Advisories

WDPN31 PGTW 070300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 12W (DOLPHIN) WARNING NR 045//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 27.2N 128.8E
   INITIAL INTENSITY: 85 KTS
   GEOGRAPHIC REFERENCE: 68 NM NORTHEAST OF KADENA AB
   MOVEMENT PAST 6 HOURS: WESTWARD AT 15 KTS
   SIGNIFICANT WAVE HEIGHT: 36 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TYPHOON (TY) 12W IS INTENSIFYING. ANIMATED INFRARED IMAGERY,
ENHANCED WITH THE BD CURVE, SHOWS A SOLID RING OF VERY COLD CLOUD
TOPS, INDICATED BY BLACK AND WHITE SHADES, THAT HAS COMPLETELY
WRAPPED AROUND THE 10 NM WIDE, PINHOLE EYE. ANIMATED MULTISPECTRAL
SATELLITE IMAGERY (MSI) DEPICTS DEEP CONVECTION SPIRALING AROUND
THE EYEWALL SURROUNDED BY AN EXTENSIVE CURVED BAND WITH GOOD RADIAL
OUTFLOW ALOFT. SUCCESSIVE PASSES BY HIGH-RESOLUTION MICROWAVE
IMAGERS, INCLUDING AMSR2 AT 061725Z AND WSF-M MWI AT 062117Z,
CONFIRM THAT A PREVIOUS WEAKNESS ON THE WESTERN SIDE OF THE EYEWALL
HAS CLOSED OFF, SIGNALING STRUCTURAL CONSOLIDATION. THE ENVIRONMENT
IS FAVORABLE, CHARACTERIZED BY WARM SEA SURFACE TEMPERATURES (SST)
AND LOW VERTICAL WIND SHEAR (VWS). THE SYSTEM IS ALSO MOVING OVER A
POOL OF HIGHER OCEAN HEAT CONTENT (OHC) SURROUNDING OKINAWA,
FUELING THE INTENSIFICATION. THE INITIAL POSITION IS ASSESSED WITH
HIGH CONFIDENCE BASED ON THE SMALL, WELL-DEFINED EYE. IN LIGHT OF
THE IMPROVING CONVECTIVE STRUCTURE, THE INITIAL INTENSITY HAS BEEN
RAISED TO 85 KTS WITH MEDIUM CONFIDENCE BASED ON THE RISING
SUBJECTIVE DVORAK ESTIMATES RANGING FROM T4.5 TO T5.0, WITH A
NOTABLE DT OF 5.5 FROM PGTW AND KNES. THIS ALIGNS WITH THE HIGH END
OF THE OBJECTIVE INTENSITY ESTIMATES FROM CIMSS RANGING FROM 66 KTS
TO 89 KTS.

INITIAL WIND RADII BASIS: PERSISTENCE 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.0 - 90 KTS
   RJTD: T4.5 - 77 KTS
   RCTP: T4.5 - 77 KTS
   KNES: T5.0 - 90 KTS
   CIMSS SATCON: 80 KTS AT 062200Z
   CIMSS ADT: 72 KTS AT 060000Z
   CIMSS AIDT: 71 KTS AT 060000Z
   CIMSS D-MINT: 86 KTS AT 062132Z
   CIMSS D-PRINT: 68 KTS AT 062330Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 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 CONTINUES ON A WEST-NORTHWESTWARD
TRAJECTORY ALONG THE SOUTHERN PERIPHERY OF A WEAK STR CENTERED OVER
THE SEA OF JAPAN. OVER THE NEXT 48 HOURS, A RIDGE WILL BUILD OVER
HONSHU, WHICH WILL CONTINUE TO DRIVE THE SYSTEM WESTWARD. AS THE
SYSTEM APPROACHES THE COAST OF CENTRAL CHINA, THE SYSTEM WILL
GRADUALLY TURN POLEWARD INTO A WEAKNESS IN THE STR, CREATED BY A
TROUGH PASSING OVER MONGOLIA. TY 12W IS TRAVERSING WARM SST IN A
LOW-SHEAR ENVIRONMENT. THE STORM HAS APPROXIMATELY 24-36 HOURS
REMAINING OVER A POOL OF HIGHER OHC. GIVEN THAT THE INNER CORE IS
CONSOLIDATING, THE FORECAST CALLS FOR ADDITIONAL INTENSIFICATION TO
A PEAK OF 90 KTS. AFTER TAU 36, THE CIRCULATION WILL MOVE OVER AN
AREA OF LOWER OHC, WHICH WILL INDUCE A WEAKENING TREND PRIOR TO
LANDFALL. RAPID DECAY WILL OCCUR ONCE THE SYSTEM MOVES INLAND, WITH
DISSIPATION PREDICTED BY TAU 120.

MODEL DISCUSSION: MODELS HAVE COME INTO BETTER AGREEMENT REGARDING
THE POINT OF LANDFALL OVER CHINA. THE CROSS-TRACK SPREAD INCREASES
FROM 40 NM AT TAU 36 TO 150 NM AT LANDFALL. THE OVERALL GUIDANCE
SUITE HAS SHIFTED POLEWARD AFTER 60, WITH THE AI MODELS PREFERRING
AN EARLIER AND STRONGER POLEWARD TURN POST-LANDFALL. THE JTWC
FORECAST IS POSITIONED ALONG THE MEAN OF THE AI AND PHYSICS-BASED
MODELS WITH HIGH CONFIDENCE. AFTER LANDFALL, THE TRACK LEANS
TOWARDS THE AI CONSENSUS WITH LOW CONFIDENCE. THE INTENSITY
GUIDANCE DEPICTS A SMALL SPREAD, WITH THE MAJORITY OF THE RELIABLE
AIDS DEPICTING STEADY TO SLIGHT INTENSIFICATION IN THE FIRST 36
HOURS, FOLLOWED BY GRADUAL WEAKENING FROM TAU 36 TO TAU 60 AND
RAPID WEAKENING THEREAFTER. THE JTWC INTENSITY FORECAST CONCURS
WITH THIS PHILOSOPHY, SET WITH HIGH CONFIDENCE NEAR THE MIDDLE OF
THE GUIDANCE ENVELOPE THROUGH TAU 120.

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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