TC 11S(FREDDY) moving westwards,re-intensifying//TC 13S(DINGANI)poleward&decaying//12P:subtropical//Invest 91P//Invest 99W//1409utc

JTWC IS ISSUING 12HOURLY WARNINGS ON TC 11S(FREDDY) AND TC 13S(DINGANI).3HOURLY SATELLITE BULLETINS ARE ISSUED ON TC 11S, TC 13S AND STS 12P(GABRIELLE).

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS DEEP CONVECTION WRAPPING INTO A RAGGED, CLOUD-FILLED EYE. DEEP CONVECTION IN ENHANCED INFRARED SATELLITE IMAGERY IS CONCENTRATED IN THE DOWN-SHEAR RIGHT QUADRANT, WHICH IS INDICATIVE OF THE CONTINUED PRESENCE OF EASTERLY VERTICAL WIND SHEAR. A 132310Z SSMIS 91GHZ MICROWAVE IMAGE REVEALS A 20 NM MICROWAVE EYE, LENDING HIGH CONFIDENCE IN THE INITIAL POSITION. THE INITIAL INTENSITY OF 85 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON A BLEND OF CIMSS SATCON, ADT, ATMS, SSMIS, AND INTERAGENCY DVORAK ESTIMATES. A 131548Z METOP-C ASCAT IMAGE WAS USED TO ADJUST THE INITIAL WIND RADII.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TROPICAL CYCLONE 11S IS FORECAST TO TRACK WESTWARD THROUGH THE FORECAST PERIOD ALONG THE NORTHERN PERIPHERY OF THE SUBTROPICAL RIDGE (STR) TO THE SOUTH. THE SYSTEM HAS GONE THROUGH SEVERAL WEAKENING AND INTENSIFICATION CYCLES, AND THIS TREND IS EXPECTED TO CONTINUE THROUGH THE FORECAST PERIOD. TC 11S HAS SLIGHTLY WEAKENED IN RESPONSE TO EASTERLY VERTICAL WIND SHEAR (15 TO 20 KNOTS), BUT THIS SHEAR IS EXPECTED TO WEAKEN OVER THE NEXT 12 TO 24 HOURS. AFTER THIS TIME, THE SYSTEM WILL REINTENSIFY TO A PEAK OF 110 KNOTS BY TAU 72. AFTER TAU 72, SEA SURFACE TEMPERATURES ARE EXPECTED TO COOL SLIGHTLY ALONG THE FORECAST TRACK, WITH VERTICAL WIND SHEAR ONCE AGAIN INCREASING, RESULTING IN ANOTHER WEAKENING PHASE.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT THROUGH THE FORECAST PERIOD WITH AN 85 NM CROSS-TRACK SPREAD AT TAU 72 AND 275 NM BY TAU 120. THERE IS HIGH CONFIDENCE IN THE FORECAST TRACK THROUGH TAU 72. THEREAFTER, THE NAVGEM IS THE SOUTHERNMOST OUTLIER, SO THE FORECAST TRACK IS PLACED SLIGHTLY NORTH OF CONSENSUS WITH MEDIUM CONFIDENCE. INTENSITY GUIDANCE AGREES ON SLIGHT WEAKENING THROUGH TAU 24 FOLLOWED BY INTENSIFICATION THROUGH TAU 72. GIVEN THE MODERATELY LARGE SPREAD IN SOLUTIONS REGARDING PEAK INTENSITY, THERE IS MEDIUM CONFIDENCE IN THE JTWC INTENSITY FORECAST THROUGH TAU 72 AND LOW CONFIDENCE BEYOND.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A PARTIALLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) LOCATED TO THE NORTH OF A MASS OF CONVECTION WITH RAGGED FEEDER BANDS IN THE NORTHERN PERIPHERY. A PARTIAL 131956Z AMSR2 IMAGE SHOWS THE LLCC BEGINNING TO BE DECOUPLED FROM THE PARENT MASS OF CONVECTION TO THE SOUTH. A PARTIAL 140439Z ASCAT-C PASS SHOWS 40-45 KNOT WINDS IN THE WESTERN PERIPHERY APPROX 75 NM AWAY FROM THE ASSESSED LLCC. TC 13S IS IN AN UNFAVORABLE ENVIRONMENT FOR FURTHER TROPICAL DEVELOPMENT WITH GOOD (40-50 KTS) POLEWARD OUTFLOW ALOFT AND BORDERLINE WARM (26-27 C) SEA SURFACE TEMPERATURES (SST), OFFSET BY STRONG (45-50 KTS) VERTICAL WIND SHEAR (VWS). THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON THE AFOREMENTIONED MSI. THE INITIAL INTENSITY OF 60 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON A BLEND OF THE PGTW DVORAK ESTIMATE AND MULTIPLE AUTOMATED DVORAK ESTIMATES.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TC 13S CONTINUES ITS SOUTH-SOUTHWESTWARD TRACK AS IT RIDES THE WESTERN PERIPHERY OF THE STR. THE SYSTEM IS EXPECTED TO REMAIN ON THIS TRACK UNTIL TAU 48. AFTER TAU 48, TC 13S WILL MAKE A DRAMATIC TURN AND BEGIN TO HEAD SOUTHEASTWARD AS IT FALLS UNDER THE INFLUENCE OF THE SUBTROPICAL JET THAT IS POLEWARD OF APPROXIMATELY 30 DEGREES SOUTH. ENVIRONMENTAL CONDITIONS WILL CONTINUE TO DETERIORATE WITH INCREASED VWS, COPIOUS AMOUNTS OF DRY AIR ENTRAINMENT, AND COOLER (25-26 C) SSTS. TC DINGANI WILL CONTINUE ITS WEAKENING TREND AND COMPLETELY DISSIPATE BY THE END OF THE FORECAST TRACK.

MODEL DISCUSSION: AS OPPOSED TO PREVIOUS MODEL RUNS, THE DETERMINISTIC AND ENSEMBLE MODEL GUIDANCE ARE IN BETTER AGREEMENT THROUGH TAU 72. ALL MEMBERS AGREE ON THE SHIFT IN TRACK AFTER TAU 48 WITH AN OVERALL SPREAD OF 90 NM. OF THE CONSENSUS MEMBERS, NAVGEM IS THE OUTLIER WITH A TRACK WELL TO THE WEST OF THE FORECAST ENVELOPE. BECAUSE OF THIS, THE JTWC FORECAST TRACK IS PLACED SLIGHTLY EAST OF CONSENSUS WITH MEDIUM CONFIDENCE. THE INTENSITY GUIDANCE IS ALSO IN TIGHT AGREEMENT SHOWING AN OVERALL DECREASE DUE TO THE DETERIORATING ENVIRONMENT. THE JTWC INTENSITY FORECAST IS SET WITH HIGH CONFIDENCE.

THE AREA OF CONVECTION (INVEST 91P) PREVIOUSLY LOCATED NEAR 13.2S 137.5E IS NOW LOCATED NEAR 13.5S 136.7E, APPROXIMATELY 239 NM NORTHWEST OF MORNINGTON ISLAND, AUSTRALIA. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) AND RADAR IMAGERY DEPICT A BROAD AND ELONGATED LOW-LEVEL CIRCULATION (LLC) PARTIALLY OBSCURED BY DISORGANIZED CONVECTION IN THE SOUTHEASTERN SEMICIRCLE. A PARTIAL 140021Z ASCAT-B PASS REVEALS 30KT WINDS ALONG THE SOUTHERN PERIPHERY OF THE ASSESSED TROUGH. ENVIRONMENTAL ANALYSIS REVEALS THAT INVEST 91P IS IN A MARGINALLY FAVORABLE ENVIRONMENT DUE MODERATE TO HIGH (20-30KT) VWS, OFFSET BY MODERATE POLEWARD OUTFLOW ALOFT AND VERY WARM (29-30C) SST. GLOBAL MODELS GENERALLY AGREE THAT INVEST 91P SLOWLY DEEPEN IN A SOUTHEASTWARD TRAJECTORY BEFORE RECURVING SOUTHWEST, AND MAKING LANDFALL OVER NORTHERN AUSTRALIA. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 25 TO 30 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 REMAINS MEDIUM.

THE AREA OF CONVECTION (SUBTROPICAL STORM 12P) PREVIOUSLY LOCATED NEAR 35.7S 176.3E IS NOW LOCATED NEAR 36.7S 178.2E, APPROXIMATELY 164 NM EAST OF AUCKLAND, NEW ZEALAND. THE SYSTEM IS CURRENTLY CLASSIFIED AS A SUBTROPICAL STORM (SS), GENERALLY CHARACTERIZED AS HAVING BOTH TROPICAL AND MIDLATITUDE CYCLONE FEATURES. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A FULLY EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) WITH BANDS OF CONVECTION WRAPPING INTO THE CENTER, WITH THE DEEPEST CONVECTION IN THE SOUTHERN SEMICIRCLE. A PARTIAL 132158Z ASCAT-C PASS SHOWS 40 KNOT WINDS IN THE WESTERN SEMICIRCLE OVER THE WATERS WEST OF THE NORTH ISLAND OF NEW ZEALAND. MOREOVER, A 140400Z SURFACE OBSERVATION FROM CAPE REINGA (93004) INDICATE SOUTHWESTERLY WINDS OF 45 KNOTS. THE SYSTEM HAD A SMALL PERIOD OF QUASI-STATIONARY LIKE BEHAVIOR BEFORE MAKING A DRAMATIC TURN TO EAST WHILE OVER THE BAY OF PLENTY. THIS CHANGE OF DIRECTION IS LIKELY DUE TO LAND INTERACTION. SS 12P CONTINUES TO BE EMBEDDED UNDER STRONG UPPER-LEVEL WESTERLIES IN HIGH (40-60KT) VWS. SSTS REMAIN UNFAVORABLE FOR TROPICAL DEVELOPMENT AT 20C. GLOBAL MODELS AGREE THAT SS 12P WILL SLOWLY TRACK SOUTHEASTWARD OVER THE NEXT 24-48 HOURS WHILE FILLING AND WEAKENING IN INTENSITY. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 45 TO 50 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 985 MB. FOR HAZARDS AND WARNINGS, REFERENCE THE FLEET WEATHER CENTER SAN DIEGO HIGH WINDS AND SEAS PRODUCT OR REFER TO LOCAL WMO DESIGNATED FORECAST AUTHORITY. THE POTENTIAL FOR TRANSITION INTO A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS REMAINS LOW.