD, INDICATED IN ANIMATED INFRARED IMAGERY BY 
A DISTINCT LACK OF COLD CLOUD TOPS. THE 060646Z SSMIS IMAGE
CONFIRMS THIS OBSERVATION BY REVEALING AN INNER CORE OF DEEP
CONVECTION SURROUNDED BY A LARGE DRY MOAT THAT SEPARATES THE SECOND 
RING OF DEEP CONVECTION. ENVIRONMENTAL ANALYSIS INDICATES A FAVORABLE
ENVIRONMENT, CHARACTERIZED BY LOW (10-15 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 PINHOLE EYE. THE INITIAL INTENSITY OF 80
KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE AGENCY DVORAK
FIXES AND AUTOMATED CIMSS INTENSITY ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: ADJUSTED THE NORTHERN 34 KT WIND RADII
USING THE 060005Z AND 060144Z ASCAT PASSES.

CURRENT STEERING MECHANISM: SOUTHERN FLANK OF A DEEP-LAYER
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: T4.0 - 65 KTS
   KNES: T5.0 - 90 KTS
   CIMSS SATCON: 84 KTS AT 060630Z
   CIMSS ADT: 82 KTS AT 060630Z
   CIMSS AIDT: 85 KTS AT 060630Z
   CIMSS D-MINT: 80 KTS AT 060646Z
   CIMSS D-PRINT: 75 KTS AT 060630Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE 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: TY 12W IS FORECAST TO CONTINUE TRACKING
GENERALLY 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 24-72. 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 BETWEEN TAU 72-96. REGARDING
INTENSITY, 12W IS FORECAST TO GENERALLY MAINTAIN INTENSITY THROUGH
TAU 72. THE SYSTEM MAY MOMENTARILY SLIGHTLY INTENSIFY IN THE NEXT
12-24 HOURS AS IT TRACKS OVER A REGION OF SLIGHTLY ELEVATED OCEAN
HEAT CONTENT ASSOCIATED WITH THE KUROSHIO CURRENT; HOWEVER, THE
LARGE AND COMPLEX STRUCTURE OF THE STORM WILL PREVENT SIGNIFICANT
INTENSIFICATION. DOLPHIN IS FORECAST TO WEAKEN SLIGHTLY LEADING UP
TO LANDFALL IN CHINA, AS THE OCEAN HEAT CONTENT DROPS AND THE TRACK
SPEED SLOWS, INTRODUCING COMPOUNDING EFFECTS FROM THE STORM'S COLD
WAKE. AFTER LANDFALL, 12W IS EXPECTED TO DRASTICALLY WEAKEN OVER
LAND AND FULLY DISSIPATE AFTER TAU 120.

MODEL DISCUSSION: DETERMINISTIC MODEL TRACK GUIDANCE IS IN STRONG
AGREEMENT THROUGH TAU 72, 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. AFTER TAU 72, 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,
TERRAIN INTERACTION WILL INTRODUCE ADDITIONAL UNCERTAINTY, AS THE
STORM MAY BEHAVE ERRATICALLY AND UNPREDICTABLY OVER LAND. 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 STRENGTH, WITH MINOR FLUCTUATIONS IN
INTENSITY. THE JTWC INTENSITY FORECAST IS PLACED IN LINE WITH THE
HAFS-A SOLUTION. AS A RESULT, THE JTWC TRACK FORECAST IS ASSESSED
WITH OVERALL MEDIUM CONFIDENCE, WITH UNCERTAINTY STEMMING FROM THE
POTENTIAL FOR A BRIEF REINTENSIFICATION IN THE NEAR-TERM FORECAST
AND THE WEAKENING TREND POST-LANDFALL IN THE LATE-TERM FORECAST.

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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