TC 05S(DARIAN) reaches unexpected heights: Super Typhoon intensity//Invest 90S up-graded//Invest 98B//Invest 94W// 2106utc

JTWC IS ISSUING 12HOURLY WARNINGS AND 3HOURLY SATELLITE BULLETINS ON TC 05S(DARIAN).

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: TROPICAL CYCLONE DARIAN HAS EXCEEDED ALL EXPECTATIONS, AND RAPIDLY INTENSIFIED INTO A 130-KNOT MONSTER. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A 30NM WIDE EYE, WITH EYE TEMPERATURES MEASURED AT +7C AT ANALYSIS TIME, NOW MEASURED AT +14C AN HOUR LATER. THE SYSTEM IS EXHIBITING SOME FEATURES OF AN ANNULAR TROPICAL CYCLONE, WITH MINIMAL BANDING FEATURES CONSTRAINED TO THE WESTERN SIDE OF THE CIRCULATION AND AN EYE SURROUNDED BY A RING OF FAIRLY CONSISTENT -75C CLOUD TOPS. THE MOST RECENT MICROWAVE IMAGE WAS AN SSMIS PASS FROM 201218Z WHICH SHOWED A NEARLY COMPLETE EYEWALL, THOUGH STILL OPEN ON THE NORTHEAST SIDE AND THE ONE BANDING FEATURE DISPLACED TO THE WEST. BASED ON THE DRAMATICALLY IMPROVED INFRARED STRUCTURE, IT CAN BE SAFELY ASSUMED THE EYEWALL IS NOW COMPLETELY CLOSED. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE 30NM EYE IN THE EIR. THE INITIAL INTENSITY IS ASSESSED WITH HIGH CONFIDENCE BASED ON A BLEND OF AGENCY FIXES BETWEEN 115-140 KNOTS, WITH A SUPPORT FROM THE ADT (134 KNOTS), AIDT (132 KNOTS), OPEN-AIIR (129 KNOTS) AND THE SATCON OF 121 KNOTS. THE SYSTEM REMAINS COCOONED IN A FAVORABLE ENVIRONMENT CHARACTERIZED BY LOW VERTICAL WIND SHEAR (VWS), MODERATE RADIAL OUTFLOW WITH A SLIGHT BIT OF POLEWARD OUTFLOW AS WELL. SSTS ARE MARGINAL AT 26-27C AND MAY BE SLIGHTLY COOLER DUE TO UPWELLING, BUT CLEARLY THE SYSTEM HAS BEEN ABLE TO OVERCOME THIS MARGINAL PARAMETER.

FORECAST DISCUSSION: TC 05S HAS RAPIDLY INTENSIFIED OVER THE PAST 12 HOURS, FROM 90 KNOTS TO 130 KNOTS IN JUST 18 HOURS. THE SYSTEM HAS TURNED TO THE WEST OVER THE PAST 12 HOURS THOUGH THERE HAS BEEN A BIT OF WOBBLE IN THE TRACK RECENTLY, THE COURSE MADE GOOD IS NOW ALMOST DUE WEST. THE FORECAST CALLS FOR THE TRACK TO TURN MORE WEST-NORTHWEST THROUGH TAU 48 TO TAU 60 AS THE SYSTEM CONTINUES TO TRACK ALONG THE NORTHERN PERIPHERY OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) ENTRENCHED DOWN TO THE SOUTH NEAR 30S. BY TAU 72 THE RIDGE WILL RACE OFF TO THE WEST AND SOUTH AND THE SYSTEM WILL COME UNDER THE STEERING INFLUENCE OF AN EXTENSION OF THE NEAR-EQUATORIAL RIDGE (NER) WHICH WILL BUILD SOUTHWARD TO THE EAST OF THE SYSTEM, LEADING TO A TURN SHARPLY SOUTHWARD BY THE END OF THE FORECAST PERIOD. IN THE NEAR-TERM, DUE TO ITS NEAR-ANNULAR NATURE, AND THE LOW PROBABILITY OF AN EYEWALL REPLACEMENT CYCLE (ERC), THERE IS LITTLE IN THE WAY OF INTENSITY CHANGE ANTICIPATED THROUGH TAU 12. AFTER THIS POINT HOWEVER. A COMBINATION OF FACTORS WILL CONSPIRE TO WEAKEN THE SYSTEM. FIRST, THE RECENT SLOW MOVEMENT HAS UPWELLED CONSIDERABLY COOLER WATERS AROUND THE SYSTEM, AND THE FORECAST TRACK TAKES IT OVER MARGINALLY COOLER WATERS FOR THE NEXT 48 HOURS. THEN AROUND TAU 48, AN UPPER-LEVEL TROUGH IS EXPECTED TO DEEPEN JUST TO THE SOUTHEAST OF TC 05S, WHICH WILL INDUCE SOME CONVERGENT FLOW ALOFT WHICH WILL PUSH DOWN ON THE SYSTEM FROM THE SOUTH. THE FORECAST CALLS FOR THESE FACTORS TO WEAKEN THE SYSTEM DOWN TO 95 KNOTS BY TAU 72. THEREAFTER, ENVIRONMENTAL FACTORS IMPROVE ONCE MORE WITH THE SYSTEM MOVING OVER WARMER WATERS, AND TAPPING INTO IMPROVED POLEWARD OUTFLOW, WITH A SECOND PEAK EXPECTED NEAR 100 KNOTS. BUT THIS SECOND PEAK WILL BE SHORT-LIVED, AS THE SYSTEM SUCCUMBS ONCE AGAIN TO UPWELLING INDUCED SSTS COOLING AND BEGINS TO WEAKEN BY THE END OF THE FORECAST PERIOD.

MODEL DISCUSSION: DETERMINISTIC AND ENSEMBLE TRACK GUIDANCE IS IN GOOD AGREEMENT, PARTICULARLY THROUGH TAU 72, WITH ALL OF THE CONSENSUS MEMBERS CONFINED TO ENVELOPE WHICH GRADUALLY EXPANDS TO 125NM BY TAU 72. THEREAFTER THE MODELS BEGIN TO DIVERGE, WITH THE MAJORITY OF THE GLOBAL MODELS CONTINUING THE TRACK WEST THROUGH TAU 96 WHILE THE MESOSCALE MODELS TURN IT SOUTHWARD. BY TAU 120 HOWEVER, ALL OF THE CONSENSUS MEMBERS AGREE ON THE TURN TO THE SOUTH, THOUGH CROSS-TRACK SPREAD INCREASES TO 225NM BY TAU 120. THE JTWC FORECAST LIES JUST SOUTH OF THE CONSENSUS MEAN THROUGH TAU 72 WITH HIGH CONFIDENCE, THEN LIES TO THE WEST OF THE MEAN THROUGH TAU 120 WITH MEDIUM CONFIDENCE. INTENSITY GUIDANCE IS GOOD AGREEMENT BUT, DUE TO THE FACT THAT NONE OF THE MODELS HAVE PICKED UP ON THE RAPID INTENSIFICATION TREND, THEY ARE REVERTING TOO QUICKLY TO THE BAD INITIALIZATION, AND SHOWING A DRASTIC WEAKENING TREND OF OVER 70 KNOTS IN TWELVE HOURS. THE JTWC FORECAST THEREFORE LIES WELL ABOVE ALL OF THE GUIDANCE THROUGH TAU 72, THOUGH CONFIDENCE IS MEDIUM DUE TO THE UNCERTAINTY SURROUNDING THE INITIALIZATION. THE BULK OF THE GUIDANCE (EXCEPT THE DECAY SHIPS) INDICATES A SECONDARY INTENSIFICATION AFTER TAU 72 WITH A PEAK NEAR TAU 96 FOLLOWED BY ANOTHER ROUND OF WEAKENING THROUGH TAU 120. THE EXTENDED FORECAST LIES JUST SLIGHTLY ABOVE THE CONSENSUS MEAN THROUGH TAU 120 WITH LOW CONFIDENCE.

AN AREA OF CONVECTION (INVEST 90S) HAS PERSISTED NEAR 10.8S 128.1E, APPROXIMATELY 193 NM WEST-NORTHWEST OF DARWIN, AUSTRALIA. ANIMATED EIR DEPICTS AN LLC OBSCURED BY DISORGANIZED FLARING CONVECTION. ENVIRONMENTAL ANALYSIS INDICATES 90S IS IN A MARGINALLY FAVORABLE ENVIRONMENT FOR DEVELOPMENT WITH MODERATE TO HIGH (20-30 KNOT) VWS OFFSET BY GOOD DIVERGENCE ALOFT. SSTS ARE VERY WARM (30-31C) WITH VERY HIGH OHC ABOVE 180 KJ/CM2. GLOBAL MODELS ARE IN GOOD AGREEMENT THAT 90S WILL CONTINUE TO TRACK SOUTHWARD OVER THE NEXT 24- 48 HOURS AND POSSIBLY INTENSIFY RAPIDLY AS IT TRACKS INTO AN AREA OF DECREASING VWS BEFORE IT MAKES LANDFALL OVER THE KIMBERLEY COAST. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 23 TO 28 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 999 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS UPGRADED TO MEDIUM.

GLOBAL MODELS ARE IN GOOD AGREEMENT THAT 90S WILL CONTINUE TO TRACK SOUTHWARD OVER THE NEXT 24- 48 HOURS AND POSSIBLY INTENSIFY RAPIDLY AS IT TRACKS INTO AN AREA OF DECREASING VWS BEFORE IT MAKES LANDFALL OVER THE KIMBERLEY COAST.

AN AREA OF CONVECTION (INVEST 98B) HAS PERSISTED NEAR 5.8N 86.6E, APPROXIMATELY 330 NM EAST OF COLOMBO, SRI LANKA. ANIMATED EIR AND A 201942Z AMSR2 89GHZ MICROWAVE IMAGE DEPICT A BROAD LLC PARTIALLY EXPOSED TO THE SOUTHEAST OF FLARING CONVECTION THAT IS BEING SHEARED TO THE NORTHWEST. ENVIRONMENTAL ANALYSIS INDICATES 98B IS IN A MARGINALLY FAVORABLE ENVIRONMENT FOR DEVELOPMENT WITH LOW TO MODERATE (10-20 KNOT) VWS OFFSET BY GOOD DIVERGENCE ALOFT AND WARM (28-29C) SEA SURFACE TEMPERATURES. GLOBAL MODELS ARE IN GOOD AGREEMENT THAT 98W WILL CONTINUE TO TRACK GENERALLY NORTH OVER THE NEXT 24-48 HOURS AND GRADUALLY INTENSIFY HOWEVER, THE INCREASING VWS WILL LIKELY HINDER DEVELOPMENT INTO A SIGNIFICANT TROPICAL CYCLONE. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 23 TO 28 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1004 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS UPGRADED TO LOW.