WDXS31 PGTW 020300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 23S (HIDAYA) 
WARNING NR 002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 9.1S 44.6E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 612 NM NORTH-NORTHWEST OF ANTANANARIVO,
MADAGASCAR
   MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
CYCLONE (TC) 23S WITH A PARTIALLY EXPOSED LOW-LEVEL CIRCULATION
CENTER (LLCC) AND DEEP CONVECTIVE BANDING BEGINNING TO WRAP INTO
THE SYSTEM ALONG THE SOUTHERN SEMICIRCLE OF THE SYSTEM. A 020037Z
SSMIS 91 GHZ MICROWAVE IMAGE REVEALS THE IMPROVED BANDING IN THE
SOUTHERN AND WESTERN PERIPHERIES. ENVIRONMENTAL ANALYSIS INDICATES
THAT THE CURRENT ENVIRONMENT IS FAVORABLE, CHARACTERIZED BY
MODERATE RADIAL OUTFLOW ALOFT, LOW (5-10 KTS) VERTICAL WIND SHEAR
(VWS), AND WARM (29-30 C) SEA SURFACE TEMPERATURES. THE INITIAL
POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON THE ANIMATED EIR
AND PREVIOUSLY MENTIONED SSMIS MICROWAVE IMAGE. THE INITIAL
INTENSITY OF 35 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE
OBJECTIVE AND SUBJECTIVE INTENSITY ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF AN EXTENSION OF A
SUBTROPICAL RIDGE (STR) POSITIONED TO THE EAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   KNES: T2.5 - 35 KTS
   FMEE: T3.0 - 45 KTS
   CIMSS SATCON: 36 KTS AT 012200Z
   CIMSS ADT: 34 KTS AT 020000Z
   CIMSS AIDT: 36 KTS AT 020000Z
   CIMSS DPRINT: 34 KTS AT 020000Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE RADIAL

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TC 23S IS FORECAST TO BEGIN A WESTWARD TRACK
THROUGH TAU 12 AS THE STEERING INFLUENCE SHIFTS TO A DEEP-LAYERED
STR POSITIONED OVER SOUTHERN AFRICA. AFTER TAU 12, THE SYSTEM IS
FORECAST TO TAKE ON A NORTHWESTWARD TRACK ALONG THE NORTHEASTERN
PERIPHERY OF THE STR THROUGH THE REMAINDER OF THE FORECAST PERIOD.
REGARDING THE INTENSITY FORECAST, TC 23S IS FORECAST TO INTENSIFY
TO A PEAK INTENSITY OF 50 KTS AROUND TAU 24 AS THE ENVIRONMENT
REMAINS CONDUCIVE WITH LOW VWS AND HIGH MOISTURE CONTENT. THE
SYSTEM IS THEN FORECAST TO RETAIN 50 KTS THROUGH TAU 36 BEFORE
STARTING A WEAKENING TREND. AS VWS VALUES BEGIN TO INCREASE TO
AROUND 20 KTS AND DRY AIR BEGINS TO ENTRAIN INTO THE SYSTEM, TC 23S 
WILL QUICKLY DEGRADE. DISSIPATION IS FORECAST TO OCCUR NO
LATER THAN TAU 72, BEFORE THE SYSTEM MAKES LANDFALL.

MODEL DISCUSSION: GLOBAL NUMERICAL MODEL GUIDANCE IS IN RELATIVELY
POOR AGREEMENT THROUGHOUT THE FORECAST PERIOD WITH A 130 NM
CROSS-TRACK SPREAD AT TAU 24, WHICH INCREASES TO 335 NM AT TAU 72.
VORTEX TRACKERS VARY WITH SOME MEMBERS (UKMET, GALWEM, AND GFS
ENSEMBLE) TAKING A NORTH-NORTHWESTWARD TRACK WHILE OTHER MEMBERS
(ECMWF, GFS DETERMINITSIC, AND NAVGEM) TAKE A MORE WESTWARD TO
WEST-NORTHWESTWARD TRACK. THE JTWC TRACK IS PLACED SOUTHEAST OF
CONSENSUS, FOLLOWING MORE CLOSELY THE WESTWARD TRENDING MEMBERS.
INTENSITY GUIDANCE IS IN BETTER AGREEMENT WITH HAFS-A AND HWARF
BOTH SUGGESTING A PEAK INTENSITY OF 55-60 KTS AT TAU 24 BEFORE
STARTING THE WEAKENING TREND. COAMPS-TC SUGGESTS A PEAK INTENSITY
OF JUST 35-40 KTS AROUND TAU 12-18. THE JTWC INTENSITY FORECAST IS
PLACED WITH MEDIUM CONFIDENCE, JUST BELOW THE MORE AGGRESSIVE
GROUPING. 

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