WDXS31 PGTW 280300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 05S (DARIAN)     
WARNING NR 022//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.5S 79.2E
   INITIAL INTENSITY: 60 KTS
   GEOGRAPHIC REFERENCE: 840 NM SOUTH-SOUTHEAST OF DIEGO GARCIA
   MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 13 KTS
   SIGNIFICANT WAVE HEIGHT: 28 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL CYCLONE (TC) 05S HAS CONTINUED TO WEAKEN DUE TO PERSISTENT
NORTHERLY VERTICAL WIND SHEAR, COOLER SEA SURFACE TEMPERATURE AND
DRY AIR ENTRAINMENT AS EVIDENCED IN ANIMATED MULTISPECTRAL
SATELLITE IMAGERY, WHICH SHOWS AN EXPOSED LOW-LEVEL CIRCULATION
CENTER (LLCC) WITH RAPIDLY-DECAYING DEEP CONVECTION CONFINED TO THE
SOUTHERN SEMICIRCLE. DESPITE THE POOR DEEP CONVECTIVE STRUCTURE,
LOW-LEVEL BANDING CONTINUES TO WRAP TIGHTLY INTO A WELL-DEFINED
LLCC. ADDITIONALLY, A 272331Z SSMIS 37GHZ MICROWAVE IMAGE REVEALS
SHALLOW BANDING WRAPPING INTO A RAGGED BUT DEFINED LLCC, WHICH,
ALONG WITH THE MSI, SUPPORTS THE INITIAL POSITION WITH HIGH
CONFIDENCE. A RECENT 271953Z AMSR2 WINDSPEED IMAGE INDICATES AN
ASYMMETRIC WIND FIELD BUT SHOWS A SWATH OF 50-61 KNOT WINDS OVER
THE SOUTHERN QUADRANT, THEREFORE, THE INITIAL INTENSITY IS HELD AT
60 KNOTS. THIS ESTIMATE IS CONSISTENT WITH THE DVORAK CURRENT
INTENSITY ESTIMATES AS WELL AS THE CIMSS SATCON ESTIMATE.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: NORTHWESTERN PERIPHERY OF A DEEP-
LAYERED SUBTROPICAL RIDGE (STR) POSITIONED TO THE SOUTHEAST
AND SOUTH.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   KNES: T4.0 - 65 KTS
   FMEE: T4.0 - 65 KTS
   CIMSS SATCON: 60 KTS AT 272021Z
   CIMSS ADT: 51 KTS AT 280015Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 10-15 KTS
   SST: 25-26 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: MID- TO UPPER-LEVEL DRY AIR ENTRAINMENT

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TC 05S WILL TRACK STEADILY SOUTHWESTWARD
THROUGH TAU 48 ALONG THE NORTHWESTERN PERIPHERY OF THE STR. AFTER
TAU 48, THE SYSTEM WILL TURN SOUTH-SOUTHWESTWARD AS IT ROUNDS THE
WESTERN PERIPHERY OF THE STR. TC 05S WILL COMMENCE SUBTROPICAL 
TRANSITION NEAR TAU 48 AS IT ENCOUNTERS INCREASING NORTHWESTERLIES 
ALONG THE LEADING EDGE OF AN APPROACHING SUBTROPICAL TROUGH. 
INCREASING DRY AIR ENTRAINMENT AND COOLING SST (22-24C) WILL SERVE TO 
FURTHER WEAKEN THE SYSTEM. BY TAU 72, THE SYSTEM WILL BECOME EMBEDDED 
WITHIN THE SUBTROPICAL TROUGH AND COMPLETE SUBTROPICAL TRANSITION.   

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE REMAINS IN TIGHT AGREEMENT 
LENDING HIGH CONFIDENCE TO THE JTWC FORECAST TRACK. OVERALL, THIS 
FORECAST IS HIGHLY CONSISTENT WITH THE PREVIOUS TRACK FORECAST. 
INTENSITY GUIDANCE IS ALSO IN GOOD AGREEMENT WITH A 40-50 KNOT SPREAD 
IN GUIDANCE AT TAU 48-72. 

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