WDXS31 PGTW 030300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 23S (HIDAYA)
WARNING NR 004//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 8.8S 43.3E
   INITIAL INTENSITY: 75 KTS
   GEOGRAPHIC REFERENCE: 653 NM NORTH-NORTHWEST OF ANTANANARIVO,
MADAGASCAR
   MOVEMENT PAST 6 HOURS: WESTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 26 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
CYCLONE (TC) 23S (HIDAYA) WITH A RAGGED EYE THAT APPEARED AROUND 
022200Z. THE SYSTEM HAS DRASTICALLY SYMMETRIZED OVER THE PAST 12 
HOURS AND HAS CONTINUED TO RAPIDLY INTENSIFY. A 030023Z 91 GHZ SSMIS 
SATELLITE MICROWAVE IMAGE ALSO SHOWED THAT THE SYSTEM IS VERY 
SYMMETRICAL WITH A WELL-DEFINED MICROWAVE EYE. THE CURRENT 
ENVIRONMENT HAS CONTINUED TO BE QUITE CONDUCIVE FOR FURTHER 
DEVELOPMENT WITH STRONG RADIAL OUTFLOW ALOFT, LOW (10-15 KTS) 
VERTICAL WIND SHEAR (VWS), AND WARM (29-30 C) SEA SURFACE 
TEMPERATURES. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE 
BASED ON THE RAGGED EYE SEEN IN THE ANIMATED EIR AND THE 
AFOREMENTIONED SSMIS MICROWAVE IMAGE. THE INITIAL INTENSITY OF 75 KTS 
IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON T4.5 DVORAK FIXES FROM 
MULTIPLE AGENCIES IN ADDITION TO THE OBJECTIVE INTENSITY ESTIMATES 
LISTED BELOW. A 021531Z RCM-3 SAR IMAGE REVEALED A VMAX OF 75 KTS 
ALSO AIDED IN THE ASSESSMENT OF THE INITIAL INTENSITY.

INITIAL WIND RADII BASIS: SAR DATA 

CURRENT STEERING MECHANISM: NORTHEASTERN PERIPHERY OF A SUBTROPICAL
RIDGE (STR) POSITIONED OVER SOUTHERN AFRICA. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   KNES: T4.5 - 77 KTS
   DEMS: T4.5 - 77 KTS
   FMEE: T4.5 - 77 KTS
   CIMSS ADT: 77 KTS AT 030000Z
   CIMSS AIDT: 83 KTS AT 030000Z
   CIMSS DPRINT: 72 KTS AT 030000Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG RADIAL

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: WITH THE SYSTEM UNDERGOING RAPID
INTENSIFICATION, THE PEAK FORECAST INTENSITY HAS BEEN INCREASED TO
90 KTS.

FORECAST DISCUSSION: TC 23S IS FORECAST TO BEGIN A
WEST-NORTHWESTWARD TRACK THROUGH TAU 36 AS THE SYSTEM CONTINUES TO
TRACK ALONG THE NORTHERN PERIPHERY OF THE STR TO THE SOUTHWEST.
AFTER TAU 36, THE SYSTEM IS FORECAST TO TRACK MORE NORTHWESTWARD AS
THE SYSTEM BEGINS TO WEAKEN AND TAKE ON THE MIDDLE TO LOWER-LEVEL 
STEERING INFLUENCE. REGARDING THE INTENSITY FORECAST, TC 23S IS 
FORECAST TO CONTINUE TO INTENSIFY TO A PEAK OF 90 KTS AT TAU 12 AND 
MAINTAIN 90 KTS THROUGH TAU 24. THIS IS DUE TO VWS VALUES REMAINING 
LOW AND THE SYSTEM CONTINUING TO FEND OFF DRY AIR ENTRAINMENT FROM 
AFRICA. AFTER TAU 24, THE SYSTEM IS FORECAST TO INITIATE A WEAKENING 
TREND AS LAND INTERACTION STARTS TO BECOME A FACTOR AND DRY AIR 
BEGINS TO ENTRAIN INTO THE SYSTEM FROM THE NORTH. TC 23S IS 
ANTICIPATED TO MAKE LANDFALL IN EASTERN AFRICA BETWEEN TAU 36 AND 48. 
ONCE THE SYSTEM MAKES LANDFALL, 23S WILL QUICKLY DEGRADE AND IS 
EXPECTED TO HAVE DISSIPATED NO LATER THAN TAU 72 AS IT TRACKS INTO 
TANZANIA. 

MODEL DISCUSSION: GLOBAL NUMERICAL MODEL GUIDANCE CONTINUES TO BE
IN POOR AGREEMENT WITH A 400 NM CROSS-TRACK SPREAD AT TAU 48.
ECMWF, GFS DETERMINISTIC, AND NAVGEM MAKE UP THE WESTWARD TRENDING
MEMBERS. GFS ENSEMBLE, GALWEM, AND UKMET TRACK THE SYSTEM 
NORTHWESTWARD AND THEN NEARLY STRAIGHT NORTHWARD AFTER TAU 24 
(WITHOUT MAKING LANDFALL). THE LATER GROUPING OF MODELS SHOWED A MUCH 
WEAKER SYSTEM IN GUIDANCE, SUGGESTING THE SYSTEMS STEERING IS 
AFFECTED MORE BY MIDDLE TO LOW-LEVEL FLOW. THE JTWC TRACK WAS PLACED 
WITH LOW CONFIDENCE, SOUTHWEST OF CONSENSUS FOLLOWING MORE CLOSELY TO 
THE WESTWARD TRENDING GUIDANCE AND DEEP-LAYER STEERING GIVEN THE 
RECENT RAPID INTENSIFICATION AND DEEP LAYERED SYSTEM. THE INTENSITY 
GUIDANCE IS ALSO IN POOR AGREEMENT, WITH A DISAGREEMENT BETWEEN THE 
MODELS THAT TRACK THE SYSTEM INLAND AND THE ONES THAT TURN NORTHWARD. 
RIPA IS INDICATING HIGH RAPID INTENSIFICATION PROBABILITY THROUGH TAU 
24. HAFS-A AND HWRF BOTH CALL FOR A GRADUAL WEAKENING TREND STARTING 
AT TAU 0. AS A RESULT, THE JTWC INTENSITY FORECAST IS PLACED WITH LOW 
CONFIDENCE, BELOW THE RI AIDS AND ABOVE THE MESOSCALE MODEL 
INDICATIONS.

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