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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