WDPS31 PGTW 260300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 18P (ALFRED) WARNING NR 
010//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 14.8S 155.0E
   INITIAL INTENSITY: 75 KTS
   GEOGRAPHIC REFERENCE: 306 NM EAST-NORTHEAST OF WILLIS ISLAND,
AUSTRALIA
   MOVEMENT PAST 6 HOURS: SOUTHWARD AT 02 KTS
   SIGNIFICANT WAVE HEIGHT: 32 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS THE SYSTEM
HAS BEGUN TO TRACK POLEWARD AFTER COMING OUT OF A SLOW LOOPING MOTION
IN A COL BETWEEN THE NEAR EQUATORIAL RIDGE TO THE NORTH AND THE
STEERING STR TO THE NORTHEAST. THE SYSTEM HAS MOSTLY MAINTAINED ITS
CONVECTIVE STRUCTURE AS THE FAVORABLE ENVIRONMENT IS OFFSET BY
LOCALIZED COOLER SST DUE TO UPWELLING IN THE COL. THE INITIAL
POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON A MICROWAVE EYE IN
THE 251658Z SSMIS 37GHZ IMAGE. THE INITIAL INTENSITY IS BASED ON
THE HIGH END OF AGENCY ESTIMATES TO REFLECT THE SUSTAINED 12-HR 
CONVECTIVE STRUCTURE. ANALYSIS INDICATES A MARGINALLY FAVORABLE 
ENVIRONMENT WITH LOW VWS,  AND MODERATE POLEWARD OUTFLOW OFFSET BY THE 
LOCALIZED COOL SST.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA.

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE
NORTHEAST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   KNES: T4.5 - 77 KTS
   ABRF: T4.0 - 65 KTS
   CIMSS ADT: 59 KTS AT 252330Z

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

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: MEDIUM
   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 ALFRED WILL CONTINUE TO TRACK SOUTHWARD
UNDER THE STEERING INFLUENCE OF THE STR TO THE NORTHEAST. AFTER TAU
72, AN THE STR WILL REORIENT AND BUILD TO THE EAST AND DRIVE THE
CYCLONE SOUTHWESTWARD. THE MARGINALLY FAVORABLE ENVIRONMENT WILL
MAINTAIN THE CURRENT INTENSITY UP TO TAU 36; AFTERWARD, A MODEST
INTENSIFICATION TO A PEAK OF 80KTS BY TAU 48 IS EXPECTED AS
POLEWARD OUTFLOW INCREASES. WEAKENING WILL COMMENCE AFTER TAU 48
DUE TO INCREASING VWS, REDUCING THE SYSTEM TO 65KTS BY TAU 120 AS
IT APPROACHES THE CENTRAL EAST COAST OF AUSTRALIA. 

MODEL DISCUSSION: NUMERICAL MODELS ARE IN OVERALL GOOD AGREEMENT
WITH A GRADUAL SPREAD TO 118NM BY TAU 72, LENDING MEDIUM CONFIDENCE
TO THIS PORTION OF THE JTWC TRACK FORECAST; THEN TO A MUCH WIDER
SPREAD OF 320NM BY TAU 120, LENDING LOW CONFIDENCE TO THE EXTENDED
PORTION OF THE TRACK FORECAST.   

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