WDXS33 PGTW 280900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 23S (HONDE) WARNING NR 
006//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 26.0S 43.8E
   INITIAL INTENSITY: 60 KTS
   GEOGRAPHIC REFERENCE: 301 NM SOUTHEAST OF EUROPA ISLAND
   MOVEMENT PAST 6 HOURS: EAST-SOUTHEASTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 30 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A BROAD
CIRCULATION WITH DEEP CONVECTIVE BANDING AND A VIBRANT SOUTHERN
OUTFLOW CHANNEL INTO THE SUBTROPICAL JET TO THE SOUTH. DRY AIR
BOUNDS THE WESTERN PERIPHERY OF THE SYSTEM AND WRAPS AROUND THE
NORTHERN PERIPHERY OF THE SYSTEM. THE INITIAL POSITION IS PLACED
WITH HIGH CONFIDENCE BASED ON THE AFOREMENTIONED ANIMATED MSI. THE
INITIAL INTENSITY OF 60 KTS IS ASSESSED WITH MEDIUM CONFIDENCE
BASED ON THE AGENCY AND OBJECTIVE FIXES LISTED BELOW.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: A COMPETING STEERING ENVIRONMENT
BETWEEN TWO SUBTROPICAL RIDGES.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   KNES: T3.5 - 55 KTS
   DEMS: T4.5 - 77 KTS
   FMEE: T4.5 - 77 KTS
   CIMSS SATCON: 54 KTS AT 280413Z
   CIMSS ADT: 37 KTS AT 280600Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 0-5 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: STRONG POLEWARD

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: TROPICAL CYCLONE (TC) 23S WILL REMAIN IN A
COMPETING STEERING ENVIRONMENT BETWEEN TWO RIDGES, RESULTING IN A
SLOW AND NEARLY QUASI-STATIONARY MOTION FOR THE FIRST 72 HOURS OF
THE FORECAST PERIOD. THE TRACK SPEED WILL INCREASE AS THE
SUBTROPICAL RIDGE TO THE WEST WEAKENS AND THE SYSTEM MOVES FARTHER
SOUTH UNDER THE INFLUENCE OF THE EASTERN RIDGE. THE SYSTEM WILL
GRADUALLY WEAKEN OVER THE COURSE OF THE FORECAST AS THE SLOW MOTION
CAUSES UPWELLING. OTHER FAVORABLE ENVIRONMENTAL FEATURES, SUCH AS
LOW VERTICAL WIND SHEAR AND UPPER-LEVEL DIVERGENCE, WILL COUNTER
THE UNFAVORABLE UPWELLING ALLOWING FOR A SLOWER RATE OF WEAKENING.

MODEL DISCUSSION: TC 23S HAS VARIED AGREEMENT BETWEEN THE
DETERMINISTIC MODELS DUE TO UNCERTAINTY WITHIN THE SLOW
QUASI-STATIONARY PERIOD. THIS MAY LEAD TO PERIODS OF LOOPING OR
IRREGULARITY IN THE NEAR-TERM BEFORE GETTING PICKED UP BY THE RIDGE
TO THE WEST. THE INTENSITY GUIDANCE IS SLIGHTLY SPREAD BETWEEN HWRF
AND JTWC SHIPS GUIDANCE, WHICH CAPTURE INTENSIFICATION IN THE FIRST
36 HOURS, AND THE REMAINDER OF THE MULTI-MODEL CONSENSUS, WHICH
CAPTURES STAGNATION OR WEAKENING. 

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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