WDXS32 PGTW 272100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 14S (ENALA) WARNING NR 012// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 28.6S 67.7E INITIAL INTENSITY: 45 KTS GEOGRAPHIC REFERENCE: 763 NM SOUTHEAST OF PORT LOUIS, MAURITIUS MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 05 KTS SIGNIFICANT WAVE HEIGHT: 16 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: RECENT PHASE CLASSIFICATION ANALYZES SUGGEST TC 14S (ENALA) IS A HYBRID SYSTEM, WITH CHARACTERISTICS OF BOTH A TROPICAL CYCLONE AND A SUBTROPICAL LOW. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A RELATIVELY BROAD LOW LEVEL CIRCULATION (LLC) WITH LOW-LEVEL SPIRAL BANDS WRAPPING INTO A BROAD CENTER, AND FLARING DEEP CONVECTION CONFINED MOSTLY TO THE SOUTHERN SIDE OF THE CIRCULATION. RECENT SCATTEROMETER AND A RADARSAT CONSTELLATION MISSION (RCM) SYNTHETIC APERTURE RADAR (SAR) PASS PROVIDED HIGH CONFIDENCE TO THE INITIAL POSITION AND INTENSITY. THE SAR SHOWED MAXIMUM WINDS MOSTLY IN THE 40-45 KNOT RANGE WITH A FEW ISOLATED POCKETS OF WINDS APPROACHING 50 KNOTS, WHICH IS QUITE A BIT HIGHER THAN THE MAJORITY OF THE DVORAK-BASED INTENSITY ESTIMATES. THE SYSTEM IS MOVING NORTHEASTWARD NOW, ALONG THE EAST SIDE OF A LOW TO MID-LEVEL SUBTROPICAL RIDGE (STR) TO THE EAST, HAVING COMPLETED A COUNTER-CLOCKWISE LOOP OVER THE PAST DAY. ENVIRONMENTAL CONDITIONS ARE MARGINAL, WITH LOW TO MODERATE (15-20 KTS) VWS, WEAK EASTWARD OUTFLOW AND RELATIVELY COOL SSTS. INITIAL WIND RADII BASIS: SCATTEROMETER AND SAR DATA CURRENT STEERING MECHANISM: EASTERN PERIPHERY OF A LOW TO MID-LEVEL STR TO THE WEST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T2.5 - 35 KTS KNES: T2.5 - 35 KTS CIMSS SATCON: 41 KTS AT 271633Z CIMSS ADT: 35 KTS AT 271800Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL VWS: 15-20 KTS SST: 25-26 CELSIUS OUTFLOW: WEAK EASTWARD ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: HIGH INITIAL WIND RADII: HIGH 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THE TRANSITION PHASE OF THE FORECAST HAS BEEN CHANGED TO SUBTROPICAL. OTHERWISE, THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: OVER THE PAST 12 HOURS, TC 14S HAS TURNED NORTHEASTWARD AND PICKED UP SPEED, AS THE LOW TO MID-LEVEL STEERING RIDGE TO THE WEST HAS STRENGTHENED. OVER THE NEXT DAY OR SO, THE RIDGE WILL SLIDE EASTWARD TO THE SOUTH OF THE SYSTEM, AND BY ABOUT TAU 48 WILL TAKE UP POSITION TO THE EAST OF TC 14S. AS THE RIDGE MOVES BY TO THE SOUTH, TC 14S WILL CONTINUE INTO ANOTHER COUNTER-CLOCKWISE LOOP, EVENTUALLY ENDING UP NOT FAR FROM ITS CURRENT POSITION, AND TRACKING TOWARDS THE SOUTH BY THE END OF THE FORECAST PERIOD. THE SYSTEM CURRENTLY LIES UNDER A 200MB TROUGH WHICH IS USHERING IN AN INFLUX OF MID-LEVEL DRY AIR FROM THE WEST, AND INDUCING SOME CONVERGENT FLOW ALOFT. WHILE THE TROUGH MOVES OUT TO THE EAST OVER THE NEXT 12 HOURS, THE DRY AIR IS EXPECTED TO REMAIN FIRMLY IN PLACE, EFFECTIVELY SMOTHERING THE SYSTEM AND PRECLUDING CONVECTIVE CONSOLIDATION. AS THE SYSTEM MOVES NORTH, IT WILL FLIRT WITH THE 26C ISOTHERM, BUT THE COMBINATION OF THE DRY AIR AND INCREASED SHEAR ASSOCIATED WITH ANOTHER UPPER-LEVEL TROUGH PUSHING THROUGH AROUND TAU 48, WILL SERVE TO STEADILY, ALBEIT SLOWLY, WEAKEN THE SYSTEM WHILE SIMULTANEOUSLY SUPPORTING SUBTROPICAL TRANSITION (STT). THE JURY IS STILL OUT ON WHETHER THE SYSTEM WILL DISSIPATE OR COMPLETE SUBTROPICAL TRANSITION FIRST, AND THE FORECAST CALLS FOR THE TWO TO OCCUR AT THE SAME TIME, NO LATER THAN TAU 72, THOUGH IT REMAINS POSSIBLE THE SYSTEM COULD COMPLETE STT AS EARLY AS TAU 48. MODEL DISCUSSION: ALL CONSENSUS MODEL MEMBERS CONCUR ON THE OVERALL SCENARIO, WITH THE TRACKERS SHOWING A COUNTER-CLOCKWISE LOOP THROUGH TAU 72, WITH ONLY A MODERATE AMOUNT OF SPREAD. THE JTWC FORECAST LIES ON THE INSIDE OF THE LOOP, CLOSEST TO THE GFS SOLUTION. CONFIDENCE IS LOW HOWEVER, DUE TO THE UNCERTAINTIES ASSOCIATED WITH LOOPING TRACKS AND THE OVERALL WEAK STEERING INFLUENCES. INTENSITY GUIDANCE IS MIXED, WITH THE COAMPS-TC (BOTH GFS AND NAVGEM VERSIONS) SHOWING NEAR-TERM INTENSIFICATION, WHILE THE HWRF AND DECAY-SHIPS SHOW SIGNIFICANT WEAKENING IN THE FIRST 24 HOURS, THOUGH THIS COULD BE AN ARTIFACT OF RECENT UPWARD REANALYSIS OF THE INITIAL INTENSITIES. OVERALL THE JTWC FORECAST LIES NEAR THE CONSENSUS MEAN, SHOWING A STEADY BUT SLOW WEAKENING THROUGH THE END OF THE FORECAST, WITH LOW CONFIDENCE. FORECAST CONFIDENCE: TRACK 0 - 72 HR: LOW INTENSITY 0 - 72 HR: LOW// NNNN