WDXS31 PGTW 140900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 12S (DUMAKO) WARNING 
NR 003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 16.5S 55.2E
   INITIAL INTENSITY: 50 KTS
   GEOGRAPHIC REFERENCE: 240 NM NORTH OF ST DENIS, LA REUNION
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 16 KTS
   SIGNIFICANT WAVE HEIGHT: 14 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A SMALL
SYSTEM WITH FLARING DEEP CENTRAL CONVECTION BUT VOID OF FEEDER RAIN
BANDS. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON
AN EXTRAPOLATION OF THE MICROWAVE EYE IN THE 140300Z GPM 37GHZ
IMAGE. THE INITIAL INTENSITY IS PLACED WITH HIGH CONFIDENCE BASED
ON AN OVERALL ASSESSMENT OF AGENCY AND AUTOMATED DVORAK ESTIMATES
(SEE BELOW) AND REFLECTS THE SUSTAINED 6-HR CONVECTIVE STRUCTURE
AND CONSISTENT WITH THE PRESENCE OF A MICROWAVE EYE. ANALYSIS
INDICATES A MARGINALLY UNFAVORABLE ENVIRONMENT WITH WARM ALONG-TRACK 
SST IN THE SOUTH INDIAN OCEAN OFFSET BY LIGHT TO MODERATE
VWS, WEAK RADIAL OUTFLOW ALOFT, AND LOW LEVEL DRY AIR INTRUSION.
THE CYCLONE IS TRACKING ALONG THE NORTHERN PERIPHERY OF THE STR TO
THE SOUTH.

INITIAL WIND RADII BASIS: PERSISTENCE 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   CIMSS SATCON: 48 KTS AT 140317Z
   CIMSS ADT: 53 KTS AT 140515Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY
UNFAVORABLE
   VWS: 15-20 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: WEAK RADIAL

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TC DUMAKO WILL CONTINUE ON ITS CURRENT TRACK
UNDER THE STEERING INFLUENCE OF THE STR TO THE SOUTH. AFTER TAU 12,
A SECONDARY STR TRANSITING FROM THE SOUTHWEST WILL ASSUME STEERING
AND DRIVE THE SYSTEM ON A MORE WEST-NORTHWESTWARD TRAJECTORY,
MAKING LANDFALL OVER NORTHEASTERN MADAGASCAR AROUND TAU 30. THE
MARGINAL ENVIRONMENT WILL PERSIST ALONG THE FORECAST TRACK AND
GRADUALLY ERODE THE SYSTEM. THIS, PLUS THE FRICTIONAL EFFECTS OF
LAND INTERACTION AFTER LANDFALL WILL LEAD TO DISSIPATION OVER LAND
BY TAU 48. THERE IS A POSSIBILITY THAT TC 12S WILL DISSIPATE SOONER
PRIOR TO LANDFALL.   

MODEL DISCUSSION: NUMERICAL MODELS ARE IN OVERALL GOOD AGREEMENT
WITH A GRADUAL SPREAD TO 116NM BY TAU 48. HOWEVER, DUE TO THE
POSSIBLE EARLY DISSIPATION, THERE IS ONLY MEDIUM CONFIDENCE IN THE
JTWC TRACK AND INTENSITY FORECASTS. 

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