WDXS31 PGTW 040900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 04S (FOUR) WARNING NR 
002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 9.8S 92.9E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 268 NM NORTHWEST OF COCOS ISLAND
   MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 14 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A COMPACT
CIRCULATION, WHICH HAS BECOME FULLY EXPOSED, AFTER HAVING
BEEN OBSCURED TO PARTIALLY OBSCURED OVER THE PREVIOUS 12 HOURS. THE
LOW-LEVEL CIRCULATION CENTER (LLCC) IS EMBEDDED WITHIN A LARGER
REGION OF CYCLONIC ROTATION, OUTLINED BY AREAS OF FLARING
CONVECTION, PARTICULARLY ON THE SOUTHWESTERN PERIPHERY.
UNFORTUNATELY, THERE IS NO USEFUL ASCAT OVER THE PAST SIX HOURS,
HOWEVER THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE VIA
ANIMATED MSI. THE INITIAL INTENSITY IS SET AT 35 KNOTS WITH MEDIUM
CONFIDENCE BASED ON THE A COMBINATION OF FIXING AGENCIES, AS WELL
AS OBJECTIVE DVORAK INTENSITY ESTIMATES. ENVIRONMENTAL CONDITIONS
ARE MARGINAL, AND NOT HIGHLY FAVORABLE, WITH WARM (27-28C) SEA
SURFACE TEMPERATURES (SSTS), MODERATE POLEWARD OUTFLOW, OFFSET BY
MODERATE (15-20) NORTHEASTERLY VERTICAL WIND SHEAR (VWS).

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A DEEP-LAYER STR
CENTERED TO THE EAST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.5 - 25 KTS
   KNES: T2.0 - 30 KTS
   CIMSS SATCON: 39 KTS AT 040130Z
   CIMSS ADT: 35 KTS AT 040540Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 15-20 KTS
   SST: 27-28 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: AFTER HAVING BEEN PARTIALLY OBSCURED OVER THE
PAST 12 HOURS. THE CURRENT ANIMATED MULTI-SPECTRAL IMAGERY (MSI)
SHOWS THAT THE LOW-LEVEL CIRCULATION CENTER (LLCC) HAS BECOME FULLY
EXPOSED AND RESIDES TO THE NORTHEAST OF THE FLARING CONVECTION, AS
NORTHEASTERLY SHEAR HAS DECOUPLED THE CONVECTION FROM THE LOW
LEVEL. TC 04S IS CURRENTLY TRACKING GENERALLY SOUTHWEST ALONG THE
WESTERN SIDE OF THE STR TO THE EAST. OVER THE NEXT 24-36 HOURS THE
STR TO THE EAST WILL DIRECT THE SYSTEM SOUTHWESTERLY, BEFORE A DEEP
STR WILL SET UP TO THE SOUTH OF THE SYSTEM CENTERED NEAR 20S 80E.
IN RESPONSE, TC 04W WILL THEN TRACK IN A MORE GENERAL WESTWARD
DIRECTION THROUGHOUT THE FORECAST PERIOD. TC 04W WILL LIKELY
STRUGGLE TO INTENSIFY OVER THE NEXT 24-36 HOURS AS MODERATE
VERTICAL WIND SHEAR (VWS) WILL CONTINUE TO BE THE LIMITING FACTOR,
LIKELY RESULTING IN ROUNDS OF CONVECTIVE BLOW OFF. HOWEVER, THE
SYSTEM TAPS INTO A SLIGHTLY MORE FAVORABLE UPPER-LEVEL ENVIRONMENT
AFTER TUA 36, AND THUS THE SYSTEM COULD SLIGHTLY INTENSIFY.
THEREAFTER, TC 04W WILL LIKELY REMAIN IN A STEADY STATE UNTIL TAU
96, BEFORE SHEAR STARTS TO INCREASE ONCE MORE ALONG WITH INCREASING
DRY AIR ENTRAINMENT. THEREFORE, THE JTWC FORECAST CALLS FOR
DISSIPATION BY TAU 120, WITH A REMNANT CIRCULATION IS LIKELY TO
PERSIST BEYOND THE FORECAST PERIOD.         

MODEL DISCUSSION: DETERMINISTIC AND ENSEMBLE TRACK GUIDANCE REMAINS
IN GOOD AGREEMENT WITH MINIMAL SPREAD IN TRACK SOLUTIONS THROUGHOUT
THE FORECAST PERIOD.  THEREFORE, THE JTWC TRACK FORECAST IS PLACED
WITH HIGH CONFIDENCE, CLOSE TO THE MULTI-MODEL CONSENSUS, AND
SIMILAR TO THE PREVIOUS FORECAST TRACK. INTENSITY GUIDANCE REMAINS
MIXED, WITH THE HWRF AND COTI SHOWING WEAK INTENSIFICATION. THE
REMAINDER OF THE CONSENSUS MEMBERS SHOW A STEADIER INTENSIFICATION
TO AROUND TUA 72, WITH A GRADUAL DECREASE AFTERWARDS. THE JTWC
FORECAST FOLLOWS CLOSE TO THE MULTI-MODEL CONSENSUS THROUGH TUA 72
AND SLIGHTLY BELOW THE MEAN THEREAFTER.

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