WDXS31 PGTW 070300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 21S (OLGA) WARNING NR 
006//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 14.5S 119.3E
   INITIAL INTENSITY: 75 KTS
   GEOGRAPHIC REFERENCE: 554 NM NORTH-NORTHEAST OF LEARMONTH,
AUSTRALIA
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 35 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS TC 21S
CONTINUED TO RAPIDLY CONSOLIDATE AND INTENSIFY WITH FEEDER BANDS 
WRAPPING TIGHTER TOWARD A DEFINED 17-NM EYE. A ROBUST POLEWARD OUTFLOW 
PERSISTS AS EVIDENCED BY EXTENSIVE CIRRUS STREAKS ALONG THE
SOUTHERN PERIPHERY. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON THE EYE FEATURE IN THE MSI LOOP, ADJUSTED FOR
FORWARD TILT AND LINED UP WITH A MICROWAVE EYE FEATURE IN THE
062234Z GPM 37GHZ IMAGE. THE INITIAL INTENSITY IS ALSO PLACED WITH
HIGH CONFIDENCE BASED ON THE HIGH END OF AGENCY AND AUTOMATED
DVORAK ESTIMATES AND REFLECTS THE RAPID 6-HR CONVECTIVE AND WRAP
IMPROVEMENT. ANALYSIS INDICATES A FAVORABLE ENVIRONMENT WITH
LIGHT-MODERATE VWS, STRONG OUTFLOW, AND WARM SST SLIGHTLY OFFSET BY
DRY AIR INTRUSION AT THE LOWER LEVELS ALONG THE WESTERN PERIPHERIES.

INITIAL WIND RADII BASIS: EXTRAPOLATED FROM RECENT SCATTEROMETER
DATA.

CURRENT STEERING MECHANISM: SOUTHWEST EXTENSION OF THE DEEP-LAYERED
SUBTROPICAL RIDGE (STR) TO THE EAST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   KNES: T5.0 - 90 KTS
   DEMS: T4.5 - 77 KTS
   APRF: T4.0 - 65 KTS
   CIMSS ADT: 70 KTS AT 070000Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG POLEWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TC OLGA WILL CONTINUE SOUTHWESTWARD ALONG THE
NORTHWEST EDGE OF THE SOUTHWEST EXTENSION OF THE STEERING STR. THE
FAVORABLE ENVIRONMENT WILL FUEL FURTHER INTENSIFICATION TO A PEAK
OF 80KTS BY TAU 12. AFTERWARD, INCREASING COLD DRY AIR INTRUSION AT
THE LOWER LEVELS, THEN LATER ON, INCREASING VWS AS THE CYCLONE
APPROACHES THE JET LEVEL WINDS ASSOCIATED WITH THE PREVAILING
WESTERLIES WILL COMBINE TO GRADUALLY WEAKEN THE SYSTEM LEADING TO 
DISSIPATION BY TAU 96. 

MODEL DISCUSSION: NUMERICAL WEATHER PREDICTION MODELS ARE IN
OVERALL GOOD AGREEMENT WITH NAVGEM THE SOLE LEFT OUTLIER TRACKING
THE VORTEX INTO THE STR AND TOWARD LEARMONTH - AN UNLIKELY SCENARIO.
THE MAIN PACK GRADUALLY AND EVENLY SPREADS OUT TO A MERE 120NM BY
TAU 72, LENDING HIGH CONFIDENCE TO THIS PORTION OF THE JTWC TRACK
FORECAST THAT IS LAID JUST TO THE RIGHT OF CONSENSUS TO OFFSET
NAVGEM. AFTERWARD, THE MODELS SIGNIFICANTLY DIVERGE ALONG- AND
ACROSS-TRACK, AN INDICATION OF A WEAK VORTEX UNDERGOING
DISSIPATION, LENDING LOW CONFIDENCE TO THE EXTENDED PORTION OF THE
JTWC TRACK FORECAST.

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