WDXS31 PGTW 142100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 07S (BAKUNG) WARNING NR 
007//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 10.9S 90.9E
   INITIAL INTENSITY: 70 KTS
   GEOGRAPHIC REFERENCE: 361 NM WEST-NORTHWEST OF THE COCOS ISLANDS
   MOVEMENT PAST 6 HOURS: SOUTHWARD AT 03 KTS
   SIGNIFICANT WAVE HEIGHT: 22 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
CYCLONE 07S (BAKUNG) WITH A HIGHLY COMPACT LOW-LEVEL CIRCULATION
CENTER (LLCC) AND STRONG BURSTS OF DEEP CONVECTION NEAR THE CENTER.
THE STRUCTURE HAS WORSEN OVER THE PAST 12 HOURS, WITH CLOUD TOPS
CONTINUING ON A WARMING TREND. THE INITIAL POSITION IS PLACED WITH
MEDIUM CONFIDENCE BASED ON THE ANIMATED EIR. THE INITIAL INTENSITY
OF 70 KTS IS ASSESSED WITH LOW CONFIDENCE DUE TO THE WIDE RANGE
BETWEEN AGENCY DVORAK FIXES AND OBJECTIVE INTENSITY ESTIMATES. THE
COMPACT NATURE OF THE VORTEX IS LIKELY CAUSING THE CIMSS ESTIMATES
TO BE UNDERESTIMATING INTENSITY. ENVIRONMENTAL ANALYSIS INDICATES
THAT 07S IS IN A MARGINAL ENVIRONMENT CHARACTERIZED BY MODERATE
POLEWARD OUTFLOW ALOFT, HIGH (20-25 KTS) NORTHEASTERLY VERTICAL
WIND SHEAR, AND WARM (27-28 C) SEA SURFACE TEMPERATURES.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: SOUTHWESTERN PERIPHERY OF A NEAR
EQUATORIAL RIDGE (NER) CENTERED NEAR SOUTHERN SUMATRA

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   APRF: T4.0 - 65 KTS
   CIMSS SATCON: 54 KTS AT 141857Z
   CIMSS ADT: 57 KTS AT 141730Z
   CIMSS AIDT: 45 KTS AT 141730Z
   CIMSS D-MINT: 43 KTS AT 141857Z
   CIMSS D-PRINT: 40 KTS AT 141900Z

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

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: SHORTENED THE FORECAST TO 72 HOURS
DUE TO AN EARLIER DISSIPATION

FORECAST DISCUSSION: 07S IS FORECAST TO TRACK SLOWLY EASTWARD ALONG
THE SOUTHERN EXTENT OF THE NER OVER THE NEXT 36-48 HOURS. AFTER TAU
48, THE SHALLOW VORTEX IS FORECAST TO DRIFT NORTHWARD, WITHIN THE
LOW-LEVEL STEERING PATTERN THROUGH TAU 72. TRACK CONFIDENCE REMAINS
LOW AND THE ACTUAL TRACK 07S TAKES COULD SIGNIFICANTLY DIFFER FROM
THE FORECAST DUE TO THE WEAK STEERING PATTERN. REGARDING INTENSITY,
THE HIGH NORTHEASTERLY SHEAR IS FORECAST TO STEADILY WEAKEN THE
VORTEX THROUGHOUT THE FORECAST PERIOD. DRY AIR ENTRAINMENT IS
EXPECTED TO INCREASE AFTER TAU 24, FURTHER AIDING IN WEAKENING THE
SYSTEM. DISSIPATION IS CURRENTLY FORECAST TO OCCUR AROUND TAU 72,
THOUGH IT COULD BE SOONER.

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE CONTINUES TO BE IN
POOR AGREEMENT WITH MODELS RANGING FROM A NORTHEASTWARD TRACK (GFS)
TO A SOUTHEASTWARD TRACK (ECMWF ENSEMBLE) STARTING FROM TAU 0.
CROSS-TRACK SPREAD AT TAU 48 IS AROUND 160 NM. THE JTWC TRACK
FORECAST IS PLACED CLOSER TO THE ECMWF DETERMINISTIC AND GOOGLE
DEEPMIND TRACKERS WITH LOW CONFIDENCE. INTENSITY GUIDANCE AGREES ON
STEADY WEAKENING THROUGHOUT THE FORECAST PERIOD. THE JTWC INTENSITY
FORECAST IS PLACED CLOSE TO THE MULTI-MODEL CONSENSUS WITH MEDIUM
CONFIDENCE.

FORECAST CONFIDENCE:
   TRACK 00-72 HR: LOW
   INTENSITY 00-72 HR: MEDIUM//
NNNN