WDXS32 PGTW 232100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 06S (ANGGREK) WARNING 
NR 018//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 13.5S 91.5E
   INITIAL INTENSITY: 50 KTS
   GEOGRAPHIC REFERENCE: 1185 NM EAST-SOUTHEAST OF DIEGO GARCIA
   MOVEMENT PAST 6 HOURS: SOUTH-SOUTHWESTWARD AT 02 KTS
   SIGNIFICANT WAVE HEIGHT: 20 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS DEEP
CONVECTIVE BANDING REDEVELOPING OVER A COMPACT LOW-LEVEL
CIRCULATION. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE
BASED ON 231527Z METOP-C 89 GHZ DATA AND THE 231730Z PGTW SATELLITE
FIX. THE INITIAL INTENSITY OF 50 KTS IS ASSESSED WITH HIGH
CONFIDENCE CONSISTENT WITH A NARROW RANGE OF MULTI-AGENCY
SUBJECTIVE DVORAK AND AUTOMATED INTENSITY ESTIMATES (45-55 KNOTS).
THE RECENT IMPROVEMENT IN CONVECTIVE SIGNATURE MAY BE ATTRIBUTABLE
TO OBSERVED INCREASING POLEWARD OUTFLOW AND MOVEMENT AWAY FROM A
COOL PATCH OF PREVIOUSLY UPWELLED WATER.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: WEAK SUBTROPICAL RIDGING TO THE SOUTH
AND EAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   KNES: T3.5 - 55 KTS
   CIMSS SATCON: 49 KTS AT 231655Z
   CIMSS ADT: 53 KTS AT 231730Z
   CIMSS D-PRINT: 52 KTS AT 231800Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: MODERATE POLEWARD

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: FORECAST INTENSITIES IN THE EXTENDED
PERIOD HAVE INCREASED BY ABOUT 20 KNOTS RELATIVE TO THE PREVIOUS
FORECAST CONSISTENT WITH CHANGES IN THE NUMERICAL FORECAST GUIDANCE 
PACKAGE. HOWEVER, THE OVERALL FORECAST PHILOSOPHY HAS NOT CHANGED 
SIGNIFICANTLY.

FORECAST DISCUSSION: TC 06S WILL TRACK SOUTHWESTWARD TO
WEST-SOUTHWESTWARD THROUGH THE DURATION OF THE FORECAST ALONG THE
NORTHERN PERIPHERY OF BUILDING SUBTROPICAL RIDGING TO THE SOUTH AND
EAST. TRANSLATIONAL SPEED WILL INCREASE STEADILY AS THE STEERING
RIDGE BUILDS. WITH POLEWARD OUTFLOW INCREASING AND THE SYSTEM
MOVING OVER WARMER WATER, STEADY NEAR-TERM INTENSIFICATION IS
LIKELY. IN THE EXTENDED RANGE, A MORE RESTRICTED OUTFLOW PATTERN
AND SLIGHT INCREASE IN VERTICAL WIND SHEAR IS EXPECTED TO HALT THE
INTENSIFICATION TREND.  

MODEL DISCUSSION: BOTH DETERMINISTIC AND ENSEMBLE MODEL FORECASTS
ARE IN VERY GOOD AGREEMENT REGARDING THE TRACK, PARTICULARLY FOR
THE FIRST 72 HOURS OF THE FORECAST PERIOD, REFLECTING THE
RELATIVELY STRAIGHTFORWARD STEERING PATTERN. IN CONTRAST, INTENSITY
FORECAST GUIDANCE DIVERGES SIGNIFICANTLY, WITH HAFS AND COAMPS-TC
INDICATING THE POTENTIAL FOR PRONOUNCED INTENSIFICATION AT
DIFFERENT POINTS IN THE FORECAST PERIOD AND THE REMAINDER OF THE
GUIDANCE PREDICTING A SMOOTHER INTENSIFICATION TREND AS REFLECTED
IN THE CURRENT JTWC OFFICIAL FORECAST. RAPID DEVIATIONS IN
INTENSITY ARE NOT UNUSUAL FOR A SMALL SYSTEM LIKE TC 06S, SO
ADDITIONAL UPDATES TO THE INTENSITY FORECAST MAY BE WARRANTED IN
SUBSEQUENT FORECASTS.


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