WDXS31 PGTW 152100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 07S (BAKUNG) WARNING 
NR 009//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 10.9S 92.7E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 259 NM WEST-NORTHWEST OF THE COCOS ISLANDS
   MOVEMENT PAST 6 HOURS: EASTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
PARTIALLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) ON THE 
NORTHEASTERN PERIPHERY OF A NEARLYCIRCULAR BALL OF PERSISTENT DEEP 
CONVECTION. THIS TILT IS DUE TO NORTHEASTERLY SHEAR OF 20-25 KT. A 
MODERATE UPPER-LEVEL POLEWARD OUTFLOW CHANNEL IS OBSERVED. A 151435Z 
ASCAT-B SCATTEROMETER PASS REVEALED A COMPACT WIND FIELD WITH A RADIUS 
OF MAXIMUM WINDS OF 15 NM AND THE RADIUS OF GALE-FORCE WINDS SMALLER 
THAN 60 NM IN ALL QUADRANTS. THE INITIAL INTENSITY IS SET AT 45 KT 
BASED ON THIS ASCAT PASS AND A BLEND OF OBJECTIVE AND SUBJECTIVE 
SATELLITE-BASED INTENSITY ESTIMATES.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: NEAR-EQUATORIAL RIDGE TO THE NORTH

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   APRF: T3.0 - 45 KTS
   CIMSS ADT: 45 KTS AT 151730Z
   CIMSS AIDT: 39 KTS AT 151730Z
   CIMSS D-PRINT: 39 KTS AT 151730Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 20-25 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: MODERATE POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: HIGH

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TROPICAL CYCLONE 07S (BAKUNG) CONTINUES
TRACKING EASTWARD, INFLUENCED BY A DEEP-LAYER BELT OF EQUATORIAL
WESTERLIES TO THE NORTH AND SOME BINARY INTERACTION WITH A
SURFACE-LEVEL VORTICITY MAXIMUM NEARBY TO THE SOUTHEAST. THIS
BINARY INTERACTION MAY CONTRIBUTE TO A SLOWING OF 07S DURING TAU
12-24, FOLLOWED BY A NORTHWARD TURN DURING TAU 24-36. THIS MOTION
WILL ALSO BE INFLUENCED BY A MID-LEVEL NEAR-EQUATORIAL RIDGE
BUILDING IN TO THE NORTHWEST OF 07S. MODERATE NORTHERLY OR
NORTHEASTERLY SHEAR IS EXPECTED TO PERSIST DURING THIS PERIOD,
ALONG WITH DRY AIR ENCROACHMENT TO THE NORTHWEST AND SOUTHEAST,
GRADUALLY WEAKENING THE STORM. NUMERICAL MODELS ARE IN GOOD
AGREEMENT ON THIS TREND, AND THE JTWC FORECAST SHOWS WEAKENING
BELOW WARNING THRESHOLD BY TAU 36.

MODEL DISCUSSION: DYNAMICAL MODELS HAVE SOME TRACK SPREAD REGARDING
THE TIMING OF THE TURN NORTHWARD AND THE FORWARD SPEED OF THE
CYCLONE DURING THAT TIME. AI-BASED MODELS SHOW LESS OF A MOVE
TOWARDS THE NORTH, BUT MAY NOT RESOLVE THE BINARY INTERACTION WITH
THE NEIGHBORING VORTICITY MAXIMUM AS WELL AS THE PHYSICS-BASED
MODELS, WHICH MAINTAIN A TRACK JOG TOWARDS THE NORTH. THE JTWC
TRACK FORECAST LEANS CLOSER TO THE PHYSICAL MODELS. INTENSITY
FORECAST AIDS ARE IN TIGHT AGREEMENT ON GRADUAL WEAKENING, AND THE
JTWC FORECAST IS CLOSE TO THE MULTI-MODEL CONSENSUS.

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