TC 11S(FREDDY): Super Typhoon intensity//TC 13S(DINGANI) weakening//Invest 91P//Invest 99W//10 day GTHO maps//15/15utc

JTWC IS ISSUING 12HOURLY WARNINGS ON TC 11S(FREDDY) AND TC 13S(DINGANI). 3HOURLY SATELLITE BULLETINS ARE ISSUED ON 11S, 13S AND INVEST 91P.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) AND A 151256Z SSMIS 91GHZ IMAGE DEPICT A VERY WELL ORGANIZED SYSTEM WITH A 13 NM DIAMETER EYE. THERE IS EVIDENCE OF PRESSURE ON THE EASTERN PERIPHERY AS THE SYSTEM IS TRACKING UNDER AN AREA OF WESTWARD UPPER-LEVEL WIND FLOW ESTIMATED AT 35-40 KNOTS. ENVIRONMENTAL ANALYSIS INDICATES TC 11S TO BE IN MARGINALLY FAVORABLE CONDITIONS FOR CONTINUAL TROPICAL DEVELOPMENT. THESE CONDITIONS ARE CHARACTERIZED BY THE AFOREMENTIONED OUTFLOW ALOFT, MODERATE (15-20 KTS) VERTICAL WIND SHEAR (VWS), A VERY STRONG 850 MB VORTICITY SIGNATURE, AND WARM (27-28 C) SEA SURFACE TEMPERATURES (SST). THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE ABOVE MENTIONED MSI AND MICROWAVE IMAGERY. THE INITIAL INTENSITY OF 135 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON A BLEND OF MULTI-AGENCY AND AUTOMATED DVORAK ESTIMATES.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TC FREDDY CONTINUES ITS WESTWARD TRACK AS IT TRANSITS THE NORTHERN PERIPHERY OF THE STR TO THE SOUTH. THE SYSTEM WILL CONTINUE THIS TRAJECTORY UNTIL APPROXIMATELY TAU 36 WHEN IT WILL EXPERIENCE A SLIGHT DIP WEST-SOUTHWESTWARD DUE TO THE SUPPORTING STR MIGRATING TO THE EAST. THERE IS COPIOUS AMOUNTS OF DRY AIR SURROUNDING THE SYSTEM, HOWEVER, TC FREDDY WILL STAY COCOONED IN ITS OWN MOISTURE POCKET DURING ITS FORECAST TRACK. TC 11S IS FORECAST TO SLOWLY BUT SURELY DECREASE IN INTENSITY THROUGHOUT THE FORECAST PERIOD, CONVERSELY, THE SYSTEM HAS UNDERGONE THREE PEAK INTENSITY EVENTS AND THE POSSIBILITY OF A FOURTH EVENT SHOULD NOT BE RULED OUT.

MODEL DISCUSSION: THE JTWC MODEL TRACK CONSENSUS REMAINS IN TIGHT AGREEMENT WITH A GRADUAL SPREAD TO 50 NM AT TAU 48. AFTERWARDS, THE SPREAD INCREASES TO 200 NM BY TAU 120. BECAUSE OF THIS, THE JTWC FORECAST TRACK IS PLACED WITH HIGH CONFIDENCE UP TO TAU 72, THEN MEDIUM CONFIDENCE OUT TO TAU 120. ALL CONSENSUS MEMBERS AGREE ON THE WEST-SOUTHWESTWARD SHIFT IN TRACK AFTER TAU 36. THE INTENSITY GUIDANCE IS ALSO IN GOOD AGREEMENT WITH THE EXCEPTION OF GFS WHICH DECREASES THE INTENSITY WELL BEYOND THE OTHER CONSENSUS MEMBERS. THE JTWC INTENSITY FORECAST IS SET WITH MEDIUM CONFIDENCE UP TO TAU 72, THEN LOW CONFIDENCE THEREAFTER. THIS IS DUE TO THE INCREASE OF INTENSITY OBSERVED OVER THE PAST 12 HOURS.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS AN EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) WITH FRAGMENTED FEEDER BANDS WRAPPING INTO THE CORE. THE SYSTEM HAS BECOME DECOUPLED FROM THE MAIN BULK OF CONVECTION WHICH IS NOW COMPLETELY DISPLACED POLEWARD. A 150508Z ASCAT-B IMAGE SHOWS THE LLCC QUITE WELL, HOWEVER, A MAJORITY OF THE EASTERN PERIPHERY IS NOT VIEWABLE. THIS IMAGE ALSO SHOWS 35 KNOT WINDS DOMINATING IN ALL QUADRANTS WITH THE EXCEPTION OF THE NORTHWEST QUADRANT WHERE 30 KNOT WINDS PREDOMINATELY REIGN. MOREOVER, THERE ARE 40-45 KNOT WIND BARBS NOTED IN THE SOUTHERN PERIPHERY WHICH LENDS TO MEDIUM CONFIDENCE IN THE JTWC INITIAL INTENSITY OF 50 KNOTS. THE INITIAL WIND RADII WAS ALSO ADJUSTED BASED ON THIS ASCAT IMAGE. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THIS ASCAT PASS, AS WELL AS THE AFOREMENTIONED MSI. ENVIRONMENTAL ANALYSIS REVEALS TC DINGANI IS IN AN UNFAVORABLE ENVIRONMENT FOR FURTHER TROPICAL DEVELOPMENT CHARACTERIZED BY VERY LITTLE OUTFLOW ALOFT, STRONG (30-35 KTS) VERTICAL WIND SHEAR (VWS), AND RELATIVELY COOLER (25-26 C) SEA SURFACE TEMPERATURES.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TC DINGANI CONTINUES ITS SOUTH-SOUTHWESTWARD TRACK AS IT IS NOW APPROACHING COOLER WATERS. TC 13S WILL CONTINUE THIS TRAJECTORY AS IT DECREASES IN INTENSITY DUE TO INCREASING VWS, CONTINUAL DRY AIR ENTRAINMENT, AND DECLINING SSTS. BY TAU 24 TC DINGANI WILL BEGIN TO FALL UNDER THE INFLUENCE OF THE SUBTROPICAL JET AND TURN TO A SOUTHEASTWARD TRACK, ALL THE WHILE CONTINUING TO DECREASE IN INTENSITY AND COMPLETELY DISSIPATE BY TAU 48.

MODEL DISCUSSION: THE JTWC MODEL TRACK CONSENSUS REMAINS IN TIGHT AGREEMENT WITH A GRADUAL SPREAD TO 45 NM AT TAU 24. AFTERWARDS, THE SPREAD INCREASES TO 60 NM BY TAU 48. ALL MEMBERS AGREE ON THE SOUTHEASTWARD SHIFT IN TRACK BY TAU 24 AS THE SYSTEM SUCCUMBS TO THE PREVAILING WESTERLIES. THE INTENSITY MODEL GUIDANCE IS ALSO IN TIGHT AGREEMENT WITH ALL MEMBERS SUPPORTIVE OF A DISSIPATION SCENARIO FROM HERE ON OUT. BECAUSE OF THIS, THE JTWC FORECAST TRACK AND FORECAST INTENSITY ARE BOTH SET WITH HIGH CONFIDENCE THROUGHOUT THE FORECAST PERIOD.

THE AREA OF CONVECTION (INVEST 91P) PREVIOUSLY LOCATED NEAR 15.1S 140.4E IS NOW LOCATED NEAR 14.9S 139.5E, APPROXIMATELY 105 NM NORTH-NORTHEAST OF MORNINGTON ISLAND, AUSTRALIA. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY (EIR) AND A 150932Z SSMIS 91GHZ MICROWAVE PASS DEPICT A WEAK AND ELONGATED LOW-LEVEL CIRCULATION (LLC) WITH A RELATIVELY SMALL AREA OF CONVECTION IN THE SOUTHEASTERN PORTION OF THE GULF OF CARPENTARIA. A 151200Z METAR FROM MORNINGTON ISLAND REVEALS WINDS FROM THE SOUTHEAST AT 14KTS. ENVIRONMENTAL ANALYSIS REVEALS THAT INVEST 91P IS IN A MARGINALLY FAVORABLE ENVIRONMENT FOR INTENSIFICATION DUE LOW TO MODERATE (15-20) VWS, MODERATE POLEWARD OUTFLOW ALOFT, AND VERY WARM (29-30C) SST. GLOBAL MODELS GENERALLY AGREE THAT INVEST 91P TRACK IN A SOUTHEASTWARD TRAJECTORY BEFORE RECURVING SOUTHWEST, AND MAKING LANDFALL OVER NORTHERN AUSTRALIA WITHIN THE NEXT 36 HOURS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 20 TO 25 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 998 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS DOWNGRADED TO LOW.

GLOBAL MODELS GENERALLY AGREE THAT INVEST 91P TRACK IN A SOUTHEASTWARD TRAJECTORY BEFORE RECURVING SOUTHWEST, AND MAKING LANDFALL OVER NORTHERN AUSTRALIA WITHIN THE NEXT 36 HOURS.

THE AREA OF CONVECTION (INVEST 99W) PREVIOUSLY LOCATED NEAR 5.3N 134.8E IS NOW LOCATED NEAR 6.0N 134.4E, APPROXIMATELY 80 NM SOUTH OF PALAU. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY (EIR) AND A 150938Z SSMIS 91GHZ MICROWAVE PASS DEPICTS A BROAD CIRCULATION WITH DEEP CONVECTION IN THE NORTHWESTERN SEMICIRCLE. ENVIRONMENTAL ANALYSIS REVEALS THE AREA TO BE UNFAVORABLE FOR 99W TO DEVELOP DUE TO VERY HIGH (30-40KT) VWS AND MINIMAL UPPER LEVEL EXHAUST, OFFSET ONLY BY WARM (28- 29C) SSTS. GLOBAL MODELS ARE IN AGREEMENT THAT 99W WILL CONTINUE ON A NORTH-NORTHWESTERLY TRACK OVER THE NEXT FEW DAYS WITH LITTLE INTENSIFICATION. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 15 TO 20 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1007 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS REMAINS LOW.

Last Updated - 02/14/23 Valid - 02/22/23 - 03/07/23 During the past week, both the RMM and upper-level velocity potential based MJO indices continue to reflect coherent Madden Julian Oscillation (MJO) activity, with the enhanced convective phase having entered the far western Pacific in the past few days. During the next week, there is good agreement in the dynamical models favoring continued eastward propagation of the MJO signal across the western Pacific where it is anticipated to destructively interfere with the low frequency footprint. Notably, time/longitude forecasts of lower-level wind anomalies show a major disruption of an enhanced trade wind regime over the central Pacific tied to La Nina, with anomalous westerlies emerging over the eastern Pacific and velocity potential anomaly fields maintaining a fairly defined wave-1 pattern. As the MJO propagates across the western Hemisphere during week-2, RMM forecasts generally depict a weakening mean signal and increased ensemble spread contributing to added uncertainty later in February. Despite a potentially much less coherent MJO at this lead, the large-scale environment is expected to become less (more) favorable for tropical cyclone (TC) development in the Indian Ocean (South Pacific). The extratropical response associated with western Hemisphere MJO events during boreal winter historically favors warmer (colder) than normal conditions developing across the western (eastern) U.S., but this is at odds with the latest 500-hPa height anomaly guidance from the ensembles which maintain more of a La Nina pattern over North America heading into March. Two TCs formed in the global tropics during the past week. In the South Pacific, TC Gabrielle developed on 2/8 and peaked at category-3 intensity this past weekend over the Coral Sea. Although Garbrielle weakened and lost its tropical characteristics while tracking poleward, this system brought strong winds and heavy precipitation over New Zealand, resulting in extensive power outages, flooding, and damages to infrastructure in the North Island during the past 24 hours. In the southern Indian Ocean, TC Dingani formed on 2/9 near 90E,17S and reached category-1 strength before weakening under an unfavorable shear environment. The Joint Typhoon Warning Center (JTWC) forecasts this system to track southward and dissipate over open waters in the next few days. Since forming on 2/6, TC Freddy remains active in the southern Indian Ocean and is currently located near 90E,15S. After a brief period of weakening this past weekend, the JTWC expects Freddy to strengthen to a category-4 strength system while tracking due west during the next 5 days. Beyond this time, both the GEFS and ECMWF ensembles show Freddy maintaining a westerly track and nearing Madagascar late in week-1 and early in week-2. Regardless of landfall, enhanced precipitation amounts are favored over the southwestern Indian Ocean during week-2 associated with this disturbance. For week-2, probabilistic genesis tools appear fairly muted in regards to TC development across the southern Indian Ocean. The GEFS ensemble continues to feature an area of lowering pressure near 70E early in week-2, however the ECMWF ensemble is less supportive of this realization and there is insufficient confidence for genesis in this part of the basin given the more unfavorable upper-level environment tied to the MJO. Farther east, there is better agreement in the ensembles favoring a broad area of deepening low pressure in the Timor Sea. Given good continuity in the probabilistic guidance, slight chances for genesis are posted to the north of the Kimberley Coast of Australia for week-2. In the South Pacific, a broad area of slight chances for TC development is issued from the Coral Sea to the Fiji Islands with moderate chances (40%) posted to the west of Vanuatu where ensembles and probabilistic tools show the strongest signals for TC formation late in February. The precipitation outlooks for weeks 2 and 3 are based on a historical skill weighted blend of GEFS, CFS, ECMWF and Canadian ensembles, MJO precipitation composites, La Nina conditions, and anticipated TC tracks. For hazardous weather concerns in your area during the next two weeks, please refer to your local NWS office, the Medium Range Hazards Forecast from the Weather Prediction Center (WPC), and CPCs Week-2 Hazard Outlook. Forecasts made over Africa are made in coordination with the International Desk at CPC.