WDXS31 PGTW 011500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 23S (TWENTY-THREE) 
WARNING NR 001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 8.6S 45.1E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 634 NM NORTH-NORTHWEST OF ANTANANARIVO,
                         MADAGASCAR
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 02 KTS
   SIGNIFICANT WAVE HEIGHT: 14 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
AS INDICATED IN ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI),
TROPICAL CYCLONE (TC) 23S HAS SLOWLY CONSOLIDATED, WITH IMPROVED
DEEP CONVECTIVE BANDING WRAPPING INTO A PARTIALLY-EXPOSED, DEFINED
LOW-LEVEL CIRCULATION CENTER (LLCC). A 011023Z AMSR2 89 GHZ
MICROWAVE IMAGE DEPICTS FRAGMENTED DEEP CONVECTIVE BANDING OVER THE
SOUTHERN SEMICIRCLE WRAPPING TIGHTLY INTO A DEFINED LLCC, WHICH
SUPPORTS THE INITIAL POSITION WITH HIGH CONFIDENCE. THE AMSR2 37
GHZ COLOR COMPOSITE MICROWAVE IMAGE APPEARS TO SHOW A WEAK,
FORMATIVE MICROWAVE EYE FEATURE DISPLACED SLIGHTLY (12 NM) TO THE
SOUTHEAST OF THE UPPER-LEVEL CIRCULATION CENTER, INDICATIVE OF THE
IMPROVED OVERALL CONVECTIVE STRUCTURE. ANIMATED WATER VAPOR RGB
IMAGERY REVEALS A DEEP MOIST ENVELOPE, WITH RADIAL OUTFLOW AND
ENHANCED POLEWARD OUTFLOW. THE INITIAL INTENSITY OF 35 KTS IS
ASSESSED WITH HIGH CONFIDENCE BASED ON CONCURRENT SUBJECTIVE
DVORAK ESTIMATES OF T2.5 (35 KNOTS) FROM ALL AGENCIES.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: LOW- TO MID-LEVEL SUBTROPICAL RIDGE
(STR) CENTERED TO THE SOUTHEAST NEAR LA REUNION, WITH A RIDGE
EXTENDING WESTWARD OVER THE MOZAMBIQUE CHANNEL. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   KNES: T2.5 - 35 KTS
   FMEE: T2.5 - 35 KTS

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

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING
MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY.

FORECAST DISCUSSION: TC 23S IS FORECAST TO TRACK SLOWLY WESTWARD TO
WEST-SOUTHWESTWARD ALONG THE NORTHWESTERN TO NORTHERN PERIPHERY OF
THE STR THROUGH TAU 36. ALTHOUGH THE SYSTEM IS SLOWLY CONSOLIDATING, 
FAVORABLE ENVIRONMENTAL CONDITIONS WILL ALLOW THE SYSTEM TO INTENSIFY 
MORE RAPIDLY OVER THE NEXT 24-36 HOURS TO A PEAK INTENSITY OF 50 
KNOTS. AFTER TAU 36, THE SYSTEM WILL TRANSITION TO THE STEERING 
INFLUENCE OF A BUILDING STR OVER SOUTHERN AFRICA, WHICH WILL TURN THE 
SYSTEM ONTO A WEST-NORTHWESTWARD TO NORTHWESTWARD TRACK THROUGH TAU 
96. ENVIRONMENTAL CONDITIONS WILL GRADUALLY DEGRADE, WITH DRY AIR 
ENTRAINMENT AND INCREASING VERTICAL WIND SHEAR LEADING TO A STEADY 
WEAKENING TREND. ADDITIONALLY, INTERACTION WITH LAND WILL CONTRIBUTE 
TO MORE SIGNIFICANT WEAKENING AFTER TAU 72, WITH DISSIPATION EXPECTED 
NO LATER THAN TAU 96.      
 
MODEL DISCUSSION: GLOBAL DETERMINISTIC MODEL GUIDANCE SHOWS A LARGE
SPREAD IN SOLUTIONS WITH THE MORE RELIABLE MODELS (ECMWF, ECMWF
ENSEMBLE MEAN AND GFS) SUPPORTING THE JTWC TRACK PHILOSOPHY. THE
GALWEM AND NAVGEM TRACKERS DEPICT AN UNLIKELY NORTHWARD TRACK. THE
BULK (ROUGHLY 80 PERCENT) OF THE ECMWF ENSEMBLE SOLUTIONS SUPPORT A 
WESTWARD TO WEST-NORTHWESTWARD TRACK. THE 010000Z GFS ENSEMBLE
INDICATES A MORE NORTHWESTWARD TO NORTHWARD TRACK ALONG THE EASTERN
COAST OF TANZANIA AND KENYA. THE 010000Z COAMPS-TC INTENSITY ENSEMBLE
INDICATES HIGH PROBABILITIES (80 TO 100 PERCENT) OF MODERATE 
INTENSIFICATION OVER THE NEXT DAY WITH A LOW PROBABILITY (30 TO 40
PERCENT) OF RAPID INTENSIFICATION. THE JTWC INTENSITY FORECAST IS
ASSESSED WITH MEDIUM CONFIDENCE AND IS SUPPORTED BY THE BULK OF THE
RELIABLE INTENSITY GUIDANCE TO INCLUDE HAFS-A, DECAY SHIPS AND THE
JTWC INTENSITY CONSENSUS (ICNW).            

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