WDXS31 PGTW 181500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 24S (IALY) WARNING NR 
005//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 7.8S 47.9E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 668 NM NORTH OF ANTANANARIVO, MADAGASCAR
   MOVEMENT PAST 6 HOURS: WESTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS THE SYSTEM
HAS BECOME MORE COMPACT AS CENTRAL CONVECTION DEEPENED AND OBSCURED
THE PREVIOUSLY PARTIALLY-EXPOSED LOW LEVEL CIRCULATION (LLC). THE
INITIAL POSITION IS PLACED WITH LOW CONFIDENCE USING LOW CLOUD
TRACING INTO THE OBSCURED LLC AND EXTRAPOLATION FROM THE RECENT
STORM MOTION. THE INITIAL INTENSITY IS PLACED WITH MEDIUM CONFIDENCE 
BASED ON THE HIGH END OF AGENCY AND AUTOMATED DVORAK ESTIMATES AND 
REFLECTS THE 6-HR CONVECTIVE IMPROVEMENT. ANALYSIS INDICATES A 
MARGINALLY FAVORABLE ENVIRONMENT WITH MODERATE POLEWARD OUTFLOW AND 
WARM SST OFFSET BY MODERATE VWS AND COLD DRY AIR INTRUSION AT THE LOW 
LEVELS.

INITIAL WIND RADII BASIS: PERSISTENCE.

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE
SOUTH-SOUTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   KNES: T3.0 - 45 KTS
   DEMS: T2.5 - 35 KTS
   FMEE: T3.5 - 55 KTS
   CIMSS SATCON: 41 KTS AT 180930Z
   CIMSS ADT: 53 KTS AT 181130Z
   CIMSS AIDT: 50 KTS AT 181130Z
   CIMSS DPRINT: 47 KTS AT 181200Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 20-25 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: LOW
   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: TC IALY WILL TACK MORE NORTHWESTWARD AS THE
STR TO THE WEST ASSUMES STEERING. VWS AND THE COLD DRY AIR
INTRUSION ARE EXPECTED TO INCREASE LEADING TO A GRADUAL DECAY AND
EVENTUAL DISSIPATION BY TAU 48. 

MODEL DISCUSSION: NUMERICAL MODELS ARE IN OVERALL GOOD AGREEMENT UP
TO TAU 48 WITH NAVGEM AS THE SOLE LEFT OUTLIER LENDING MEDIUM
CONFIDENCE TO THE JTWC TRACK FORECAST THAT IS LAID JUST TO THE
RIGHT OF CONSENSUS TO OFFSET NAVGEM. 

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