WDPN31 PGTW 310300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 06W (JANGMI) WARNING NR 016//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 20.9N 128.1E
   INITIAL INTENSITY: 70 KTS
   GEOGRAPHIC REFERENCE: 336 NM SOUTH OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 35 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS IMPROVING
CONVECTIVE STRUCTURE SURROUNDING A VARY LARGE (70 NM DIAMETER) EYE
FEATURE WITH SEVERAL DISTINCT LOW-LEVEL MESOVORTICIES EXPOSED WITHIN 
THE BROAD CORE. WEAK DRY AIR ENTRAINMENT IS EVIDENT IN THE WESTERN 
SEMICIRCLE WHICH HAS INHIBITED MORE RAPID CONSOLIDATION OF THE 
CONVECTION OVER THE PAST 6 HOURS. THE INITIAL POSITION IS PLACED WITH 
HIGH CONFIDENCE BASED ON THE CENTER OF THE EYE FEATURE IN THE ANIMATED 
MSI AND EXTRAPOLATION FROM THE CENTER POSITION IN A 302123Z RCM-3 SAR 
PASS. THE SAME SAR IMAGE SHOWS AN EXPANSIVE FIELD OF 70 KT WINDS IN 
THE NORTHEASTERN QUADRANT AS WELL AS AN EXTENSIVE RADIUS OF WINDS 
GREATER THAN 50 KTS SURROUNDING A VERY BROAD WIND MINIMUM. THE INITIAL 
INTENSITY OF 70 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED PRIMARILY 
ON THE SAR WIND SPEEDS, BUT THERE IS A SIZEABLE SPREAD IN INTENSITY 
VALUES FROM THE AGENCY DVORAK FIXES AND CIMSS INTENSITY ESTIMATES. THE 
ENVIRONMENT IS CHARACTERIZED AS MARGINALLY FAVORABLE, WITH 28-29 C SEA 
SURFACE TEMPERATURES (SST), LOW VERTICAL WIND SHEAR, AND MODERATE 
POLEWARD AND EQUATORWARD OUTFLOW ALOFT. THE BROADNESS OF THE SYSTEM 
AND WEAK DRY AIR ENTRAINMENT FROM THE WEST ARE CREDITED FOR THE 
LIMITED DEVELOPMENT OVER THE PAST 6 HOURS.

INITIAL WIND RADII BASIS: 302123Z RCM-3 SAR DATA, SUPPLEMENTED BY THE 
OBJECTIVE BEST TRACK

CURRENT STEERING MECHANISM: SOUTHWESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) POSITIONED NEAR IWO TO.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   RJTD: T3.5 - 55 KTS
   RCTP: T4.0 - 65 KTS
   KNES: T4.5 - 77 KTS
   CIMSS ADT: 32 KTS AT 310000Z
   CIMSS AIDT: 63 KTS AT 310000Z
   CIMSS D-MINT: 65 KTS AT 302017Z
   CIMSS D-PRINT: 62 KTS AT 310000Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 5-10 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE POLEWARD AND EQUATORWARD
   OTHER FACTORS: WEAK DRY AIR ENTRAINMENT FROM THE WEST

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) 06W (JANGMI) IS FORECAST TO
CONTINUE ALONG A NORTH-NORTHWESTWARD TRACK THROUGH TAU 24 UNDER THE
STEERING INFLUENCE OF THE STR TO THE NORTHEAST. AFTER TAU 24, TY
06W WILL WORK ITS WAY AROUND THE RIDGE AXIS ON A RECURVING NORTH-
NORTHEASTWARD TRACK THROUGH TAU 48, MAKING ITS CLOSEST POINT OF 
APPROACH TO KADENA AB AROUND TAU 30 AS THE CENTER PASSES JUST WEST OF 
OKINAWA. AFTER TAU 48, THE STEERING RIDGE IS EXPECTED TO MIGRATE SOUTH 
OVER THE MARIANA ISLANDS WHILE JANGMI SIMULTANEOUSLY APPROACHES THE 
MIDLATITUDE WESTERLIES, SETTING UP A STRONG GRADIENT STEERING FLOW. 
THIS SETUP WILL RESULT IN THE SYSTEM ACCELERATING NORTHEASTWARD ON A 
TRACK THAT PARALLELS THE SOUTHERN COAST OF HONSHU, WITH A CLOSEST 
POINT OF APPROACH TO YOKOSUKA EXPECTED NEAR TAU 80. EXTRATROPICAL 
TRANSITION IS EXPECTED TO BEGIN AROUND TAU 72, WITH THE SYSTEM 
BECOMING FULLY EXTRATROPICAL BY TAU 120 AS IT EXITS EAST-
NORTHEASTWARD. MARGINALLY FAVORABLE ENVIRONMENTAL CONDITIONS WILL 
ENABLE TY JANGMI TO MAINTAIN AN INTENSITY AT OR SLIGHTLY ABOVE 70 KTS 
THROUGH TAU 36. THEN, COOLING SST AND INCREASING WESTERLY VWS WILL AID 
IN GRADUAL WEAKENING THROUGH THE REMAINDER OF THE FORECAST PERIOD.  

MODEL DISCUSSION: MODEL TRACK GUIDANCE IS IN TIGHT AGREEMENT ABOUT
THE RECURVING SCENARIO, WITH THE NOTABLE EXCEPTION OF THE GFS
DETERMINISTIC SOLUTION, WHICH IS THE SOUTHERNMOST AND SLOWEST
MEMBER OF THE MODEL SUITE. THE ALONG-TRACK SPREAD AT TAU 72 AS A
RESULT OF THE GFS OUTLIER IS 150 NM, WHILE THE REMAINDER OF GUIDANCE 
HAS A SPREAD OF ONLY 50 NM. THE CROSS-TRACK SPREAD AT THE SAME TIME IS 
VERY CLOSE AT 40 NM. THE JTWC TRACK FORECAST IS PLACED NEAR THE MULTI-
MODEL CONSENSUS (EXCLUDING GFS) WITH HIGH CONFIDENCE THROUGHOUT THE 
FORECAST PERIOD. THE MODEL INTENSITY GUIDANCE IS IN GOOD AGREEMENT 
ABOUT A SHORT PERIOD OF SUSTAINED INTENSITY FOLLOWED BY GRADUAL 
WEAKENING AFTER TAU 36 AND THE JTWC INTENSITY FORECAST IS PLACED NEAR 
THE CONSENSUS WITH HIGH CONFIDENCE.

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