WDXS31 PGTW 021500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 23S (HIDAYA) WARNING NR 003// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 8.7S 44.1E INITIAL INTENSITY: 50 KTS GEOGRAPHIC REFERENCE: 308 NM EAST-SOUTHEAST OF DAR ES SALAAM, TANZANIA MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 02 KTS SIGNIFICANT WAVE HEIGHT: 17 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: TROPICAL CYCLONE (TC) 23S (HIDAYA) HAS RAPIDLY CONSOLIDATED AND INTENSIFIED OVER THE PAST SIX TO TWELVE HOURS, UNDER SUPPORTIVE ENVIRONMENTAL CONDITIONS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A CONSOLIDATED LOW LEVEL CIRCULATION CENTER (LLCC), AND A BANDING EYE FEATURE, WITH DEEP CONVECTION ORGANIZED INTO VORTICAL HOT TOWERS (VHTS) FIRING PRIMARILY IN THE WESTERN HEMISPHERE OF THE NASCENT EYE FEATURE. A 021108Z AMSR2 37GHZ MICROWAVE IMAGE SHOWED A VERY WELL-DEFINED, 25NM WIDE MICROWAVE FEATURE SURROUNDED BY STRONG LOW-LEVEL CONVECTION. THE COLOR ENHANCED 37GHZ IMAGE SHOWED A CYAN RING, AS DID AN EARLIER 020658Z COWVR IMAGE, SUGGESTIVE OF RAPID DEVELOPMENT. THE LOW-LEVEL MICROWAVE EYE WAS OFFSET SLIGHTLY TO THE WEST OF A MUCH BROADER AND WEAKER 89GHZ CENTER FEATURE, INDICATIVE OF SOME WEST-NORTHWESTERLY MID-LEVEL SHEAR IMPACTING THE SYSTEM. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE AMSR2 37GHZ MICROWAVE EYE FEATURE. THE INITIAL INTENSITY WAS PLACED BETWEEN THE AGENCY DVORAK FIXES OF T3.0 AND T3.5 AND WELL ABOVE THE OBJECTIVE ESTIMATES, WHICH WERE ALL BELOW 50 KNOTS. THE ENVIRONMENT IS FAVORABLE FOR ADDITIONAL DEVELOPMENT, CHARACTERIZED BY LOW DEEP-LAYER SHEAR, STRONG POLEWARD, DIVERGENT OUTFLOW ALOFT AND ZESTY SSTS. INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: THE SYSTEM IS CURRENTLY IN A RELATIVELY WEAK STEERING ENVIRONMENT, CAUGHT BETWEEN A STR FAR TO THE EAST AND A DEVELOPING STR OVER SOUTH AFRICA. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T3.5 - 55 KTS KNES: T3.0 - 45 KTS DEMS: T3.0 - 45 KTS FMEE: T3.5 - 55 KTS CIMSS ADT: 34 KTS AT 021200Z CIMSS DPRINT: 50 KTS AT 021200Z CIMSS DMINT: 39 KTS AT 021109Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 0-5 KTS SST: 29-30 CELSIUS OUTFLOW: STRONG POLEWARD ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: LOW 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: WITH THE SYSTEM UNDERGOING RAPID INTENSIFICATION, THE PEAK FORECAST INTENSITY HAS BEEN INCREASED BY 15 KNOTS. FORECAST DISCUSSION: AS DISCUSSED ABOVE, TC 23S HAS EXPERIENCED A PERIOD OF RAPID CONSOLIDATION AND INTENSIFICATION OVER THE PAST SIX TO TWELVE HOURS AS IT HAS MEANDERED ON AN ERRATIC TRACK. PREVIOUSLY HEADING SOUTHWEST, THE SYSTEM TURNED SHARPLY NORTHWARD AFTER 020000Z, AND HAS NOW BEEN TRACKING SLOWLY TOWARDS THE NORTH-NORTHWEST IN A GENERALLY WEAK STEERING ENVIRONMENT. OVER THE NEXT 12 TO 24 HOURS, THE STR BUILDING OVER SOUTH AFRICA WILL MOVE TOWARDS THE NORTHEAST AND CONTINUE TO STRENGTHEN, AND TAKE OVER AS THE PREDOMINANT STEERING INFLUENCE FOR TC 23S. IN RESPONSE, TC 23S WILL TURN TO A MORE WEST-NORTHWESTWARD TRACK AND SPEED UP A NOTCH AS THE GRADIENT TIGHTENS. BY THE END OF THE FORECAST, AS THE SYSTEM WEAKENS, IT WILL COME UNDER THE INFLUENCE OF THE LOWER-LEVEL FLOW PATTERN, WHICH WILL DRIVE IT MORE NORTHWARD, ROUGHLY PARALLEL TO THE COAST OF TANZANIA. THE SYSTEM IS EXPECTED TO BRUSH THE COAST OF TANZANIA, WITH THE CURRENT FORECAST CALLING FOR A BRIEF LANDFALL JUST SOUTH OF DAR ES SALAAM. IN THE NEAR-TERM, IF THE VHTS CAN SUCCESSFULLY ENCLOSE THE ENTIRE LLCC, THE SYSTEM IS LIKELY TO RAPIDLY INTENSIFY. THE ONLY HINDRANCE IS THE TIME IT WILL TAKE FOR THE AXISYMMETRIZATION PROCESS TO COMPLETE. TIME IS THE LIMITING FACTOR, WITH ONLY ABOUT 24-36 HOURS AVAILABLE BEFORE HIGH WIND SHEAR AND DRY AIR WILL CONSPIRE TO TEAR THE SYSTEM APART. THE PEAK INTENSITY IS SET AT 65 KNOTS, BUT THERE IS A POSSIBILITY OF A STRONGER PEAK IF THE SYMMETRIZATION PROCESS COMPLETES QUICKLY. AFTER TAU 24, SHEAR BEGINS TO INCREASE, REALLY KICKING IN AFTER TAU 36, AT WHICH POINT THE SYSTEM RAPIDLY WEAKENS. DISSIPATION BELOW WARNING CRITERIA IS EXPECTED BY TAU 72, AS THE COMBINATION OF HIGH SHEAR, DRY MID-LEVEL AIR AND TERRAIN INTERACTION WILL TEAR THE SYSTEM APART. MODEL DISCUSSION: DETERMINISTIC AND ENSEMBLE GUIDANCE IS IN POOR AGREEMENT, AND CONTINUES TO DISPLAY A WIDE SPREAD IN POTENTIAL TRACK SOLUTIONS. THE ECMWF (00Z RUN) AND THE GFS ARE THE MOST SOUTHERN OF THE CONSENSUS MEMBERS, TAKING THE SYSTEM INLAND WELL SOUTH OF DAR ES SALAAM. THE ECMWF (06Z INTERMEDIATE RUN) IS A BIT FURTHER NORTH AND IS CONSISTENT WITH THE JTWC FORECAST TRACK. THE REMAINDER OF THE CONSENSUS MEMBERS ARE ALL NORTH AND EAST OF THE JTWC FORECAST, SPREAD OUT ALL THE WAY TO THE UKMET TRACKER WHICH EAST OF 42E. THE JTWC FORECAST IS WELL WEST OF THE CONSENSUS MEAN, WHICH IS BEING PULLED EAST BY THE UKMENT, GALWEM AND UKMET ENSEMBLE MEAN WHICH ALL LIE EAST OF 41E. THE GEFS ENSEMBLE CONTINUES TO DISPLAY HIGH UNCERTAINTY WITH A VERY LARGE SPREAD IN THE SOLUTIONS, WHILE THE ECENS HAS TIGHTENED UP ON A MORE WESTWARD TRACK TOWARDS THE AFRICAN COAST. THE JTWC FORECAST CLOSELY TRACKS THE INTERMEDIATE ECMWF FORECAST, BUT CONFIDENCE IS LOW DUE TO THE LARGE SPREAD IN THE GUIDANCE. INTENSITY GUIDANCE IS FAIRLY GOOD, WITH THE COAMPS-TC (BOTH GFS AND NAVGEM) SHOWING A PEAK AROUND 60 KNOTS, WHILE THE HAFS-A AND HWRF ARE PEAKING AROUND 50 KNOTS. SOMEWHAT SURPRISINGLY, THE ECMWF ENSEMBLE SHOWS A HIGH PROBABILITY OF SIGNIFICANT INTENSIFICATION AND A 20 PERCENT CHANCE OF RI. IF THE ECENS IS SHOWING THAT, ITS PROBABLY A GOOD IDEA TO PAY ATTENTION. THE FORECAST HEDGES A BIT HIGHER THAN THE GUIDANCE BASED ON THE RECENT STRUCTURAL IMPROVEMENTS, AND THE INDICATIONS OF RI IN THE ECENS OUTPUT, BUT CONFIDENCE REMAINS LOW. FORECAST CONFIDENCE: TRACK 0 - 72 HR: LOW INTENSITY 0 - 72 HR: LOW// NNNN