WDXS33 PGTW 020900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 23S (HONDE) WARNING NR 
010//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 27.1S 46.0E
   INITIAL INTENSITY: 65 KTS
   GEOGRAPHIC REFERENCE: 432 NM SOUTHEAST OF EUROPA ISLAND
   MOVEMENT PAST 6 HOURS: EASTWARD AT 01 KTS
   SIGNIFICANT WAVE HEIGHT: 25 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A CURRENTLY
QUASI-STATIONARY TROPICAL CYCLONE (TC) 23S (HONDE) SHOWING SIGNS OF
MINOR INTENSIFICATION OVER THE LAST 6 HOURS. AS THE SYSTEM
CONTINUED TO SLOW DOWN, ITS SPIRAL BANDING STRUCTURE CONSOLIDATED,
FORMING A TIGHT CONVECTIVE CANOPY. ENVIRONMENTAL ANALYSIS REVEALS A
MARGINALLY FAVORABLE ENVIRONMENT WITH WARM (26-27 C) SEA SURFACE
TEMPERATURES (SST), STRONG POLEWARD OUTFLOW, LOW (10-15 KTS)
VERTICAL WIND SHEAR, OFFSET ONLY BY THE PRESENCE OF DRY AIR ALONG
WESTERN, NORTHERN AND EASTERN PERIPHERIES OF THE SYSTEM. THE
INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON 020319Z
F16 SSMIS 37 GHZ MICROWAVE IMAGE REVEALING THE LOW-LEVEL
CIRCULATION CENTER (LLCC). THE INITIAL INTENSITY OF 65 KTS IS
ASSESSED WITH MEDIUM CONFIDENCE BASED ON IMPROVED STRUCTURE OF THE
SYSTEM, AS INDICATED BY THE AGENCY DVORAK AND OBJECTIVE INTENSITY
AIDS LISTED BELOW.

INITIAL WIND RADII BASIS: SAR DATA 

CURRENT STEERING MECHANISM: COMPETING STEERING ENVIRONMENT WITH TWO
SUBTROPICAL RIDGES (STR) LOCATED TO THE WEST AND EAST OF THE SYSTEM

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   KNES: T4.5 - 77 KTS
   DEMS: T4.0 - 65 KTS
   CIMSS SATCON: 66 KTS AT 020323Z
   CIMSS ADT: 77 KTS AT 020600Z
   CIMSS AIDT: 80 KTS AT 020500Z
   CIMSS D-MINT: 64 KTS AT 020321Z
   CIMSS D-PRINT: 61 KTS AT 020600Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 10-15 KTS
   SST: 26-27 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: DRY AIR SURROUNDING THE SYSTEM, WITH THE SOURCE
OVER THE WESTERN SEMICIRCLE 

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: AS THE SYSTEM BECAME
QUASI-STATIONARY, MARGINALLY FAVORABLE ENVIRONMENTAL CONDITIONS
ALLOWED FOR MINOR INTENSIFICATION 

FORECAST DISCUSSION: AS THE TC 23S IS EMBEDDED WITHIN A COMPETING
STEERING ENVIRONMENT, IT IS FORECAST TO SLOWLY, AND SOMEWHAT
ERRATICALLY, TRANSIT EASTWARD OVER THE NEXT 12-24 HOURS.
AFTERWARDS, THE STR TO THE EAST WILL ASSUME PRIMARY STEERING,
GUIDING TC HONDE SOUTHWARD. THE SYSTEM SPEED OVER WATER WILL
SIGNIFICANTLY INCREASE AS IT ROUNDS THE SOUTHWESTWARD PERIPHERY OF
THE STR. SIMULTANEOUSLY, BY TAU 72, TC 23S IS FORECAST TO BEGIN
INTERACTING WITH THE BAROCLINIC ZONE, TRANSITIONING TO AN
EXTRATROPICAL SYSTEM BY TAU 96. AS THE SYSTEM TRANSITS SOUTH, DRY AIR 
INTRUSION WILL REMAIN THE MAIN UNFAVORABLE COMPONENT OF THE 
ENVIRONMENT, CAUSING A STEADY, BUT SLOW WEAKENING. AS THE SYSTEM 
COMPLETES THE EXTRATROPICAL TRANSITION BY TAU 96, IT IS FORECAST TO 
FURTHER WEAKEN DOWN TO 45 KTS.

MODEL DISCUSSION: NUMERICAL TRACK MODEL GUIDANCE IS IN FAIR
AGREEMENT, WITH ALL MODELS PREDICTING A SOUTHWARD TURN TO BE
COMPLETED BY TAU 24, FOLLOWED BY A SOUTH AND SOUTH-EASTWARD MOVEMENT 
TOWARDS THE END OF THE FORECAST PERIOD. JTWC TRACK FORECAST IS 
ASSESSED WITH MEDIUM CONFIDENCE DUE TO THE DIFFERENCE IN THE TIMELINE 
AND RATE OF THE INITIAL TURN, WITH SOME MODELS (NAVGEM, GALWEM, UKMET 
AND UKMET ENSEMBLE) SUGGESTING A BROADER AND SLOWER TURN, WHILE OTHERS 
(GFS, ECMWF, ECMWF ENSEMBLE) RECOMMENDING A SHARPER AND QUICKER 
TRANSITION. THE RELATIVELY SUBTLE DIFFERENCES IN THE INITIAL TRACK 
WILL HAVE IMPACTS ON THE ABILITY OF THE SYSTEM TO MAINTAIN INTENSITY. 
JTWC INTENSITY FORECAST IS THEREFORE ASSESSED WITH MEDIUM CONFIDENCE 
AS WELL, WITH ALL MODELS PREDICTING A GENERAL WEAKENING TREND 
BEGINNING AS SOON AS THE NEXT TAU. GFS IS THE MOST AGGRESSIVE, WITH 
IMMEDIATE INTENSITY DROP, WHILE OTHER MODELS, LIKE HAFS OFFER A MORE 
GRADUAL TREND. 

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