Intensifying TC 06P(TIFFANY): overshooting tops and microwave eye// TC 05P up-date, 09/15utc

JTWC IS ISSUING 6HOURLY WARNINGS AND 3HOURLY SATELLITE BULLETINS ON TC 05P AND TC 06P(TIFFANY).

09/1350UTC.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: WHILE THE SYSTEM HAS BEEN MOVING SOUTHEAST AT A FAIRLY QUICK 20 KM/H OVER THE PAST SIX HOURS, OVER THE LAST COUPLE OF HOURS IT HAS SHOWN SIGNS OF STARTING TO SLOW DOWN. THIS TREND IS EXPECTED TO CONTINUE OVER THE NEXT 12 HOURS AS THE NER TO THE NORTHEAST WEAKENS AND MOVES AWAY TO THE NORTH. OVER THE NEXT 18 HOURS, THE STR TO THE SOUTH WILL BUILD IN AND BECOME THE PRIMARY STEERING MECHANISM AND TC 05P WILL TURN TO THE WEST BY 24H. BY 36H, THE STEERING PATTERN SHIFTS AGAIN, WITH THE A MAJOR SHORTWAVE TROUGH MOVING IN FROM THE WEST AND ERODING THE STR, ALLOWING TC 05P TO TURN SHARPLY SOUTH-SOUTHEASTWARD FROM 48H THROUGH THE END OF THE FORECAST PERIOD. THE SYSTEM CURRENTLY SITS AT THE BASE OF AN UPPER-LEVEL TROUGH, AND THE STRONG DIVERGENT POLEWARD OUTFLOW ON THE EASTERN SIDE OF THE SYSTEM HAS ALLOWED FOR THE RECENT INTENSIFICATION. MID-LEVEL DRY AIR IN THE WESTERN SEMICIRCLE REMAINS PROBLEMATIC HOWEVER AND IS LIMITING THE INTENSIFICATION FOR NOW. THE ATMOSPHERE IS EXPECTED TO MOISTEN OVER THE NEXT 12 HOURS, ALLOWING FOR A SHORT SPURT OF INTENSIFICATION TO 45 KNOTS. THE BASE OF THE UPPER TROUGH PINCHES OFF TO AN UPPER-LEVEL LOW OVER THE NEXT 12 HOURS, AND TC 05P WILL MOVE UNDER THIS FEATURE BY 24H, AND THE CONVERGENCE FLOW ALOFT WILL LEAD TO A BRIEF WEAKENING TREND THROUGH 48H. THE SYSTEM IS EXPECTED TO ONCE AGAIN INTENSIFY AS IT MOVES AWAY FROM THE UPPER LOW, DEVELOPS A WEAK ANTICYCLONE ALOFT AND TAPS INTO STRONG POLEWARD OUTFLOW, PEAKING AT 50 KNOTS AT 72H. THE SYSTEM IS FORECAST TO CROSS THE 26C ISOTHERM SHORTLY AFTER 72H, AND FACE INCREASING SHEAR AND DRY AIR ENTRAINMENT. SUBTROPICAL TRANSITION WILL BEGIN BY 96H, AND BE COMPLETE NO LATER THAN 120H.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS CYCLING CONVECTION NEAR AND OBSCURING THE ASSESSED LOW LEVEL CIRCULATION CENTER (LLCC). THE CONVECTIVE MASS WAS VERY COMPACT, BUT WELL DEFINED AT THE 1200Z HOUR, SUBSEQUENTLY WEAKENED AND BECAME DISORGANIZED, BUT IS ONCE AGAIN FLARING BY THE 1330Z HOUR. UNFORTUNATELY THERE HAS BEEN NO RECENT MICROWAVE IMAGERY, BUT 090924Z ASCAT-B AND 091019 ASCAT-C PASSES SHOWED THE COMPACT CIRCULATION CENTER TO GOOD EFFECT, AND AN EXTRAPOLATION OF THESE CENTERS PROVIDED MEDIUM CONFIDENCE TO THE INITIAL POSITION. THE SCATTEROMETER PASSES SHOWED 35 KNOT WINDS WITHIN 110KM OF THE CENTER TO BOTH THE NORTHWEST AND SOUTH OF THE CENTER, AND PROVIDED GOOD SUPPORT TO INCREASE THE INITIAL INTENSITY TO 35 KNOTS. AGENCY CURRENT INTENSITY ESTIMATES ROUGHLY ALIGNED WITH THE SCATTEROMETER MEASUREMENTS AND GAVE HIGH CONFIDENCE TO THE INITIAL INTENSITY.

090924Z ASCAT-B AND 091019 ASCAT-C PASSES SHOWED THE COMPACT CIRCULATION CENTER TO GOOD EFFECT, AND AN EXTRAPOLATION OF THESE CENTERS PROVIDED MEDIUM CONFIDENCE TO THE INITIAL POSITION. THE SCATTEROMETER PASSES SHOWED 35 KNOT WINDS WITHIN 110KM OF THE CENTER TO BOTH THE NORTHWEST AND SOUTH OF THE CENTER, AND PROVIDED GOOD SUPPORT TO INCREASE THE INITIAL INTENSITY TO 35 KNOTS.

MODEL DISCUSSION: THE BULK OF THE TRACK GUIDANCE IS IN GOOD AGREEMENT, WITH THE EXCEPTION OF THE NAVGEM AND HWRF SOLUTIONS, WHICH TAKE THE SYSTEM MUCH FURTHER SOUTHEAST THROUGH 72H, WHERE THEY REJOIN THE REMAINDER OF THE GUIDANCE. ALONG TRACK SPREAD INCREASES DRAMATICALLY AFTER 72H, AS THE SYSTEM UNDERGOES SUBTROPICAL TRANSITION, WITH THE NAVGEM FAR OUTPACING ALL OTHER CONSENSUS MEMBERS IN FORWARD SPEED. THE JTWC TRACK REMAINS CONSISTENT WITH THE PREVIOUS FORECAST, AND IS ON THE SOUTHERN SIDE OF THE GUIDANCE THROUGH 36H, THEN ON THE INSIDE EDGE OF THE ENVELOPE THROUGH THE REMAINDER OF THE FORECAST. OVERALL CONFIDENCE IS MEDIUM IN THE NEAR TERM, AND LOW IN THE EXTENDED FORECAST. INTENSITY GUIDANCE MEMBERS ALL AGREE ON NEAR-TERM INTENSIFICATION, PEAKING BETWEEN 45 AND 50 KNOTS, FOLLOWED BY A WEAKENING THROUGH 36H, THEN REINTENSIFICATION TO A PEAK BETWEEN 50 AND 60 KNOTS. THE JTWC FORECAST FOLLOWS THE OVERALL TREND, BUT REMAINS 5-10 KNOTS LOWER THAN THE CONSENSUS MEAN. CONFIDENCE IS MEDIUM TRENDING TO LOW.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TROPICAL CYCLONE TIFFANY CONTINUES TO RAPIDLY INTENSIFY AS IT TRACKS WEST TOWARDS THE EAST COAST OF AUSTRALIA. THE SYSTEM IS FORECAST TO TRACK GENERALLY WESTWARD THROUGH THE MAJORITY OF THE FORECAST PERIOD UNDER THE STEERING INFLUENCE OF THE STR ENTRENCHED OVER CENTRAL AUSTRALIA. TC 06P WILL MAKE LANDFALL JUST WEST OF CAPE FLATTERY WITHIN THE NEXT 24 HOURS, THOUGH IT IS POSSIBLE THAT A SLIGHT JOG SOUTHWARD WILL INCUR A LANDFALL ON CAPE FLATTERY CLOSER TO 12H. THE ULTIMATE PEAK NEAR-TERM INTENSITY WILL DEPEND UPON THE LANDFALL POINT AND TIMING, WITH AN EARLIER LANDFALL RESULTING IN A LOWER PEAK. THE UPPER-LEVEL ENVIRONMENT HAS IMPROVED OVER THE PAST SIX HOURS, WITH CIMSS SHEAR ESTIMATES DOWN TO 15-20 KNOTS OF EASTERLY SHEAR. BEING IN-PHASE WITH THE STORM MOTION, RELATIVE SHEAR IS EVEN LOWER, RESULTING IN THE INTENSIFICATION SEEN THUS FAR. PEAK INTENSITY IS FORECAST TO REACH 60 KNOTS PRIOR TO LANDFALL, THOUGH IF THE SYSTEM REMAINS OVER WATER TO THE NORTH OF CAPE FLATTERY, IT IS POSSIBLE IT COULD BE A BIT STRONGER JUST PRIOR TO LANDFALL. ONCE ASHORE THE SYSTEM WILL WEAKEN DUE TO TERRAIN INTERACTION, THOUGH IT IS STILL EXPECTED TO EMERGE INTO THE GULF OF CARPENTARIA AT TROPICAL STORM STRENGTH AROUND 36H. ONCE OVER THE VERY WARM, SHALLOW WATERS OF THE GULF, THE SYSTEM WILL REINTENSIFY, REACHING A SECOND PEAK OF 65 KNOTS/CAT 1 US JUST PRIOR TO A SECOND LANDFALL AT GROOTE EYLANDT NEAR 72H. THE SYSTEM WILL GRADUALLY TURN SOUTHWARD IN A GRACEFUL ARC INTO A BREAK IN THE STEERING RIDGE, ULTIMATELY MOVING INLAND OVER NORTHERN AUSTRALIA AND STEADILY WEAKENING THROUGH 120H.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A COMPACT SYSTEM WITH DEEP CONVECTIVE BANDS SPIRALING INTO THE LOW LEVEL CIRCULATION CENTER. WHILE THE LLCC IS OBSCURED THE CYCLONIC CIRCULATION EVIDENT IN THE HIGH RESOLUTION EIR ANIMATION, AS WELL AS AN EXTRAPOLATION OF A MICROWAVE EYE FEATURE IN A 090846Z SSMIS 89GHZ MICROWAVE IMAGE PROVIDE MEDIUM CONFIDENCE TO THE INITIAL POSITION. THE PRESENCE OF OVERSHOOTING TOPS WITH TEMPERATURES APPROACHING -90C AND SEVERAL INNER CORE LIGHTNING BURSTS SUPPORT THE RAPID INTENSIFICATION OF THE SYSTEM, WITH THE INITIAL INTENSITY INCREASED TO A CONSERVATIVE 50 KNOTS. AGENCY FIXES ARE SPREAD BETWEEN T2.5 (35 KTS) AND T3.5 (55 KTS) WHILE THE OBJECTIVE ESTIMATES ARE CLOSER TO THE LOWER END OF THE SPREAD. THE INITIAL INTENSITY IS SET SLIGHTLY ABOVE THE AVERAGE OF THE CURRENT INTENSITY ESTIMATES IN LIGHT OF A 090805Z SMOS PASS WHICH SHOWED AN AREA OF 50-55 KNOT WINDS ASSOCIATED WITH THE CORE OF THE SYSTEM.

TC 06P: OF OVERSHOOTING TOPS WITH TEMPERATURES APPROACHING -90C

TC 06P: INNER CORE LIGHTNING BURSTS

MICROWAVE EYE FEATURE.

MODEL DISCUSSION: TRACK GUIDANCE IS IN RELATIVELY GOOD AGREEMENT, WITH THE NOTABLE EXCEPTION OF NAVGEM TO THE SOUTH, AND THE GFS WHICH CONTINUES TO TAKE THE SYSTEM WESTWARD AT AN EXTREMELY FAST RATE. THE REMAINDER OF THE GUIDANCE PACKAGE IS CLOSELY PACKED ABOUT THE CONSENSUS MEAN THROUGH 120H. THE JTWC TRACK LIES ON THE NORTHERN EDGE OF THE TIGHTEST GROUPING OF MODELS AND SLIGHTLY NORTH OF THE CONSENSUS MEAN WHICH IS BEING PULLED SOUTH BY THE NAVGEM. OVERALL TRACK CONFIDENCE IS MEDIUM THROUGH 72H, AND LOW THEREAFTER. INTENSITY GUIDANCE, WITH THE EXCEPTION OF GFS, ALL SUPPORT THE FORECAST TREND LINE, THOUGH DIFFER ON THE PEAKS AND TROUGHS OF THE FORECAST. THE COAMPS-TC FORECAST REMAINS THE MOST AGGRESSIVE, WHILE THE GFS IS THE LEAST. THE JTWC FORECAST MATCHES THE COAMPS-TC THROUGH 36H, THEN IS BELOW THE PEAK COAMPS-TC PEAK OF 90 KNOTS, MORE CLOSELY TRACKING THE HWRF THROUGH THE REMAINDER OF THE FORECAST. CONFIDENCE IS MEDIUM TRENDING TO LOW.