WDPN31 PGTW 300300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 06W (JANGMI) WARNING NR 
012//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 17.5N 130.1E
   INITIAL INTENSITY: 55 KTS
   GEOGRAPHIC REFERENCE: 555 NM SOUTH-SOUTHEAST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 28 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A BROAD
PARTIALLY EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) WITH
CONSOLIDATING CONVECTION NOW COMPLETELY SURROUNDING A NASCENT BROAD
EYE FEATURE. A 292113Z SENTINEL-1 SAR IMAGE REVEALED A WIND MINIMUM
AREA WITH A DIAMETER OF 60 NM SURROUNDED BY A WIND FIELD THAT HAS
EXHIBITED IMPROVING SYMMETRY OVER THE PAST 6 HOURS. THE INITIAL
POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE ANIMATED MSI
AND EXTRAPOLATION FROM THE PREVIOUSLY MENTIONED SAR IMAGE. THE
INITIAL INTENSITY OF 55 KTS IS ASSESSED WITH MEDIUM CONFIDENCE
BASED ON A BLEND OF THE SAR DATA, AGENCY DVORAK FIXES, AND CIMSS
INTENSITY ESTIMATES. THE CURRENT ENVIRONMENT IS ASSESSED TO BE
FAVORABLE FOR FURTHER INTENSIFICATION, WITH HIGH (29-30 C) SEA
SURFACE TEMPERATURES, MODERATE (10-15 KTS) EASTERLY VERTICAL WIND
SHEAR (VWS), AND MODERATE EQUATORWARD OUTFLOW ALOFT.

INITIAL WIND RADII BASIS: A 292113Z SENTINEL-1 SAR IMAGE 

CURRENT STEERING MECHANISM: SOUTHWESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) CENTERED NORTH OF THE MARIANA ISLANDS

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   RJTD: T3.0 - 45 KTS
   RCTP: T3.0 - 45 KTS
   KNES: T3.5 - 55 KTS
   CIMSS SATCON: 49 KTS AT 300000Z
   CIMSS ADT: 39 KTS AT 300000Z
   CIMSS AIDT: 39 KTS AT 300000Z
   CIMSS D-MINT: 53 KTS AT 292115Z
   CIMSS D-PRINT: 47 KTS AT 300000Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD

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: TROPICAL STORM (TS) 06W (JANGMI) IS FORECAST
TO CONTINUE ON A NORTHWESTWARD TRAJECTORY, TURNING GRADUALLY MORE
POLEWARD OVER THE NEXT 48 HOURS UNDER THE STEERING INFLUENCE OF THE
STR TO THE NORTHEAST. AFTER TAU 48, TS 06W WILL ROUND THE RIDGE
AXIS AND TURN ON A NORTHEASTWARD TRACK AS IT PASSES JUST WEST OF
OKINAWA SHORTLY BEFORE TAU 60. AFTER TAU 72, TS JANGMI IS FORECAST
TO SKIRT THE SOUTHERN COAST OF JAPANESE MAINLAND BEFORE EJECTING EAST 
OF TOKYO INTO THE NORTH PACIFIC. THE IMPROVING STRUCTURE OF THE STORM 
AND FAVORABLE ENVIRONMENTAL CONDITIONS ARE EXPECTED TO ALLOW FOR 
STEADY INTENSIFICATION TO A PEAK OF 85 KTS AT TAU 36. FOLLOWING THIS 
PEAK IN INTENSITY, COOLING SST AND INCREASING WESTERLY VWS WILL 
INDUCE A STEADY WEAKENING TREND THROUGH THE REMAINDER OF THE FORECAST 
PERIOD. INTERACTION WITH A POLAR FRONT JET STREAK AND ASSOCIATED 
BAROCLINIC FORCING WILL RESULT IN EXTRATROPICAL TRANSITION BEGINNING 
AROUND TAU 120, AT WHICH TIME TS 06W IS EXPECTED TO MAINTAIN A BROAD 
FIELD OF GALE FORCE WINDS.

MODEL DISCUSSION: MODEL TRACK GUIDANCE IS IN GOOD AGREEMENT ABOUT
THE RECURVING SCENARIO, WITH A CROSS-TRACK SPREAD OF 155 NM AT TAU
72. THE MODEL GUIDANCE IS SPLIT INTO TWO DISTINCT GROUPINGS, WITH
GOOGLE DEEPMIND AND EC-AIFS COMPRISING THE EASTERNMOST AND FASTEST
TRACKS OF THE GUIDANCE ENVELOPE. ALL OF THE PHYSICS-BASED MODELS
REMAIN CONFINED TO A TRACK TO THE WEST OF OKINAWA. THE JTWC TRACK
FORECAST IS PLACED NEAR THE MULTI-MODEL CONSENSUS WITH MEDIUM
CONFIDENCE THROUGHOUT THE ENTIRE FORECAST PERIOD. INTENSITY GUIDANCE 
IS ALSO SPLIT INTO TWO DISTINCT GROUPS, WITH MULTIPLE RAPID 
INTENSIFICATION (RI) AIDS SUGGESTING A PEAK INTENSITY 100-110
KTS WITHIN THE NEXT 36 HOURS. THE REMAINDER OF GUIDANCE SUGGESTS A
PEAK INTENSITY OF 70-80 KTS WITH A MORE GRADUAL PERIOD OF 
INTENSIFICATION. THE JTWC INTENSITY FORECAST IS PLACED ON THE
HIGHER END OF THE LATTER GROUPING OF GUIDANCE IN ACKNOWLEDGEMENT OF
THE POTENTIAL FOR RI TO OCCUR.

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