WDXS31 PGTW 191500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 05S (DARIAN) WARNING 
NR 004//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 12.7S 93.5E
   INITIAL INTENSITY: 75 KTS
   GEOGRAPHIC REFERENCE: 200 NM WEST OF THE COCOS ISLANDS
   MOVEMENT PAST 6 HOURS: SOUTH-SOUTHEASTWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 24 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A MARKED
INCREASE IN CONVECTION WRAPPING AROUND A NASCENT RAGGED EYE FEATURE.
ALTHOUGH TC 05S HAS BECOME MORE ORGANIZED OVER THE PAST SIX HOURS,
MOST ASSOCIATED DEEP CONVECTION IS CONFINED TO THE WESTERN PORTION
OF THE CIRCULATION. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON A CLEAR MICROWAVE EYE EVIDENT IN 191231Z 37 GHZ
SSMIS IMAGERY. THE INITIAL INTENSITY OF 75 KTS IS ASSESSED WITH
HIGH CONFIDENCE BASED ON SUBJECTIVE DVORAK ESTIMATES OF T4.5 FROM
PGTW, KNES AND APRF AS WELL AS SUPPORTIVE AUTOMATED ADT AND AIDT
DATA FROM UW-CIMSS.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: NEAR EQUATORIAL RIDGE TO THE NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   KNES: T4.5 - 77 KTS
   APRF: T4.5 - 77 KTS

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 5-10 KTS
   SST: 26-27 CELSIUS
   OUTFLOW: MODERATE POLEWARD

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: FORECAST INTENSITIES HAVE BEEN
INCREASED BASED ON THE RECENT TREND AND LATEST MODEL GUIDANCE. 
HOWEVER, THE OVERALL FORECAST PHILOSOPHY HAS NOT CHANGED FROM THE 
PREVIOUS WARNING.

FORECAST DISCUSSION: TC 05S WILL TRACK POLEWARD FOR THE NEXT 12 TO
24 HOURS UNDER THE CONTINUED STEERING INFLUENCE OF THE NEAR
EQUATORIAL RIDGE TO THE NORTHEAST. THEREAFTER, TC 05S WILL TURN 
WESTWARD AS A BUILDING SUBTROPICAL RIDGE TO THE SOUTH BECOMES THE 
DOMINANT STEERING MECHANISM FOR THE REMAINDER OF THE FORECAST PERIOD. 
ADDITIONAL INTENSIFICATION IS EXPECTED IN THE NEXT 12 HOURS DUE TO 
FAVORABLE UPPER-LEVEL FLOW. HOWEVER, UPWELLING OF COOLER WATER, NOW 
DRIVEN BY A MORE INTENSE AND STILL SLOW-MOVING SYSTEM, IS EXPECTED TO 
TEMPER THE INTENSIFICATION TREND. AFTER TAU 12, A MORE RESTRICTED 
OUTFLOW PATTERN AND PASSAGE OVER MARGINAL SEA SURFACE TEMPERATURES 
SHOULD PRODUCE A BIT OF WEAKENING. BUT ANOTHER INCREASE IN INTENSITY 
IS POSSIBLE LATE IN THE FORECAST PERIOD AS THE SYSTEM DIPS POLEWARD
DUE TO A REORIENTATION OF THE STEERING RIDGE AND OUTFLOW AGAIN 
IMPROVES.

MODEL DISCUSSION: MODEL DISCUSSION: NUMERICAL MODELS REMAIN IN 
AGREEMENT REGARDING THE OVERALL FORECAST SCENARIO OF INITIALLY 
POLEWARD MOTION IN THE NEAR-TERM, FOLLOWED BY A WESTWARD TURN AFTER 
TAU 24. THE CURRENT TRACK FORECAST LIES WITHIN THE CONSENSUS MODEL 
GROUPING NEAR THE MULTI-MODEL CONSENSUS THROUGH TAU 72. MODEL SPREAD 
INCREASES THEREAFTER, REFLECTING UNCERTAINTY REGARDING THE EXACT 
ORIENTATION OF THE STEERING RIDGE TO THE SOUTH OF THE SYSTEM. 
HOWEVER, THE MAJORITY OF CONSENSUS MODELS KEEP THE RIDGE FIRMLY IN 
PLACE, IN AN ORIENTATION THAT ALLOWS FOR A SLIGHT POLEWARD DIP IN THE 
STORM TRACK LATE IN THE FORECAST PERIOD. CONSENSUS MODEL INTENSITY 
FORECAST GUIDANCE IS IN FAIR AGREEMENT WITH THE GENERAL SCENARIO OF 
ADDITIONAL INTENSIFICATION OVER THE NEXT 24 HOURS, FOLLOWED BY A 
PERIOD OF WEAKENING AND ANOTHER ROUND OF MODEST INTENSIFICATION IN 
THE EXTENDED PERIOD. HOWEVER, SPREAD INCREASES BETWEEN SHIPS MODEL 
SOLUTIONS ON THE LOWER END (AROUND 45 KNOTS) AND HWRF ON THE UPPER 
END (AROUND 85 KNOTS) BY TAU 120.

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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