WDXS32 PGTW 132100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 18S (EIGHTEEN) WARNING 
NR 011//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.3S 112.2E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 434 NM NORTH-NORTHWEST OF LEARMONTH,
AUSTRALIA
   MOVEMENT PAST 6 HOURS: EASTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS FLARING
CONVECTION SHEARED SOUTHWEST OF AND OBSCURING THE LOW LEVEL
CIRCULATION. THERE IS MINIMAL POLEWARD OUTFLOW AND NO ORGANIZED
FEEDER BANDS. ANALYSIS INDICATES A MARGINAL ENVIRONMENT WITH WARM
(29-30C) SST AND WEAK POLEWARD OUTFLOW ALOFT GREATLY OFFSET BY
STRONG (25-30 KTS) VERTICAL WIND SHEAR. THE INITIAL POSITION IS
PLACED WITH LOW CONFIDENCE BASED ON NOTCH FEATURE IN THE 131451Z
AMSU-B MICROWAVE IMAGE. THE INITIAL INTENSITY IS ALSO PLACED WITH
LOW CONFIDENCE BASED ON PERSISTENCE AND HELD HIGHER THAN AGENCY AND
OBJECTIVE DVORAK INTENSITY ESTIMATES.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: SOUTHERN PERIPHERY OF A NEAR EQUATORIAL
RIDGE (NER) TO THE NORTH.


AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   DEMS: T2.0 - 30 KTS
   APRF: T1.5 - 25 KTS
   CIMSS SATCON: 43 KTS AT 131730Z
   CIMSS ADT: 32 KTS AT 131730Z
   CIMSS AIDT: 32 KTS AT 131730Z
   CIMSS DPRINT: 25 KTS AT 13800Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 25-30 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: WEAK POLEWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TC 18S WILL CONTINUE EAST-SOUTHEASTWARD UNDER
THE NER. AFTER TAU 36, SUBTROPICAL RIDGE TO THE EAST, ANCHORED OVER
AUSTRALIA, WILL ASSUME STEERING AND DRIVE THE SYSTEM SOUTHWARD THEN
SOUTH-SOUTHWESTWARD, AS THE STORM MOTION BECOME MORE IN-PHASE WITH
THE UPPER-LEVEL WIND FLOW, VWS IS EXPECTED TO WEAKEN AND POLEWARD
OUTFLOW TO IMPROVE, PROMOTE A STEADY INTENSIFICATION, AND BY TAU
120 WILL REACH 80KTS AS IT COMES TO WITHIN 140NM OF LEARMONTH. 

MODEL DISCUSSION: NUMERICAL MODELS REMAIN IN POOR AGREEMENT
UNEVENLY SPREADING OUT TO 195NM AT TAU 72 AND 287NM AT TAU 120.
THIS PLUS THE UNCERTAINTIES IN THE STORM POSITIONING, LEND OVERALL
LOW CONFIDENCE TO THE JTWC TRACK FORECAST. 

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: LOW
   TRACK 72-120 HR: LOW
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
NNNN