WDPN31 PGTW 302100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 06W (JANGMI) WARNING NR 015//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 20.1N 128.5E
   INITIAL INTENSITY: 65 KTS
   GEOGRAPHIC REFERENCE: 386 NM SOUTH OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 34 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A VERY
LARGE FRAGMENTED EYE FEATURE WITH AT LEAST TWO DISTINCT LOW-LEVEL
MESOVORTICIES EXPOSED WITHIN THE BROAD CORE. FLARING CONVECTION HAS
STRUGGLED TO FULLY WRAP INTO THE CORE OVER THE PAST 6 HOURS, 
PARTICULARLY IN THE WESTERN SEMICIRCLE WHERE A WEDGE OF DRY AIR HAS
INTRUDED. ANIMATED WATER VAPOR IMAGERY REVEALS IMPROVING POLEWARD
OUTFLOW WITH THE SUPPORT OF A JET STREAK ENTRANCE REGION OVER JAPAN
TO THE NORTH. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE
BASED ON THE CENTER OF THE FRAGMENTED EYE FEATURE IN ANIMATED EIR.
OVERALL, THE SATELLITE PRESENTATION HAS NOT SUGGESTED ANY SIGNIFICANT 
CHANGES IN THE SYSTEM'S STRUCTURE OVER THE PAST 6 HOURS, HOWEVER, 
LACKING ANY MICROWAVE IMAGERY PRECLUDES CONFIRMATION OF THIS 
ASSESSMENT. THE INITIAL INTENSITY OF 65 KTS IS ASSESSED WITH MEDIUM 
CONFIDENCE BASED ON THE AGENCY DVORAK FIXES AND CIMSS INTENSITY 
ESTIMATES LISTED BELOW. THE ENVIRONMENT IS CHARACTERIZED AS MARGINALLY 
FAVORABLE, WITH 28-29 C SEA SURFACE TEMPERATURES (SST), LOW VERTICAL 
WIND SHEAR, AND IMPROVING POLEWARD OUTFLOW ALOFT. THE BROADNESS OF THE 
SYSTEM AND WEAK DRY AIR ENTRAINMENT FROM THE WEST ARE CREDITED FOR THE 
OBSERVED LACK OF ANY RECENT INTENSIFICATION.

INITIAL WIND RADII BASIS: 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: T3.5 - 55 KTS
   KNES: T4.0 - 65 KTS
   CIMSS SATCON: 61 KTS AT 301800Z
   CIMSS AIDT: 59 KTS AT 301800Z
   CIMSS D-MINT: 63 KTS AT 301726Z
   CIMSS D-PRINT: 65 KTS AT 301800Z

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

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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: 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 NORTHWEST. 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 SHORTLY AFTER TAU 36 AS THE CENTER PASSES
JUST WEST OF OKINAWA. AFTER TAU 48, THE STEERING RIDGE IS EXPECTED
TO MIGRATE SOUTH AND SOUTHWESTWARD 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
MAINLAND JAPAN. EXTRATROPICAL TRANSITION IS EXPECTED TO BEGIN BY
TAU 96, WITH THE SYSTEM BECOMING FULLY EXTRATROPICAL BY TAU 120 AS
IT EXITS NORTHEASTWARD. MARGINALLY FAVORABLE ENVIRONMENTAL CONDITIONS 
SHOULD ALLOW A SMALL INCREASE IN INTENSITY OVER THE NEXT 12 HOURS TO A 
PEAK OF 70 KTS. COOLING SST AND INCREASING WESTERLY VWS AFTER TAU 36 
WILL AID IN GRADUAL WEAKENING THROUGH THE REMAINDER OF THE FORECAST 
PERIOD. 

MODEL DISCUSSION: MODEL TRACK GUIDANCE REMAINS IN TIGHT AGREEMENT
ABOUT THE RECURVING SCENARIO, WITH A CROSS-TRACK SPREAD OF 65 NM AT
TAU 72 AND 100 NM AT TAU 120. THERE REMAINS SOME UNCERTAINTY ABOUT
THE TRACK SPEED IN THE LATER TAUS, BUT THE ALONG-TRACK SPREAD HAS
DECREASED WITH THE LATEST MODEL RUN. THE JTWC TRACK FORECAST IS
PLACED VERY CLOSE TO THE MULTI-MODEL CONSENSUS WITH HIGH CONFIDENCE
THROUGH TAU 72 AND MEDIUM CONFIDENCE THEREAFTER. MODEL INTENSITY AIDS 
HAVE CONVERGED TO A TIGHT GROUPING IN THE LATEST MODEL RUN AS THERE 
WERE NO RAPID INTENSIFICATION AIDS THAT TRIGGERED. AS A RESULT, THE 
JTWC INTENSITY FORECAST IS PLACED CLOSE TO THE CONSENSUS WITH HIGH 
CONFIDENCE THROUGHOUT.

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