WDXS33 PGTW 260900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 23S (HONDE) WARNING NR 
002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 23.4S 38.8E
   INITIAL INTENSITY: 50 KTS
   GEOGRAPHIC REFERENCE: 106 NM SOUTHWEST OF EUROPA ISLAND
   MOVEMENT PAST 6 HOURS: SOUTH-SOUTHEASTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 21 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A BROADLY
ORGANIZED TROPICAL CYCLONE (TC) 23S (HONDE) WITH SPIRAL BANDS OF
FLARING, DEEP CONVECTION WRAPPING INTO THE LOW-LEVEL CIRCULATION
CENTER (LLCC). ENVIRONMENTAL CONDITIONS ARE FAVORABLE FOR
INTENSIFICATION, WITH WARM (29-30) SEA SURFACE TEMPERATURES (SST) AND
LOW (0-5 KTS) VERTICAL WIND SHEAR (VWS), AS PORTRAYED BY RECENT
CONTINUOUS CONSOLIDATION OF CONVECTIVE BANDING. THE INITIAL
INTENSITY OF 50 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON A
COMBINATION OF AGENCY FIXES AND OBJECTIVE ESTIMATES LISTED BELOW.
RECENT REGIONAL SURFACE OBSERVATIONS ARE ALSO SUPPORTING THE
POSITION AND INTENSITY OF THE SYSTEM.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: COMPETING IMPACTS OF A WEAK
NEAR-EQUATORIAL RIDGE (NER) TO THE NORTHEAST AND A BUILDING RIDGE
OVER AFRICA

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   KNES: T2.5 - 35 KTS
   CIMSS ADT: 53 KTS AT 260300Z
   CIMSS AIDT: 56 KTS AT 260500Z
   CIMSS D-MINT: 37 KTS AT 260328Z
   CIMSS D-PRINT: 43 KTS AT 260530Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 0-5 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE POLEWARD AND EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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 23S IS FORECAST TO TRACK
SOUTHEASTWARD, WHILE UNDER COMPETING STEERING ENVIRONMENT, WHICH
WILL INCREASE UNCERTAINTY AND MAY LEAD TO ERRATIC MOTION THROUGHOUT
THE FORECAST PERIOD. TOWARDS THE END OF THE TRACK FORECAST PERIOD, A 
BUILDING SUBTROPICAL RIDGE (STR) TO THE EAST WILL SLOW THE SYSTEM 
DOWN, WHILE THE RIDGE OVER AFRICA WILL ACT AS A BLOCKING PATTERN ON 
THE WESTERN SIDE. THEREFORE TRACK GUIDANCE AROUND TAU 120 AND BEYOND 
IS HIGHLY UNCERTAIN, WITH THE POTENTIAL FOR THE SYSTEM TO BECOME
QUASI-STATIONARY OR MOVE IN A LOOPING PATTERN. IN TERMS OF INTENSITY, 
THERE IS SOME POTENTIAL (25-35 PERCENT) FOR RAPID INTENSIFICATION (RI) 
AS INDICATED BY MULTIPLE IN-HOUSE RI AIDS. AT THE SAME TIME, 
DETERMINISTIC GUIDANCE OFFERS A MORE MODEST APPROACH, WITH THE MULTI-
MODEL CONSENSUS ESTIMATING A NEAR-RI INTENSIFICATION THROUGHOUT TAU 
36, FOLLOWED BY A VERY MINOR WEAKENING. SOME MODELS, LIKE GFS AND HAFS 
INDICATE A POTENTIAL FOR RE-INTENSIFICATION PAST TAU 96, FURTHER 
INCREASING UNCERTAINTY. ENVIRONMENTAL CONDITIONS AND POTENTIAL LAND 
INTERACTION WILL ALSO IMPACT INTENSITY FORECAST, BOTH BEING HEAVILY 
DEPENDENT ON THE ACTUAL TRACK AND THE DOMINATING STEERING PATTERN.

MODEL DISCUSSION: INITIAL NUMERICAL MODEL TRACK GUIDANCE IS IN A
SURPRISINGLY GOOD AGREEMENT, DESPITE UNCERTAINTY ASSOCIATED WITH
THE STEERING PATTERN, WITH NEARLY ALL MODELS PREDICTING A GENERALLY
SOUTHEASTWARD TRACK. ONE NOTEWORTHY OUTLIER IS GFS, WHICH TAKES THE
SYSTEM SLIGHTLY CLOSER TO MADAGASCAR BY TAU 48, FOLLOWED BY A COUNTER-
CLOCKWISE U-TURN. JTWC TRACK FORECAST IS LAID CLOSE TO THE MULTI-MODEL 
CONSENSUS, BUT IS LESS AGGRESSIVE IN REGARD TO THE SPEED OVER WATER 
TOWARDS THE END OF THE FORECAST PERIOD. CROSS-TRACK SPREAD AT TAU 48 
IS ONLY 50 NM, INCREASING CONFIDENCE OF THE SHORT TERM FORECAST. 
TAKING THE GFS GUIDANCE OUT OF THE EQUATION, THE CROSS-TRACK SPREAD AT 
TAU 120 INCREASES TO 135 NM, ONLY SLIGHTLY INCREASING UNCERTAINTY. 
HOWEVER, TAKING THE DRASTICALLY DIFFERENT DETERMINISTIC
GFS TRACK INTO CONSIDERATION, THE UNCERTAINTY INCREASES DRAMATICALLY. 
JTWC INTENSITY FORECAST IS THEREFORE ASSESSED WITH OVERALL MEDIUM 
CONFIDENCE THROUGHOUT THE FORECAST PERIOD, WITH NEARLY ALL MODELS 
FOLLOWING THE SAME INTENSIFICATION AND WEAKENING TRENDS. AT THE
SAME TIME THE INTENSITY GUIDANCE SPREAD AT TAU 36 IS AS HIGH AS 50
KTS, WITH HAFS AND COAMPS-TC ESTIMATES OF 55-60 KTS ON ONE END, AND
95-105 KTS PEAK COMING FROM THE RI AIDS.

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