TC 08S intensifying,rapidly moving towards MADA//TC 09P intensifying// Invest 90S//Invest 92P//3 week GTHO maps// 1803utc

JTWC IS ISSUING 6HOURLY WARNINGS ON TC 09P AND 12HOURLY WARNINGS ON TC 08S. 3HOURLY SATELLITE BULLETINS ARE ISSUED ON BOTH SYSTEMS.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS CURVED BANDS OF DEEP CONVECTION WITH A MAJORITY OF THE VERTICAL HOT TOWERS PERSISTING IN THE SOUTHERN SEMICIRCLE. A 171612Z AMSU-B 89GHZ MICROWAVE IMAGE REVEALS PROMINENT LOW LEVEL CLOUD LINES WRAPPING INTO A LOW LEVEL CIRCULATION TUCKED UNDER AND THEREFOR OBSCURED BY THE PRIMARY DEEP CONVECTIVE TOWERS. A 171356Z SMAP MICROWAVE RADIOMETER PASS REVEALED A REGION OF 35-37 KNOT WINDS, WHICH ROUGHLY CORRELATE TO THE PRIMARY REGION OF DEEP CONVECTION. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON EIR AND AMSU-B IMAGERY. THE INITIAL INTENSITY OF 35 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON EARLIER RADIOMETER DATA INDICATING 35-37 KNOTS AND PGTW DVORAK INTENSITY ESTIMATES SLIGHTLY LAGGED BEHIND SHOWING T2.0. THE AFOREMENTIONED CONVECTIVE FEATURE TO THE SOUTH, IF PERSISTENT, COULD INDICATE A BANDING FEATURE THAT WOULD MOVE THE PGTW DVORAK INTENSITY ESTIMATE NORTH OF T2.0.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY. FORECAST DISCUSSION: TC 08S IS FORECAST TO CONTINUE TRACKING GENERALLY WESTWARD UNDER THE STEERING INFLUENCE OF A STR TO THE SOUTH-SOUTHEAST. CURRENTLY IN A HIGHLY FAVORABLE ENVIRONMENT CHARACTERIZED BY WARM SEA SURFACE TEMPERATURES, LOW VERTICAL WIND SHEAR AND SOLID POLEWARD OUTFLOW ALOFT PROVIDED BY AN UPPER-LEVEL ANTICYCLONE TO THE EAST, THE PROBABILITY OF RAPID INTENSIFICATION IN THE COMING HOURS IS HIGH. OVER THE NEXT 12 HOURS AS 08S CONTINUES TO TRACK WESTWARD AND INTENSIFY, INVEST 90S WILL CLOSE WITHIN 400NM AND BEGIN TO ORBIT AND EVENTUALLY FULLY MERGE WITH 08S. BY TAU 24, 08S IS FORECAST TO REACH A PEAK INTENSITY NEAR 60KTS THOUGH HIGHER VALUES ARE POSSIBLE IF HIGHLY FAVORABLE CONDITIONS PERSIST. AFTER TAU 24, THE SYSTEM WILL TRACK WEST-SOUTHWESTWARD AND EVENTUALLY SOUTHWESTWARD TOWARDS A COL REGION AS THE STEERING RIDGE REORIENTS LONGITUDINALLY. NEAR TAU 36, 08S WILL MAKE LANDFALL OVER THE MOUNTAINOUS REGION OF NORTHERN MADAGASCAR. BASED ON THE FORECAST STEERING PATTERN THE SYSTEM WILL BE FORCED INLAND AND RIPPED APART UNTIL DISSIPATION NEAR TAU 72. THERE IS A POTENTIAL HOWEVER, THAT THE STEERING RIDGE WILL BE BROKEN DOWN AND REORIENTED SOONER THAN FORECAST WHICH WOULD ALLOW FOR A POLEWARD TRACK ALONG THE EASTERN COAST OF MADAGASCAR OVER THE WARM WATERS OF THE SOUTHERN IO ALLOWING FOR A LONGER LIFE CYCLE.

MODEL DISCUSSION: WITH THE EXCEPTION OF NAVGEM, NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT THROUGH TAU 36 WITH ALL MEMBERS TRACKING INLAND, CONSISTENT WITH THE JTWC FORECAST TRACK. AFTER MAKING LANDFALL, INDIVIDUAL MEMBERS STRUGGLE TO RESOLVE THE TOPOGRAPHICAL IMPACTS RESULTING IN A SPREADING OF SOLUTIONS THROUGH THE FORECAST PERIOD. FOR THIS REASON THE JTWC TRACK FORECAST IS PLACED WITH MEDIUM CONFIDENCE. RELIABLE MODEL INTENSITY GUIDANCE IS IN GOOD AGREEMENT THROUGH THE FORECAST PERIOD WITH ALL MEMBERS INDICATING A SHARP INTENSIFICATION TREND THROUGH TAU 24, AFTER WHICH AN EQUALLY SHARP WEAKENING TREND AS THE SYSTEM MAKES LANDFALL, AFTER WHICH STEADY WEAKENING UNTIL DISSIPATION. THE JTWC INTENSITY GUIDANCE IS THEREFOR PLACED WITH HIGH CONFIDENCE.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A PARTIALLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) WITH TWO PRIMARY SPIRAL BANDS OF DEEP CONVECTION. A 172200Z ASCAT-B SCATTEROMETERY PARTIAL PASS SHOWS THE EASTERN SEMICIRCLE OF TC 09P WHICH INDICATES A RELATIVELY COMPACT CIRCULATION WITH A FIELD OF 35KT WINDS TO THE NORTHEAST OF THE LLCC. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON MSI AND PARTIAL ASCAT-B IMAGERY. THE INITIAL INTENSITY OF 35 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON AGENCY DVORAK CURRENT INTENSITY ESTIMATES WHICH INDICATE 30-35KTS HOWEVER BOTH PGTW AND KNES SHOW A FINAL T OF T2.0 DUE TO CONSTRAINTS, WHILE THEIR DATA T NUMBERS ARE T2.5, SO THE TRUE CONSENSUS IS NEAR 35KTS.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY. FORECAST DISCUSSION: TC 09P IS FORECAST TO CONTINUE TRACKING EAST-SOUTHEASTWARD IN A FAVORABLE ENVIRONMENT CHARACTERIZED BY WARM SEA SURFACE TEMPERATURES (SST), LOW VERTICAL WIND SHEAR (VWS), AND SOLID DUAL CHANNEL OUTFLOW ALOFT. OVER THE NEXT 24 HOURS, AS THE SYSTEM THREADS THE NEEDLE BETWEEN VANUATU TO THE NORTH AND NEW CALEDONIA TO THE SOUTH, 09P IS FORECAST TO REACH A PEAK INTENSITY OF 50KTS AND POSSIBLY A BIT HIGHER. BY TAU 36 AND THROUGH TAU 48, THE SYSTEM WILL TURN SLIGHTLY POLEWARD AND STEADY UP ON A SOUTHEASTERLY COURSE. DURING THIS TIME THE ENVIRONMENT WILL BEGIN TO DEGRADE, CHARACTERIZED BY INCREASING DRY AIR ENTRAINMENT, COOLING SEA SURFACE TEMPERATURES, DECREASED OUTFLOW ALOFT AND BAROCLINIC INTERACTION. BY TAU 48, 09P WILL BEGIN SUBTROPICAL TRANSITION (STT) AS IT IS FORCED FURTHER POLEWARD BY A BUILDING SUBTROPICAL RIDGE (STR) TO THE EAST. AFTER TAU 48, HAVING CROSSED THE 26C ISOTHERM, NOW POLEWARD OF THE STR AXIS AND UNDER INCREASING DRY AIR ENTRAINMENT 09P WILL GRADUALLY LOSE ALL TROPICAL CHARACTERISTICS AS IT CONTINUES TO WEAKEN BELOW 35KTS. BY TAU 96, NOW DEVOID OF ALL TROPICAL CHARACTERISTICS AND SOUTH OF THE 30TH PARALLEL, 09P WILL COMPLETE STT AND CONTINUE POLEWARD EVENTUALLY BECOMING EXTRA-TROPICAL BEYOND THE FORECAST PERIOD.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT WITH A 100NM SPREAD IN SOLUTION THROUGH TAU 72. AFTER TAU 72 AS THE SYSTEM COMPLETES STT MODEL GUIDANCE BEGINS TO SPREAD THROUGH THE FORECAST PERIOD. FOR THESE REASONS THE INITIAL JTWC TRACK GUIDANCE IS PLACED WITH HIGH CONFIDENCE AND THE EXTENDED TRACK GUIDANCE IS PLACED WITH MEDIUM CONFIDENCE. RELIABLE MODEL INTENSITY GUIDANCE IS IN FAIR AGREEMENT THAT AN INITIAL INTENSIFICATION TREND WILL PERSIST THROUGH TAU 36, AFTER WHICH ALL MEMBERS EXCEPT DECAY-SHIPS (NAVGEM AND GFS) WEAKEN THE SYSTEM THROUGH THE FORECAST PERIOD. FOR THESE REASONS THE INITIAL JTWC INTENSITY FORECAST IS PLACED WITH HIGH CONFIDENCE WHILE THE EXTENDED INTENSITY FORECAST IS PLACED WITH MEDIUM CONFIDENCE.

AN AREA OF CONVECTION (INVEST 92P) HAS PERSISTED NEAR 18.6S 148.8E, APPROXIMATELY 202 NM EAST-SOUTHEAST OF CAIRNS, AUSTRALIA. ANIMATED MULTI-SPECTRAL IMAGERY AND A 172032Z SSMIS 37GHZ MICROWAVE PASS SHOW DEEP FLARING CONVECTION IN THE SOUTHEAST QUADRANT WRAPPING INTO A PARTIALLY EXPOSED AND GRADUALLY CONSOLIDATING LLCC. A 172340Z METOP-B ASCAT PASS DEPICTS A 25-30KT WIND FIELD WITHIN THE SOUTHERN SEMI-CIRCLE REVEALING A DEFINED CLOSED CIRCULATION. ENVIRONMENTAL ANALYSIS REVEALS FAVORABLE CONDITIONS FOR DEVELOPMENT AS INDICATED BY WEAK (15-20KT) VWS, WARM (28- 29C) SEA SURFACE TEMPERATURES, AND GOOD POLEWARD AND EQUATORWARD OUTFLOW. GLOBAL MODELS ARE IN AGREEMENT THAT THE 92P WILL BRIEFLY TRACK NORTHEASTWARD BEFORE RECURVING EAST-SOUTHEASTWARD AND CONTINUE INTENSIFYING. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 27 TO 30 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1002 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS MEDIUM.

THE AREA OF CONVECTION (INVEST 90S) PREVIOUSLY LOCATED NEAR 8.7S 54.6E IS NOW LOCATED NEAR 8.5S 54.8E, APPROXIMATELY 727 NM NORTH- NORTHWEST OF MAURITIUS. ANIMATED MULTI-SPECTRAL IMAGERY AND A 171428Z SSMIS 37GHZ MICROWAVE PASS DEPICT DEEP FLARING CONVECTION ON THE WESTERN SEMICIRCLE WRAPPING INTO A PARTIALLY OBSCURED LLCC. A RECENT SCATTEROMETRY PASS SHOWS 25-30KT WINDS ON THE WESTERN FLANK. ENVIRONMENTAL ANALYSIS REVEALS UNFAVORABLE CONDITIONS FOR FURTHER INTENSIFICATION DUE TO STRONG (30-40KT) VWS, OFFSET BY WARM (29-30C) SEA SURFACE TEMPERATURES, AND GOOD POLEWARD AND EQUATORWARD OUTFLOW. GLOBAL MODELS ARE IN AGREEMENT THAT TC08S WILL RETROGRADE TO THE EAST AS IT INTERACTS WITH TROPICAL CYCLONE 08S OVER THE NEXT FEW DAYS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 23 TO 25 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1008 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS REMAINS LOW. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 23 TO 25 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1008 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS REMAINS LOW.

Last Updated - 01/17/23 Valid - 01/25/23 - 02/07/23 The Madden-Julian Oscillation (MJO) RMM index indicates a slowed and weakened MJO signal over the western Hemisphere, which appears to be tied to destructively interfering Rossby wave activity over the Americas during the last week. This is also reflected in CPCs velocity potential MJO index revealing a less organized wave-1 pattern throughout the global tropics. Despite this weakening, the leading edge of the enhanced MJO phase has continued to shift eastward, having crossed the Prime Meridian during the past week. Looking ahead, there is increased forecast confidence for a more coherent and potentially robust MJO emerging over the Indian Ocean, which continues to be predicted by several dynamical models during the next two weeks. Beyond this time, several RMM solutions point to a sharp decrease of the intraseasonal signal while continuing to propagate the active phase of the MJO into the Maritime Continent during early February. However, the impact of the removal of the interannual signal (120-day mean) in the RMM computation adds uncertainty. This procedure may be dampening the true MJO signal where its associated convective and circulation pattern becomes more in-phase with La Nina by this time. This potential underestimation of the MJO in RMM space is evidenced by extended range velocity potential forecasts from the GEFS and ECMWF, which show a more coherent wave-1 pattern, with the enhanced envelope maintaining some structure as it shifts eastward across the Maritime Continent and western Pacific later in February. Nonetheless, a potentially robust Indian Ocean MJO event favors increased chances for tropical cyclone (TC) formation in the southwestern portion of the basin, with decreasing chances over the South Pacific later in January. Outside of the tropics, a constructively interfering MJO may reinforce the low frequency La Nina base state and its typical extratropical response over North America, where models are beginning to favor more of a negative Pacific-North America (PNA) pattern taking shape by the end of January and early February. No tropical cyclones formed during the past week, though the Joint Typhoon Warning Center has issued TC formation alerts on a disturbance located in the southern Indian Ocean (96S) and another in South Pacific (91P) with high chances of development in the near-term. For week-2, historical TC genesis composites during Jan-Mar Indian Ocean MJO events (phases 2 and 3) show elevated chances for development over the southwestern portion of the basin, with decreased chances over the waters north of Australia and into the South Pacific. This pattern is consistent with the probabilistic TC guidance during week-2, however there is uncertainty as to how much of these signals are tied to antecedent TC activity during week-1. Regardless, large scale conditions are likely to remain favorable for additional TC formation in this part of the Indian Ocean, which is supported in the latest ensemble and deterministic model guidance. Therefore, moderate chances (40%) for TC development are posted from the Mozambique Channel to the Reunion, with a broad coverage of slight chances (20%) issued extending eastward to approximately 75E. North of the equator, there has been good run-to-run continuity in the GEFS and ECMWF ensembles favoring a broad area of deepening low pressure over the South China and Philippine Seas early in week-2. Although climatology is not particularly favorable for genesis in the northwestern Pacific, there is additional support from probabilistic tools with ensembles favoring stronger anomalous lower-level westerlies to warrant slight chances (20%) being issued in the region.