WDXS31 PGTW 230900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 13S (EMNATI) WARNING NR 
015//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 23.6S 46.3E
   INITIAL INTENSITY: 60 KTS
   GEOGRAPHIC REFERENCE: 290 NM SOUTH-SOUTHWEST OF ANTANANARIVO,
MADAGASCAR
   MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 18 KTS
   SIGNIFICANT WAVE HEIGHT: 00 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS THE SYSTEM HAS
MADE LANDFALL OVER SOUTH CENTRAL MADAGASCAR. THE CENTRAL CONVECTIVE
TOPS HAVE SIGNIFICANTLY WARMED AND COLLAPSED AS IT ENCOUNTERED THE
RUGGED TERRAIN. HOWEVER, REMNANTS OF THE EYEWALL REMAIN VISIBLE.
THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE
REMNANT EYEWALL THAT LINED UP WELL WITH A PARTLY OBSCURE LOW LEVEL
MICROWAVE EYE FEATURE IN THE 230302Z SSMIS 91GHZ IMAGE. THE INITIAL
INTENSITY IS EXTRAPOLATED FROM DVORAK ESTIMATES PRIOR TO LANDFALL
AND REFLECTS THE 6-HR DECAY. ANALYSIS INDICATES AN UNFAVORABLE
ENVIRONMENT WITH LOW VWS AND MODERATE RADIAL OUTFLOW OFFSET BY
FRICTIONAL EFFECTS OF THE RUGGED TERRAIN. TC 13S IS TRACKING ALONG
THE NORTHWESTERN PERIPHERY OF THE STR TO THE SOUTHEAST.

INITIAL WIND RADII BASIS: EXTRAPOLATION FROM PREVIOUS WIND RADII.

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: NO CURRENT ESTIMATE

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 10-15 KTS
   SST: OVER LAND
   OUTFLOW: MODERATE RADIAL

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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 13S WILL CONTINUE ON ITS CURRENT
SOUTHWESTWARD TRACK UNDER THE STEERING INFLUENCE OF THE STR AND
EXIT INTO THE MOZAMBIQUE CHANNEL JUST BEFORE TAU 12. AFTER TAU 24, IT 
WILL TRACK MORE SOUTHWARD AS IT ROUNDS THE WESTERN EDGE OF THE STR. 
INTERACTION WITH THE RUGGED TERRAIN, THEN THE COOLER (24C) SST AND 
STRONG (30KT+) VWS, OFFSET BY STRONG POLEWARD OUTFLOW IN THE 
MOZAMBIQUE CHANNEL WILL RESULT IN GRADUAL DECAY - DOWN TO 45KTS BY TAU 
48. CONCURRENTLY BY TAU 36, TC 13S WILL BEGIN SUBTROPICAL TRANSITION 
AND BY TAU 48, WILL TRANSFORM INTO A SUBTROPICAL SYSTEM WITH AN 
EXPANDING WIND FIELD.   

MODEL DISCUSSION: NUMERICAL MODELS ARE GENERALLY IN GOOD AGREEMENT
WITH A GRADUAL SPREAD TO 138 NM BY TAU 48. HOWEVER, DUE TO THE
UNCERTAINTY OF A LAND PASSAGE, THERE IS OVERALL MEDIUM CONFIDENCE IN 
THE JTWC TRACK AND INTENSITY FORECASTS.  


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