WDXS33 PGTW 270900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 23S (HONDE) WARNING NR 
004//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 24.9S 41.5E
   INITIAL INTENSITY: 70 KTS
   GEOGRAPHIC REFERENCE: 177 NM SOUTH-SOUTHEAST OF EUROPA ISLAND
   MOVEMENT PAST 6 HOURS: SOUTHEASTWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 57 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A BROAD
TROPICAL CYCLONE WITH DEEP CONVECTIVE BANDS WRAPPING INTO THE
LOW-LEVEL CIRCULATION CENTER (LLCC). STRONG POLEWARD AND MODERATE
EQUATORWARD OUTFLOW IS EVIDENT ON WATER VAPOR IMAGERY. THE INITIAL
POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON A 270600Z GPM GMI
89GHZ MICROWAVE IMAGE REVEALING THE BROAD SYSTEM CENTER AND DEEP
CONVECTIVE BANDING. THE INITIAL INTENSITY OF 70 KTS IS ASSESSED
WITH HIGH CONFIDENCE BASED ON THE AGENCY AND OBJECTIVE FIXES BELOW
ALONGSIDE A 270536Z METOP-B ASCAT WIND SPEED IMAGE.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: A COMPETING STEERING ENVIRONMENT
BETWEEN A SUBTROPICAL RIDGE TO THE WEST AND A RIDGE TO THE EAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   KNES: T3.5 - 55 KTS
   DEMS: T4.0 - 65 KTS
   CIMSS SATCON: 52 KTS AT 270439Z
   CIMSS ADT: 35 KTS AT 270600Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE POLEWARD AND EQUATORWARD

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

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 SLOWLY TRACK
SOUTHEASTWARD SLOWLY WHILE IN A COMPETING STEERING ENVIRONMENT FOR
THE ENTIRETY OF THE FORECAST PERIOD. IN THE NEAR-TERM, THE
DEEP-LAYER RIDGE TO THE EAST WILL INFLUENCE THE DIRECTION OF THE
SYSTEM, AND THE RIDGE TO THE WEST WILL SLOW THE TRACK SPEED. AFTER
TAU 72M, THE EASTERN RIDGE WILL BUILD AND FORCE THE SYSTEM TO CURVE
SOUTHWARD. THE SYSTEM WILL SLOWLY INTENSIFY TO A PEAK OF 80KTS
THROUGH THE FIRST 24 HOURS OF THE FORECAST WHILE VERTICAL WIND
SHEAR IS LOW, UPPER-LEVEL DIVERGENCE IS SUPPORTIVE, AND SEA SURFACE
TEMPERATURES ARE ABOVE 26 DEGREES. THE TRACK SPEED WILL SLOW
SIGNIFICANTLY BETWEEN TAU 24-36, RESULTING IN SIGNIFICANT
UPWELLING OF COOL WATER AND A LACK OF SUPPORT FOR FURTHER
INTENSIFICATION. THE SYSTEM WILL WEAKEN SLOWLY FOR THE REMAINDER OF
THE FORECAST PERIOD. 

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS VARIED BASED ON
DIFFERENT INTERPRETATIONS OF WHICH RIDGE TO THE EAST OR WEST WILL
BE STRONGER. IF THE WESTERN RIDGE OVERPOWERS THE STEERING, THE
TRACK WOULD RECURVE WESTWARD, AS REPRESENTED BY THE GFS, NAVGEM,
AND ECMWF. THE ENSEMBLES DEPICT REPRESENTATIONS MORE CLOSELY
ALIGNED TO THE FORECAST, WITH A SOUTHEASTWARD TRACK. THE INTENSITY
GUIDANCE IS IN GOOD AGREEMENT THAT REGARDLESS OF THE TRACK
DIRECTION, THE SYSTEM WILL WEAKEN AFTER A PEAK INTENSITY AT TAU 24.

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