TC 06S(ANGGREK)// TC 07P// Invest 92S// Invest 99S// 2309utc updates

JTWC IS ISSUING 6HOURLY WARNINGS AND 3HOURLY SATELLITE BULLETINS TC 07P. 12HOURLY WARNINGS AND 3HOURLY SATELLITE BULLETINS ARE ISSUED ON TC 06S.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: TROPICAL CYCLONE (TC) 06S HAS MAINTAINED INTENSITY AT 40 KNOTS DUE PRIMARILY TO UPWELLING COOLER WATER RESULTING FROM THE SYSTEM'S SLOW TRACK MOTION AS REVEALED IN THE RECENT HAFS-A SST ANALYSIS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS FRAGMENTED, WEAK DEEP CONVECTIVE BANDING WRAPPING INTO A RAGGED LOW-LEVEL CIRCULATION CENTER (LLCC), WHICH SUPPORTS THE INITIAL POSITION WITH HIGH CONFIDENCE. A 230342Z MHS 89 GHZ MICROWAVE IMAGE SHOWS A 100-110 NM DIAMETER CONVECTION-FREE CORE WITH DEEP CONVECTIVE BANDS WRAPPED LOOSELY. A 230258Z ASCAT-B BULLSEYE IMAGE SHOWS A DEFINED CENTER WITH 30-35 KNOT WINDS OVER THE EASTERN SEMICIRCLE, WHICH SUPPORTS THE INITIAL WIND RADII WITH HIGH CONFIDENCE. ANIMATED WATER VAPOR IMAGERY AND RECENT CIMSS UPPER-LEVEL WINDS SHOW AN UPPER-LEVEL TROUGH IMPINGING ON THE SOUTHERN PERIPHERY OF THE SYSTEM, LIMITING POLEWARD OUTFLOW, WITH MODERATE EQUATORWARD OUTFLOW. THE INITIAL INTENSITY OF 40 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON RECENT ASCAT DATA AS WELL AS THE PGTW, DEMS AND APRF SUBJECTIVE DVORAK ESTIMATES.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TRACK MOTION IS EXPECTED TO REMAIN SLOW AND POSSIBLY ERRATIC UNTIL AFTER TAU 24 WHEN A DOMINANT STR IS FORECASTED TO BUILD TO THE SOUTH AND THEN SOUTHEAST, WHICH WILL ACCELERATE THE SYSTEM WEST-SOUTHWESTWARD THROUGH THE FORECAST PERIOD. AS THE SYSTEM ACCELERATES, THE LIMITING EFFECTS OF THE UPWELLING COOLER WATER WILL LESSEN AND THE SYSTEM WILL INTENSIFY AT A FASTER RATE UP TO A PEAK INTENSITY OF 70-75 KNOTS. AFTER TAU 72, ENVIRONMENTAL CONDITIONS WILL DEGRADE SLIGHTLY WITH SOME DRY AIR ENTRAINMENT AND WEAKER OUTFLOW RESULTING IN A SLIGHT WEAKENING TREND.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT THROUGH TAU 72 WITH A 65 NM CROSS-TRACK SPREAD IN SOLUTIONS AT TAU 72 DIVERGING THROUGH TAU 120. THE 230000Z GFS AND ECMWF ENSEMBLES ALSO SHOW A SIMILAR SPREAD. INTENSITY GUIDANCE REMAINS IN FAIR AGREEMENT THROUGH THE FORECAST PERIOD, LENDING MEDIUM OVERALL CONFIDENCE TO THE JTWC INTENSITY FORECAST.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: TROPICAL CYCLONE (TC) 07P HAS CONTINUED TO STRUGGLE TO ORGANIZE DUE TO THE BROAD UPPER-LEVEL LOW POSITIONED OVER THE CENTER, EXTENDING WESTWARD TO THE AUSTRALIAN GOLD COAST. CONSEQUENTLY, ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS MULTIPLE MESOVORTICIES ROTATING CYCLONICALLY AROUND A BROAD, EXPOSED CENTER, WITH DEEP CONVECTIVE BANDING DISPLACED EASTWARD AND POLEWARD. A 230319Z AMSR2 36 GHZ MICROWAVE IMAGE REVEALS A FAIRLY RAGGED LOW-LEVEL CIRCULATION CENTER (LLCC) WITH FRAGMENTED INNER SHALLOW BANDING WRAPPING AROUND THE LLCC. A RECENT 222243Z ASCAT-B IMAGE REFLECTS THE BROAD NATURE OF THE SYSTEM, SHOWING AN ELONGATED CENTER WITH GALE-FORCE WINDS DISPLACED TO THE NORTHEAST AND SOUTHWEST. THIS ASCAT IMAGE WAS USED TO TAILOR THE INITIAL WIND RADII VALUES. OVERALL, THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON THE CENTROID POSITION EVIDENT IN MSI AND THE AMSR2 IMAGE. THE INITIAL INTENSITY OF 35 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON SUBJECTIVE DVORAK ESTIMATES, RECENT ASCAT DATA AND THE CIMSS OBJECTIVE ESTIMATES.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TC 07P IS TRACKING SLOWLY WITHIN A COMPETING STEERING ENVIRONMENT BUT IS FORECASTED TO TURN WEST-SOUTHWESTWARD AFTER TAU 12 AS THE SUBTROPICAL RIDGE TO THE WEST, OVER EASTERN AUSTRALIA, BUILDS TO THE SOUTH AND BECOMES THE DOMINANT STEERING INFLUENCE THROUGH THE FORECAST PERIOD. OVER THE NEXT DAY, THE UPPER-LEVEL LOW IS EXPECTED TO GRADUALLY ERODE, REPLACED BY UPPER-LEVEL RIDGING. THIS WILL ALLOW THE SYSTEM TO INTENSIFY AT A FASTER RATE TO A PEAK INTENSITY OF 60 KNOTS JUST PRIOR TO LANDFALL NEAR TAU 48. AFTER TAU 48, THE SYSTEM WILL RAPIDLY WEAKEN AS IT TRACKS INLAND, WITH DISSIPATION ANTICIPATED BY TAU 72.

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE REMAINS IN GOOD AGREEMENT WITH A CROSS-TRACK SPREAD OF ONLY 60 NM AT TAU 48. HOWEVER, SIGNIFICANT UNCERTAINTY IN THE INITIAL POSITION WILL CONTINUE THROUGH TAU 24 THUS OVERALL CONFIDENCE IN THE JTWC TRACK FORECAST IS MEDIUM. DUE TO THE COMPLEX, EVOLVING UPPER-LEVEL ENVIRONMENT, THERE IS MEDIUM CONFIDENCE IN THE JTWC INTENSITY FORECAST. RELIABLE INTENSITY GUIDANCE, INCLUDING THE HAFS-A AND COAMPS-TC FORECASTS, INDICATES A PEAK INTENSITY RANGING FROM 45 TO 60 KNOTS. THE 221800Z COAMPS-TC ENSEMBLE INTENSITY PROBABILITIES SHOW LOW PROBABILITY (20 TO 30 PERCENT) OF MODERATE INTENSIFICATION OVER THE NEXT TWO DAYS.

THE AREA OF CONVECTION (INVEST 92S) PREVIOUSLY LOCATED NEAR 17.4S 64.4E HAS BEEN RE-LOCATED NEAR 15.7S 59.5E, APPROXIMATELY 243 NM NORTH-NORTHEAST OF MAURITIUS. THE CONVECTION WAS PREVIOUSLY SCATTERED WITHIN AN ELONGATED TROUGH WITH MULTIPLE WEAK VORTICITY CENTERS AND HAS NOW CONSOLIDATED TO A DISCERNABLE LOW-LEVEL CIRCULATION CENTER (LLCC) THAT IS VISIBLE ON ANIMATED SHORTWAVE INFRARED IMAGERY. SATELLITE ANIMATION ALSO SHOWS THE CONVECTION BEING SHEARED TO THE NORTHWEST LEAVING THE LLCC MOSTLY EXPOSED. ANIMATED TOTAL PRECIPITABLE WATER LOOPS SHOWS DEEP MOISTURE INCREASING AND INSULATING THE CIRCULATION ON THE SOUTHWEST SIDE. ENVIRONMENTAL ANALYSIS INDICATES THAT 92S IS IN A MARGINALLY FAVORABLE ENVIRONMENT FOR FURTHER DEVELOPMENT WITH WEAK EQUATORWARD OUTFLOW ALOFT, MODERATE TO HIGH (20-25 KTS) VERTICAL WIND SHEAR, AND WARM (28-29 C) SEA SURFACE TEMPERATURES. MODEL GUIDANCE INDICATES THAT THE SYSTEM WILL GATHER MOMENTUM AND CONTINUE DEEPENING AND CONSOLIDATING OVER THE NEXT 48 HOURS, PASSING TO THE EAST OF MAURITIUS NEAR 240600Z. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 20 TO 25 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1001 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS UPGRADED TO MEDIUM.

MODEL GUIDANCE INDICATES THAT THE SYSTEM WILL GATHER MOMENTUM AND CONTINUE DEEPENING AND CONSOLIDATING OVER THE NEXT 48 HOURS, PASSING TO THE EAST OF MAURITIUS NEAR 240600Z.