WDXS31 PGTW 190300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 13S (EMNATI) WARNING NR 006// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 16.0S 59.5E INITIAL INTENSITY: 70 KTS GEOGRAPHIC REFERENCE: 276 NM NORTH-NORTHEAST OF PORT LOUIS, MAURITIUS MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 11 KTS SIGNIFICANT WAVE HEIGHT: 24 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS THE CENTRAL CONVECTION HAS BECOME BETTER ORGANIZED OVER THE ASSESSED LOW LEVEL CIRCULATION CENTER (LLCC) WITHIN THE PAST 12 HOURS. A 190020Z SSMIS 91 GHZ IMAGE SHOWS FRAGMENTED BANDING WITH ASSOCIATED DEEP CONVECTION IN THE WESTERN PERIPHERY WRAPPING AROUND A WELL-DEFINED MICROWAVE EYE. INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE AFOREMENTIONED MICROWAVE IMAGERY. THE INITIAL INTENSITY OF 70 KTS IS ASSESSED WITH MEDIUM CONFIDENCE HEDGED SLIGHTLY HIGHER THAN THE ADT ESTIMATE OF 65 KTS AND MULTI- AGENCY DVORAK ESTIMATES OF 4.0, AND IS MORE ALIGNED WITH THE SATCON ESTIMATE OF 71 KTS. INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: DEEP LAYER SUBTROPICAL RIDGE (STR) TO THE SOUTHEAST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T4.0 - 65 KTS FMEE: T4.0 - 65 KTS FIMP: T4.0 - 65 KTS CIMSS SATCON: 71 KTS AT 182110Z CIMSS ADT: 63 KTS AT 190015Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 5-10 KTS SST: 28-29 CELSIUS OUTFLOW: MODERATE WESTWARD AND POLEWARD ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: MEDIUM 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING, HOWEVER THERE IS A POTENTIAL FOR AN ALTERNATE SCENARIO AS DESCRIBED IN THE MODEL DISCUSSION. FORECAST DISCUSSION: TC EMNATI WILL CONTINUE ITS TRACK TO THE SOUTHWEST OVER THE NEXT 36 HOURS WHILE STEADILY INCREASING IN INTENSITY TO 90 KTS AT THIS TIME. AFTER TAU 36, THE SYSTEM WILL TAKE A SLIGHT JOG EQUATORWARD AS THE STR TO THE SOUTHEAST WILL BUILD. AT THIS POINT, TC EMNATI WILL REACH ITS MAX INTENSITY OF 95 KTS. AFTERWARDS, AS THE SYSTEM APPROACHES THE EAST COAST OF MADAGASCAR, IT WILL BEGIN TO SHOW SIGNS OF WEAKENING IN INTENSITY AS THE OCEAN HEAT CONTENT WILL BEGIN TO FALL DUE TO UPWELLING THAT WAS INITIALLY KICKED-OFF WITH THE PASSING OF TC 08S AND TC 12S. DUE TO THIS UPWELLING, TC EMNATI WILL DECREASE IN INTENSITY 85 KTS BY TAU 72, ROUGHLY 6 HOURS BEFORE LANDFALL. THE SYSTEM WILL CONTINUE TO DECAY AS IT UNDERGOES TERRAIN INTERACTION BY TAU 96. BY TAU 120, TC EMNATI IS EXPECTED TO REEMERGE OVER THE SOUTHERN PORTION OF THE MOZAMBIQUE CHANNEL AT 30 KTS. MODEL DISCUSSION: FORECAST TRACK GUIDANCE IS IN GREAT AGREEMENT THROUGH TAU 12. HOWEVER AFTER TAU 12 THEY BEGIN TO SPLIT EXPONENTIALLY. THERE IS A 48 NM SPREAD AT TAU 24, SPREADING TO A 480 NM SPREAD BY TAU 120. ECWMF AND AFUM LAY THERE TRACKS MORE EQUATORWARD; GFS IS MORE POLEWARD, WITH NAVGEM BEING THE OUTLIER AND TURNING THE STORM SOUTH-SOUTHWEST AFTER TAU 72. THE JTWC TRACK IS PLACED WITH MEDIUM CONFIDENCE THROUGH TAU 72, SLIGHTLY RIGHT OF CONSENSUS GUIDANCE. AFTER TAU 72, TRACK CONFIDENCE IS LOW DUE TO THE SPORADIC NATURE OF THE MODEL GUIDANCE. IT SHOULD BE NOTED THAT THE LAST THREE GFS DETERMINISTIC AND ENSEMBLE RUNS SHOW A MORE POLEWARD TRACK AFTER TAU 72. INTENSITY GUIDANCE IS IN FAIR AGREEMENT THROUGH TAU 72. THE FORECAST INTENSITY IS PLACED SLIGHTLY HIGHER THAN CONSENSUS, THEN BELOW CONSENSUS AFTER TAU 72 TO ACCOUNT FOR THE AFOREMENTIONED UPWELLING EAST OF MADAGASCAR. FORECAST CONFIDENCE: TRACK 0 - 72 HR: MEDIUM TRACK 72-120 HR: LOW INTENSITY 0 - 72 HR: MEDIUM INTENSITY 72-120 HR: LOW// NNNN