WDXS31 PGTW 200300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 24S (IALY)       
WARNING NR 008//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 6.3S 44.5E
   INITIAL INTENSITY: 55 KTS
   GEOGRAPHIC REFERENCE: 776 NM NORTH-NORTHWEST OF ANTANANARIVO,
MADAGASCAR
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 22 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS RAPIDLY 
CYCLING DEEP CONVECTION AND WARMING CLOUD TOPS WITHIN AN INCREASINGLY 
ASYMMETRIC CONVECTIVE STRUCTURE. A 192238Z AMSR2 36 GHZ MICROWAVE 
IMAGE SHOWS A SMALL, DEFINED MICROWAVE EYE FEATURE ALONG THE NORTHERN 
PERIPHERY OF THE SYSTEM, WHICH SUPPORTS THE INITIAL POSITION WITH HIGH 
CONFIDENCE. DESPITE MODERATE, LIMITED RADIAL OUTFLOW, THE SYSTEM LACKS 
A STRONG OUTFLOW MECHANISM. ADDITIONALLY, SIGNIFICANT MID- TO UPPER-
LEVEL DRY AIR ENTRAINMENT IS EVIDENT, WHICH IS KEY TO THE RECENT 
WEAKENING TREND. THE INITIAL INTENSITY IS BASED ON THE SUBJECTIVE 
DVORAK CURRENT INTENSITY ESTIMATES OF 55 KNOTS.  

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) POSITIONED TO
THE WEST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   KNES: T3.5 - 55 KTS
   DEMS: T3.5 - 55 KTS
   CIMSS SATCON: 47 KTS AT 192229Z
   CIMSS ADT: 51 KTS AT 192100Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE RADIAL
   OTHER FACTORS: DRY AIR ENTRAINMENT

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   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 (TC) 24S IS TRACKING NORTH-
NORTHWESTWARD ALONG THE EASTERN PERIPHERY OF A NORTH-SOUTH ORIENTED 
SUBTROPICAL RIDGE AND IS FORECAST TO CONTINUE TRACKING NORTHWARD 
THROUGH THE FORECAST PERIOD. STEADY WEAKENING IS ANTICIPATED AS DRY 
AIR ADVECTS OFF TANZANIA INTO THE NORTHERN SEMICIRCLE OF THE SYSTEM, 
WITH DISSIPATION EXPECTED BY TAU 36.   

MODEL DISCUSSION: WITH THE EXCEPTION OF NAVGEM, THE SOLE OUTLIER,
DETERMINISTIC GUIDANCE REMAINS IN FAIR AGREEMENT, WITH A 60 TO 80
NM CROSS-TRACK SPREAD IN SOLUTIONS FROM TAU 24 TO TAU 36. RELIABLE
INTENSITY GUIDANCE SUPPORTS THE STEADY WEAKENING TREND WITH MEDIUM
CONFIDENCE. THE MAJORITY OF EPS AND GEFS PROBABILISTIC SOLUTIONS
ALSO INDICATE THE HIGHLY LIKELY DISSIPATION SCENARIO EQUATORWARD OF 4 
DEGREES SOUTH LATITUDE.

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