WDXS31 PGTW 300900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 01S (ONE) WARNING NR 
004//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 13.7S 93.2E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 234 NM WEST-SOUTHWEST OF COCOS ISLANDS,
AUSTRALLIA
   MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 14 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A
MEDIUM-SIZED SYSTEM THAT HAS MAINTAINED OVERALL STRUCTURE IN THE
PAST 12HRS, CHARACTERIZED BY FLARING CENTRAL CONVECTION AND SHEARED
CIRRI CANOPY ALONG THE SOUTHERN PERIPHERIES. THE INITIAL POSITION
IS PLACED WITH LOW CONFIDENCE USING LOW CLOUD TRACING IN THE MSI
LOOP SANS RECENT SCATTEROMETRY DATA AND GOOD MICROWAVE IMAGERY. THE
INITIAL INTENSITY OF 40KTS IS PLACED WITH MEDIUM CONFIDENCE BASED
ON THE HIGH END OF AGENCY AND AUTOMATED DVORAK ESTIMATES AND
REFLECTS THE SUSTAINED STRUCTURE. ENVIRONMENTAL CONDITIONS REMAIN
MARGINALLY FAVORABLE WITH STRONG POLEWARD OUTFLOW AND TEPID SST
OFFSET BY MODERATE TO HIGH NORTHERLY VERTICAL WIND SHEAR.

INITIAL WIND RADII BASIS: PERSISTENCE.

CURRENT STEERING MECHANISM: NORTHWEST PERIPHERY OF A LOW- TO
MID-LEVEL EXTENSION OF THE SUBTROPICAL RIDGE (STR) TO THE
SOUTHEAST.  


AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   CIMSS ADT: 41 KTS AT 300550Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 20-25 KTS
   SST: 26-27 CELSIUS
   OUTFLOW: STRONG POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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 01S IS APPROACHING A BREAK IN THE STEERING
STR CAUSED BY A DEEP MIDLATITUDE TROUGH TRANSITING FROM SOUTHWEST.
AFTER TAU 12, AS THE MIDLATITUDE TROUGH RECEDES EASTWARD, A
SECONDARY STR WILL BUILD TO THE SOUTH, ASSUME STEERING, AND DRIVE
THE SYSTEM WEST-NORTHWESTWARD. TC 01S WILL MAINTAIN ITS CURRENT
INTENSITY OVER THE NEXT 12 HOURS UNDER THE MARGINALLY FAVORABLE
ENVIRONMENT. AFTERWARD, CONDITIONS WILL DEGRADE STEADILY WITH
STRONG DRY AIR ENTRAINMENT, INCREASING VWS AND SUSTAINED
MARGINALLY-FAVORABLE SST VALUES, LEADING TO DISSIPATION BY 48.   

MODEL DISCUSSION: NUMERICAL MODELS ARE IN TIGHT AGREEMENT WITH A
MERE 55NM SPREAD IN SOLUTIONS AT TAU 48 LENDING HIGH CONFIDENCE TO
THE JTWC TRACK FORECAST. 

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