WDXS31 PGTW 190900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 13S (DJOUNGOU)
WARNING NR 008//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 25.2S 85.5E
   INITIAL INTENSITY: 90 KTS
   GEOGRAPHIC REFERENCE: 1013 NM SOUTHWEST OF COCOS ISLANDS
   MOVEMENT PAST 6 HOURS: SOUTHEASTWARD AT 28 KTS
   SIGNIFICANT WAVE HEIGHT: 40 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
CYCLONE (TC) 13S (DJOUNGOU) EXHIBITING A RAPIDLY DETERIORATING
STRUCTURE DUE TO THE INFLUENCE OF VERY STRONG (35-40 KTS) VERTICAL
WIND SHEAR AND DRY AIR ENTRAINMENT OVER THE PAST TWELVE HOURS. DEEP
CONVECTION PERSISTS SOUTHEAST OF THE LLCC, SHOWING THE TC VORTEX TO
BE TILTED BUT STILL PROVIDING NECESSARY OUTFLOW. ENVIRONMENTAL
ANALYSIS SHOWS THE TC HAS CROSSED THE 26C ISOTHERM, REMOVING
NECESSARY WARM WATER INTAKE AT THE SURFACE. WITH MARGINALLY
FAVORABLE DIVERGENCE BEING THE ONLY SUPPORTING ENVIRONMENTAL FACTOR
FOR SUSTAINMENT, THE ENVIRONMENT IS ASSESSED AS UNFAVORABLE
OVERALL. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED
ON A 190600Z GEOSTATIONARY VISIBLE SATELLITE IMAGE SHOWING A MOSTLY
EXPOSED LOW LEVEL CIRCULATION CENTER. THE INITIAL INTENSITY OF 90
KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE SUBJECTIVE AND
OBJECTIVE INTENSITY ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: STR CENTERED OVER WESTERN AUSTRALIA

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   KNES: T6.0 - 115 KTS
   FMEE: T5.0 - 90 KTS
   FIMP: T5.5 - 102 KTS
   CIMSS SATCON: 91 KTS AT 190340Z
   CIMSS ADT: 92 KTS AT 190715Z
   CIMSS AIDT: 86 KTS AT 190715Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 30+ KTS
   SST: 26-27 CELSIUS
   OUTFLOW: STRONG EASTWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   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 13P IS FORECAST TO TRACK GENERALLY
EAST-SOUTHEASTWARD FROM TAU 00 TO TAU 36, FOLLOWING THE STEERING
INFLUENCE OF A DEEP-LAYER SUBTROPICAL RIDGE ANCHORED OVER
WEST-CENTRAL AUSTRALIA. WITH THE AFOREMENTIONED UNFAVORABLE
ENVIRONMENT IN PLAY, INTENSITY IS FORECAST TO RAPIDLY FALL AS THE
SYSTEM TRANSITIONS TO A SUBTROPICAL BY TAU 12, BECOMING
EXTRATROPICAL PRIOR TO TAU 36. A MODERATE TEMPERATURE GRADIENT AND
ELONGATION OF THE LLCC ALLUDE THE SUBTROPICAL TRANSITION HAS
COMMENCED. NEAR TAU 12, NUMERICAL MODELS AND STATISTICAL-DYNAMICAL
GUIDANCE SUGGEST DIVERGENCE ALOFT SHARPLY AND SIGNIFICANTLY
DECLINES, REMOVING THE LAST FAVORABLE ENVIRONMENTAL ELEMENT
SUPPORTING SUSTAINMENT OF THE SYSTEM.

MODEL DISCUSSION: GLOBAL NUMERICAL MODEL GUIDANCE IS IN EXCEPTIONAL
AGREEMENT REGARDING BOTH TRACK AND INTENSITY THROUGHOUT THE
FORECAST INTERVAL (TAU 00 TO TAU 36).  A CROSS-TRACK SPREAD OF
119NM (TAU 36) AND INTENSITY SPREAD OF 15KTS (TAU 36) CONTRIBUTE TO
THE OVERALL FORECAST CONFIDENCE OF HIGH. ALL GUIDANCE SUPPORTS A
RAPID DOWNTREND IN INTENSITY THROUGHOUT THE FORECAST INTERVAL AS
THE SYSTEM TRACKS EAST-SOUTHEASTWARD.

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   INTENSITY 0 - 72 HR: HIGH//
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