WDXS31 PGTW 150900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 07S (BAKUNG) WARNING NR 
008//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 10.9S 91.6E
   INITIAL INTENSITY: 50 KTS
   GEOGRAPHIC REFERENCE: 321 NM WEST-NORTHWEST OF THE COCOS ISLANDS
   MOVEMENT PAST 6 HOURS: EASTWARD AT 03 KTS
   SIGNIFICANT WAVE HEIGHT: 16 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A HIGHLY
ASYMMETRIC CIRCULATION WITH A PARTIALLY EXPOSED LOW LEVEL
CIRCULATION CENTER (LLCC) SITUATED IN THE NORTHEASTERN EDGE OF AN
AREA OF DISORGANIZED CONVECTION. ANIMATED WATER VAPOR IMAGERY
SHOWS AN AREA OF RELATIVELY DRY MID-LEVEL AIR ALONG THE
NORTHEASTERN FLANK OF THE CIRCULATION AND A SHARP UPSHEAR CLOUD
EDGE, FACING THE NORTHEASTERLY SHEAR. NOTWITHSTANDING THE LACK OF
RECENT MICROWAVE OR SCATTEROMETER DATA, THE INITIAL POSITION IS
ASSESSED WITH HIGH CONFIDENCE IN LIGHT OF THE PARTIALLY EXPOSED
LLCC IN THE MSI LOOP. THE INITIAL INTENSITY IS ASSESSED WITH MEDIUM
CONFIDENCE, BASED ON A BLEND OF THE AVAILABLE SUBJECTIVE AND
OBJECTIVE INTENSITY ESTIMATES NOTED BELOW. ENVIRONMENTAL CONDITIONS
HAVE DETERIORATED SIGNIFICANTLY OVER THE PAST DAY, WITH STRONG
DEEP-LAYER NORTHEASTERLY SHEAR, AND DRY AIR INTRUDING TO THE NORTH,
OFFSETTING THE STRONG POLEWARD OUTFLOW AND WARM SSTS.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: SOUTHERN PERIPHERY OF A NEAR EQUATORIAL
RIDGE (NER) POSITIONED ON AN EAST-WEST AXIS ALONG THE EQUATOR. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   APRF: T3.0 - 45 KTS
   CIMSS SATCON: 44 KTS AT 150740Z
   CIMSS ADT: 45 KTS AT 150530Z
   CIMSS AIDT: 51 KTS AT 150530Z
   CIMSS D-PRINT: 32 KTS AT 150740Z

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

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THE FORECAST HAS BEEN TRUNCATED TO 48
HOURS. 

FORECAST DISCUSSION: TROPICAL CYCLONE (TC) 07S CONTINUES TO DRIFT
SLOWLY EASTWARD ALONG THE SOUTHERN SIDE OF THE NER TO THE NORTH.
THIS GENERAL MOTION IS EXPECTED TO CONTINUE FOR THE NEXT 24 HOURS
AS THE NER REMAINS ENTRENCHED ALONG THE EQUATOR WEST OF SUMATRA.
HOWEVER, AS THE SYSTEM WEAKENS AFTER TAU 24, IT WILL STEADILY COME
UNDER THE INFLUENCE OF THE LOWER-LEVEL FLOW PATTERN, WHICH WILL
PUSH IT ONTO A NORTHWARD TRAJECTORY BY THE END OF THE FORECAST
PERIOD. IN TERMS OF INTENSITY, TC 07S IS FORECAST TO STEADILY
WEAKEN THROUGH THE FORECAST PERIOD DUE TO PERSISTENTLY HIGH
NORTHERLY SHEAR AND DRY AIR INTRUSION. THE SYSTEM IS EXPECTED TO
DISSIPATE AS A TROPICAL CYCLONE BY TAU 48. 

MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE IS ACTUALLY IN MUCH
BETTER AGREEMENT THAN IT WAS 24 HOURS AGO. ALL MEMBERS OF THE
CONSENSUS NOW AGREE THAT THE SYSTEM WILL TRACK EAST-NORTHEASTWARD
OVER THE NEXT 24 TO 36 HOURS BEFORE TURNING SHARPLY NORTHWARD BY
TAU 48. THE MAIN DISAGREEMENT BETWEEN THE MODELS IS JUST HOW FAR
EAST THE SYSTEM WILL GO PRIOR TO TURNING NORTHWARD. THE ECMWF-AIFS
AND ECEPS MEAN TRACK THE SYSTEM THE FURTHEST EAST BEFORE TURNING,
WHILE THE NAVGEM AND GFS TURN IT THE EARLIEST. THE RESULTING
CROSS-TRACK SPREAD IS A MODEST 110NM. THE JTWC FORECAST IS PLACED
NEAR THE GOOGLE DEEP MIND (GDM) AND ECWMF TRACKERS, WITH HIGH
CONFIDENCE. INTENSITY GUIDANCE IS ALSO IN GOOD AGREEMENT, WITH ALL
MESOSCALE MODELS INDICATING STEADY WEAKENING TO 30 KNOTS BY TAU 48.
THE SHIPS (BOTH NAVGEM AND GFS) HOWEVER BOTTOM OUT AT 35 KNOTS AT
TAU 36 AND HOLD FAST UNTIL TAU 60 WHEN THEY DEPICT A SLOW
INTENSIFICATION TREND. THE JTWC FORECAST IS PLACED NEAR THE CTCX
TRACKER WITH HIGH CONFIDENCE. 

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