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全球热带气旋监测公报
“梅甘”缓慢向偏南方向移动
时 间：17日08时（北京时）
海 域：澳大利亚附近海域
命 名：“梅甘”，MEGAN
中心位置：南纬14.8度、东经137.4度
强度等级：二级热带气旋
最大风力：11级（30米/秒，相当于我国的强热带风暴级）
中心气压：978百帕
参考位置：澳大利亚昆士兰州汤斯维尔西偏北方向约1120公里的洋面上
变化过程：过去24小时，“梅甘”由10级加强到11级
预报结论：“梅甘”将缓慢向偏南移动，强度将略有增强。
图1 卫星红外监测图像（北京时间2024年03月17日08时00分）
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AXAU01 ADRM 170700 IDD20020 TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - NORTHERN REGION Issued by AUSTRALIAN BUREAU OF METEOROLOGY TROPICAL CYCLONE WARNING CENTRE at: 0700 UTC 17/03/2024 Name: Severe Tropical Cyclone Megan Identifier: 09U Data At: 0600 UTC Latitude: 15.0S Longitude: 137.1E Location Accuracy: within 15nm (30 km) Movement Towards: south southwest (209 deg) Speed of Movement: 4 knots (7 km/h) Maximum 10-Minute Wind: 65 knots (120 km/h) Maximum 3-Second Wind Gust: 90 knots (165 km/h) Central Pressure: 973 hPa Radius of 34-knot winds NE quadrant: 90 nm (165 km) Radius of 34-knot winds SE quadrant: 60 nm (110 km) Radius of 34-knot winds SW quadrant: 60 nm (110 km) Radius of 34-knot winds NW quadrant: 80 nm (150 km) Radius of 48-knot winds NE quadrant: 50 nm (95 km) Radius of 48-knot winds SE quadrant: 40 nm (75 km) Radius of 48-knot winds SW quadrant: 40 nm (75 km) Radius of 48-knot winds NW quadrant: 40 nm (75 km) Radius of 64-knot winds: nm ( km) Radius of Maximum Winds: 20 nm (35 km) Dvorak Intensity Code: T4.5/4.5/D1.5/24HRS STT:D0.5/06HRS Pressure of outermost isobar: 1002 hPa Radius of outermost closed isobar: 200 nm (370 km) FORECAST DATA Date/Time : Location : Loc. Accuracy: Max Wind : Central Pressure (UTC) : degrees : nm (km): knots(km/h): hPa +06: 17/1200: 15.2S 137.0E: 030 (060): 070 (130): 969 +12: 17/1800: 15.4S 137.0E: 045 (080): 075 (140): 965 +18: 18/0000: 15.6S 137.0E: 055 (100): 080 (150): 960 +24: 18/0600: 15.8S 136.9E: 065 (115): 080 (150): 960 +36: 18/1800: 16.1S 136.4E: 085 (155): 050 (095): 984 +48: 19/0600: 16.4S 135.6E: 100 (180): 035 (065): 994 +60: 19/1800: 16.5S 134.4E: 115 (215): 030 (055): 997 +72: 20/0600: 16.4S 133.0E: 130 (235): 025 (045): 999 +96: 21/0600: 16.0S 130.0E: 165 (300): 020 (035): 1000 +120: 22/0600: 15.9S 127.5E: 200 (370): 020 (035): 1001 REMARKS: Severe Tropical Cyclone Megan continues to intensify over the southwestern Gulf of Carpentaria. Banding in the central dense overcast has improved during the day, and a marginal, intermittent eye-like feature has been visible in the IR satellite imagery at times. Confidence in the centre position is good based on satellite imagery plus Gove and Mornington Island radars. Dvorak analysis: DT based on a 3 hour average of curved band patterns with 1.1 to 1.3 wraps. 0.5 added to T number for white or colder bands to give DT4.5. MET is also 4.5 based on a 24 hour D+ trend, however PT is adjusted down to 4.0. FT = CI = 4.5. Objective aids are: ADT 79kt, AiDT 77kt, DPRINT 80kt, DMINT 77kt, SATCON 69kt and MW Sounders 59kt (all 1-min average). Intensity is analysed at 65 knots based on a combination of subjective Dvorak, objective aids, and model guidance. Motion over the past 6 hours has been more to the southwest, although it is possible this is a shorter term trochoidal oscillation, with longer term average motion remaining to the south-southwest. Mid-level ridging to the east and to a lesser extent to the south appear to be the dominant steering influences. This should see the system continue on a slow south-southwest track until it crosses the southwestern Gulf of Carpentaria coast. There remains uncertainty in the timing of this crossing, with guidance spread across the interval from tonight to Tuesday morning. Beyond that, the mid-level ridge to the south is expected to strengthen and steer the system west across inland parts of the Northern Territory as a tropical low through the remainder of the week. Tropical Cyclone Megan has developed against moderate easterly wind shear, currently estimated at around 15-20 knots from CIMSS upper wind analysis. This has been offset by otherwise favourable conditions; abundant low and mid-level moisture, and high SSTs (30-31C) over the Gulf of Carpentaria. 03UTC CIMSS upper winds show good outflow persisting in the southern quadrants, though upper northerlies are beginning to encroach on the northern side of the system due to an upper anticyclone strengthening to the east. The forecast track should move the system further into the lighter shear regime over the next 24 hours, and a standard rate of development is therefore forecast to continue. This would see Megan reach high category 3 intensity prior to forecast landfall on Monday. However this comes with uncertainty. On one hand, a period of rapid intensification cannot be ruled out given the favourable atmospheric conditions along the forecast track. Another scenario, however, is the system moving more quickly and hence moving closer to land earlier, in which case it will have less time to develop and the landfall intensity may be lower. Copyright Commonwealth of Australia == The next bulletin for this system will be issued by: 17/1330 UTC.
Time (ACST) Intensity Category Latitude
(decimal deg.)Longitude
(decimal deg.)Estimated Position
Accuracy (km)0hr 4 pm March 17 3 15.0S 137.1E 30 +6hr 10 pm March 17 3 15.2S 137.0E 60 +12hr 4 am March 18 3 15.4S 137.0E 80 +18hr 10 am March 18 3 15.6S 137.0E 100 +24hr 4 pm March 18 3 15.8S 136.9E 115 +36hr 4 am March 19 2 16.1S 136.4E 155 +48hr 4 pm March 19 tropical low 16.4S 135.6E 180 +60hr 4 am March 20 tropical low 16.5S 134.4E 215 +72hr 4 pm March 20 tropical low 16.4S 133.0E 235 -
全球热带气旋监测公报
“梅甘”加强为三级强热带气旋
时 间：17日14时（北京时）
海 域：澳大利亚附近海域
命 名：“梅甘”，MEGAN
中心位置：南纬15.0度、东经137.1度
强度等级：三级强热带气旋
最大风力：12级（33米/秒，相当于我国的台风级）
中心气压：973百帕
参考位置：澳大利亚昆士兰州汤斯维尔西偏北方向约1140公里的洋面上
变化过程：过去24小时，“梅甘”由10级加强到12级
预报结论：“梅甘”将以每小时5-10公里的速度向南偏西方向缓慢移动，强度还将略有增强。
图1 卫星红外监测图像（北京时间2024年03月17日14时00分）
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WTPS31 PGTW 170900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 19P (MEGAN) WARNING NR 008// RMKS/ 1. TROPICAL CYCLONE 19P (MEGAN) WARNING NR 008 01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 170600Z --- NEAR 15.0S 137.0E MOVEMENT PAST SIX HOURS - 270 DEGREES AT 04 KTS POSITION ACCURATE TO WITHIN 060 NM POSITION BASED ON CENTER LOCATED BY A COMBINATION OF SATELLITE, RADAR AND SYNOPTIC DATA PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 085 KT, GUSTS 105 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 040 NM NORTHEAST QUADRANT 035 NM SOUTHEAST QUADRANT 035 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 060 NM NORTHEAST QUADRANT 045 NM SOUTHEAST QUADRANT 045 NM SOUTHWEST QUADRANT 065 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 090 NM NORTHEAST QUADRANT 080 NM SOUTHEAST QUADRANT 075 NM SOUTHWEST QUADRANT 090 NM NORTHWEST QUADRANT REPEAT POSIT: 15.0S 137.0E --- FORECASTS: 12 HRS, VALID AT: 171800Z --- 15.5S 136.8E MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 000 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 000 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 030 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 100 NM NORTHEAST QUADRANT 080 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 090 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 225 DEG/ 02 KTS --- 24 HRS, VALID AT: 180600Z --- 15.8S 136.5E MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 040 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 000 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 080 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 235 DEG/ 04 KTS --- 36 HRS, VALID AT: 181800Z --- 16.2S 135.9E MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 070 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 250 DEG/ 05 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 190600Z --- 16.5S 135.0E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND VECTOR TO 72 HR POSIT: 265 DEG/ 07 KTS --- 72 HRS, VALID AT: 200600Z --- 16.6S 132.2E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND --- REMARKS: 170900Z POSITION NEAR 15.1S 137.0E. 17MAR24. TROPICAL CYCLONE 19P (MEGAN), LOCATED APPROXIMATELY 386 NM EAST-SOUTHEAST OF DARWIN, AUSTRALIA, HAS TRACKED WESTWARD AT 04 KNOTS OVER THE PAST SIX HOURS. MINIMUM CENTRAL PRESSURE AT 170600Z IS 962 MB. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 170600Z IS 25 FEET. NEXT WARNINGS AT 171500Z, 172100Z, 180300Z AND 180900Z.// NNNN
WDPS31 PGTW 170900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 19P (MEGAN) WARNING NR 008// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 15.0S 137.0E INITIAL INTENSITY: 85 KTS GEOGRAPHIC REFERENCE: 386 NM EAST-SOUTHEAST OF DARWIN, AUSTRALIA MOVEMENT PAST 6 HOURS: WESTWARD AT 04 KTS SIGNIFICANT WAVE HEIGHT: 25 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL CYCLONE (TC) 19P (MEGAN) EXHIBITING A VERY EXPANSIVE CENTRAL DENSE OVERCAST FEATURE OBSCURING NEARLY ALL OF THE GULF OF CARPENTARIA AS WELL AS THE STORMS ASSESSED LOW-LEVEL CIRCULATION CENTER. 170417Z AMSR2 37GHZ AND 89GHZ SATELLITE MICROWAVE IMAGERY AND RADAR DATA REVEALED THE SYSTEM HAS A COMPLETE EYE STRUCTURE THAT IS LIKELY BEING COVERED IN VISIBLE IMAGERY DUE TO THE ROBUST CENTRAL CONVECTION OVER THE PAST SIX HOURS WITH AN ASSESSED POINT SOURCE ALOFT COLLOCATED OVERHEAD THE LLCC. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON EXTRAPOLATION OF THE AFOREMENTIONED AMSR2 SATELLITE MICROWAVE IMAGES AND RADAR DATA. THE INITIAL INTENSITY OF 85 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE RISE OF SUBJECTIVE AND OBJECTIVE INTENSITY ESTIMATES LISTED BELOW. INITIAL WIND RADII BASIS: 170417Z AMSR2 WINDSPEED IMAGE AND SURFACE OBSERVATIONS CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A WEAK NEAR EQUATORIAL RIDGE (NER) TO THE EAST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T4.5 - 77 KTS KNES: T5.0 - 90 KTS CIMSS SATCON: 83 KTS AT 170700Z CIMSS ADT: 82 KTS AT 170730Z CIMSS DPRINT: 83 KTS AT 170600Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 10-15 KTS SST: 30-31 CELSIUS OUTFLOW: MODERATE EQUATORWARD ANALYSIS CONFIDENCE: INITIAL POSITION: MEDIUM INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: MEDIUM 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TC 19P (MEGAN) IS FORECAST TO TRACK SOUTH-SOUTHWESTWARD (TAU 00 TO TAU 12) TO SOUTHWESTWARD (TAU 12 TO 36) FOLLOWING THE STEERING INFLUENCE OF A WEAK NER TO THE EAST. PRIOR TO LANDFALL NEAR TAU 24, A FAVORABLE ENVIRONMENT HAVING LOW (10-15KTS) VERTICAL WIND SHEAR (VWS), VERY WARM (30-31C) SEA SURFACE TEMPERATURES (SST), AND IMPROVING OUTFLOW ALOFT (COLLOCATED WITH UPPER-LEVEL POINT SOURCE) LEAVES ROOM FOR FURTHER INTENSIFICATION TO OCCUR THROUGH TAU 12. ONCE INTERACTION WITH LAND AND FRICTIONAL COMPONENTS BEGIN TO IMPACT THE STORM, A RAPID WEAKENING TREND IS ANTICIPATED TO START NEAR TAU 12 AND CONTINUE THROUGH TAU 72 AS THE SYSTEM TRACKS INLAND. SHORTLY AFTER TAU 36 THE PRIMARY STEERING INFLUENCE IS EXPECTED TO SHIFT FROM THE PREVIOUSLY MENTIONED NER TO A STR OVER CENTRAL AUSTRALIA AND STEER THE SYSTEM WESTWARD THROUGH TAU 72. DISSIPATION IS FORECAST TO BE COMPLETE BY TAU 72 OVER NORTHERN AUSTRALIA. MODEL DISCUSSION: GLOBAL NUMERICAL MODEL GUIDANCE IS IN OVERALL GOOD AGREEMENT OVER THE DURATION OF THE FORECAST INTERVAL, WITH THE MOST SIGNIFICANT UNCERTAINTY BEING TRACK SPEED BETWEEN TAU 00 AND TAU 36. THE CROSS-TRACK SPREAD AMONG JTWC CONSENSUS MEMBERS IS 56NM BETWEEN ECMWF ENSEMBLE MEAN (WESTERN-MOST) AND GALWEM (EASTERN-MOST) BY TAU 36, WITH A HIGHER ALONG TRACK SPREAD OF 102NM BETWEEN GFS (SOUTHERN-MOST) AND GALWEM (NORTHERN-MOST) OVER THE SAME INTERVAL. THE CROSS TRACK SPREAD MORE THAN DOUBLES TO 135NM BY TAU 72. THE INTENSITY FORECAST, LIKELY DUE TO A SLIGHTLY HIGHER THAN ANTICIPATED TRACK SPEED OVER THE PAST 12 HOURS, HAS SHIFTED PEAK INTENSITY TO OCCUR EARLIER IN TIME (TAU 12) THAN PREVIOUSLY FORECAST. STATISTICAL- DYNAMICAL GUIDANCE OVERSHOOTS THE JTWC INTENSITY FORECAST, WHILE MESOSCALE AND GLOBAL MODEL SOLUTIONS COME IN JUST UNDER THE FORECAST. THE OVERALL GOOD AGREEMENT WITH SOME UNCERTAINTY PRESENTED CONTRIBUTES TO THE OVERALL FORECAST CONFIDENCE OF MEDIUM. FORECAST CONFIDENCE: TRACK 0 - 72 HR: MEDIUM INTENSITY 0 - 72 HR: MEDIUM// NNNN
最后于 2024-03-17 18:00:00 被ygsj24编辑 ，原因： -
AXAU01 ADRM 171323 IDD20020 TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - NORTHERN REGION Issued by AUSTRALIAN BUREAU OF METEOROLOGY TROPICAL CYCLONE WARNING CENTRE at: 1323 UTC 17/03/2024 Name: Severe Tropical Cyclone Megan Identifier: 09U Data At: 1200 UTC Latitude: 15.1S Longitude: 137.1E Location Accuracy: within 15nm (30 km) Movement Towards: southwest (224 deg) Speed of Movement: 2 knots (4 km/h) Maximum 10-Minute Wind: 70 knots (130 km/h) Maximum 3-Second Wind Gust: 100 knots (185 km/h) Central Pressure: 967 hPa Radius of 34-knot winds NE quadrant: 90 nm (165 km) Radius of 34-knot winds SE quadrant: 60 nm (110 km) Radius of 34-knot winds SW quadrant: 60 nm (110 km) Radius of 34-knot winds NW quadrant: 80 nm (150 km) Radius of 48-knot winds NE quadrant: 50 nm (95 km) Radius of 48-knot winds SE quadrant: 40 nm (75 km) Radius of 48-knot winds SW quadrant: 40 nm (75 km) Radius of 48-knot winds NW quadrant: 40 nm (75 km) Radius of 64-knot winds: nm ( km) Radius of Maximum Winds: 15 nm (30 km) Dvorak Intensity Code: T4.0/4.5/D0.5/24HRS STT:W0.5/06HRS Pressure of outermost isobar: 1002 hPa Radius of outermost closed isobar: 200 nm (370 km) FORECAST DATA Date/Time : Location : Loc. Accuracy: Max Wind : Central Pressure (UTC) : degrees : nm (km): knots(km/h): hPa +06: 17/1800: 15.3S 137.0E: 030 (055): 075 (140): 965 +12: 18/0000: 15.5S 137.0E: 045 (080): 075 (140): 964 +18: 18/0600: 15.7S 136.9E: 055 (100): 075 (140): 965 +24: 18/1200: 15.8S 136.7E: 065 (120): 065 (120): 973 +36: 19/0000: 16.4S 135.9E: 080 (150): 040 (075): 991 +48: 19/1200: 16.6S 135.0E: 100 (185): 030 (055): 997 +60: 20/0000: 16.7S 133.5E: 115 (210): 025 (045): 999 +72: 20/1200: 16.4S 132.1E: 125 (230): 025 (045): 999 +96: 21/1200: 15.6S 129.0E: 160 (290): 020 (035): 1002 +120: 22/1200: 15.6S 126.3E: 200 (375): 020 (035): 1002 REMARKS: Severe Tropical Cyclone Megan has intensified over the last 6-12 hours and may continue to do so as it approaches the southwest coast of the Gulf of Carpentaria. Confidence in the centre position is good based on satellite imagery and the Mornington Island radar. Intensity is analysed at 70 knots based on a combination of subjective Dvorak and objective aids. Dvorak analysis: with the loss of visible imagery Dvorak analysis has become more difficult and over the last three hours the FT has been biased towards MET/PAT. A trend of S was applied giving a MET of 3.5 with PAT adjusted up to 4.0. FT is 4.0 with CI held at 4.5. Objective aids are: ADT 82kt, AiDT 77 kt, DPRINT 78kt, SATCON 68kt (all 1-min average). Motion over the past 6 hours has been very slowly southwest. Mid-level ridging to the east and to a lesser extent to the south appear to be the dominant steering influences. This should see the system continue on a slow south-southwest track until it crosses the southwestern Gulf of Carpentaria coast. There remains uncertainty in the timing of this crossing, with guidance spread across the interval from Monday morning to Tuesday morning. Beyond that, the mid-level ridge to the south is expected to strengthen and steer the system west across inland parts of the Northern Territory as a tropical low through the remainder of the week. The wind shear near Megan is currently estimated at around 27 knots northeasterly from CIMSS upper wind analysis. The strong wind shear has been offset by otherwise favourable conditions; abundant low and mid-level moisture, and high SSTs (30-31C) over the Gulf of Carpentaria. There has been good outflow in the southern quadrants however the 09UTC CIMSS analyses show poor upper divergence over the system. There is a high degree of uncertainty around the maximum intensity Megan may reach prior to landfall. Model guidance suggests Megan may currently be near peak intensity with nearly all guidance indicating a decreasing trend in maximum wind speeds from 1200 UTC 17 March. However a period of rapid intensification cannot be ruled out with RIPA and FRIA indicating about a 30% chance of intensification of 25 kt over 24 hours. Another scenario, however, is the system moving more quickly and hence moving closer to land earlier, in which case it will have less time to develop and the landfall intensity may be lower. Currently the forecast track increases the intensity to 75 knots over the next 12 hours and then decreases it as the system makes landfall. Once over land Megan should weaken quickly below tropical cyclone strength. Copyright Commonwealth of Australia == The next bulletin for this system will be issued by: 17/1930 UTC.
Time (ACST) Intensity Category Latitude
(decimal deg.)Longitude
(decimal deg.)Estimated Position
Accuracy (km)0hr 10 pm March 17 3 15.1S 137.1E 30 +6hr 4 am March 18 3 15.3S 137.0E 55 +12hr 10 am March 18 3 15.5S 137.0E 80 +18hr 4 pm March 18 3 15.7S 136.9E 100 +24hr 10 pm March 18 3 15.8S 136.7E 120 +36hr 10 am March 19 1 16.4S 135.9E 150 +48hr 10 pm March 19 tropical low 16.6S 135.0E 185 +60hr 10 am March 20 tropical low 16.7S 133.5E 210 +72hr 10 pm March 20 tropical low 16.4S 132.1E 230 -
WTPS31 PGTW 171500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 19P (MEGAN) WARNING NR 009// RMKS/ 1. TROPICAL CYCLONE 19P (MEGAN) WARNING NR 009 01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 171200Z --- NEAR 14.9S 137.3E MOVEMENT PAST SIX HOURS - 070 DEGREES AT 03 KTS POSITION ACCURATE TO WITHIN 060 NM POSITION BASED ON CENTER LOCATED BY A COMBINATION OF SATELLITE, RADAR AND SYNOPTIC DATA PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 095 KT, GUSTS 115 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 035 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 045 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT 045 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 065 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 080 NM NORTHEAST QUADRANT 065 NM SOUTHEAST QUADRANT 075 NM SOUTHWEST QUADRANT 080 NM NORTHWEST QUADRANT REPEAT POSIT: 14.9S 137.3E --- FORECASTS: 12 HRS, VALID AT: 180000Z --- 15.4S 137.1E MAX SUSTAINED WINDS - 085 KT, GUSTS 105 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 020 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 000 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 030 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 090 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 080 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 225 DEG/ 03 KTS --- 24 HRS, VALID AT: 181200Z --- 15.8S 136.7E MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 040 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 000 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 060 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 235 DEG/ 05 KTS --- 36 HRS, VALID AT: 190000Z --- 16.3S 135.9E MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT 000 NM SOUTHEAST QUADRANT 000 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 070 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 260 DEG/ 05 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 191200Z --- 16.5S 134.9E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND VECTOR TO 72 HR POSIT: 275 DEG/ 07 KTS --- 72 HRS, VALID AT: 201200Z --- 16.3S 132.0E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND --- REMARKS: 171500Z POSITION NEAR 15.0S 137.3E. 17MAR24. TROPICAL CYCLONE 19P (MEGAN), LOCATED APPROXIMATELY 400 NM EAST-SOUTHEAST OF DARWIN, AUSTRALIA, HAS TRACKED EAST- NORTHEASTWARD AT 03 KNOTS OVER THE PAST SIX HOURS. MINIMUM CENTRAL PRESSURE AT 171200Z IS 957 MB. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 171200Z IS 29 FEET. NEXT WARNINGS AT 172100Z, 180300Z, 180900Z AND 181500Z.// NNNN
WDPS31 PGTW 171500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 19P (MEGAN) WARNING NR 009// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 14.9S 137.3E INITIAL INTENSITY: 95 KTS GEOGRAPHIC REFERENCE: 400 NM EAST-SOUTHEAST OF DARWIN, AUSTRALIA MOVEMENT PAST 6 HOURS: EAST-NORTHEASTWARD AT 03 KTS SIGNIFICANT WAVE HEIGHT: 29 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL CYCLONE (TC) 19P (MEGAN) EXHIBITING TROCHOIDAL MOTION AS THE SYSTEM TRACKED GENERALLY EAST-NORTHEASTWARD OVER THE PAST SIX HOURS, BACKTRACKING OVER PREVIOUSLY TRAVELED WATERS. A 170844Z SSMIS 37GHZ SATELLITE MICROWAVE IMAGE CAPTURED A WELL-DEFINED MICROWAVE EYE, WITH THE CORRESPONDING 89GHZ IMAGE SUGGESTING THE TC VORTEX IS WELL ALIGNED VERTICALLY. A RCM-3 SYNTHETIC APERTURE RADAR (SAR) IMAGE OF 170919Z REPORTED UP TO 123KTS IN THE NORTHWEST QUADRANT OF THE SYSTEM AND AS LOW AS 92KTS IN THE SOUTHWEST QUADRANT. HOWEVER, A 45 DEGREE INCIDENCE ANGLE TO THE COLLECTING SENSOR MAY HAVE POSITIVELY SKEWED REPORTED VALUES. THE INITIAL POSITION AND INTENSITY OF 95 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE AFOREMENTIONED SAR IMAGE AND THE SUBJECTIVE AND OBJECTIVE INTENSITY ESTIMATES LISTED BELOW. INITIAL WIND RADII BASIS: SAR DATA CURRENT STEERING MECHANISM: WEAK NER EXTENSION TO THE NORTHEAST AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T5.0 - 90 KTS KNES: T5.0 - 90 KTS CIMSS ADT: 82 KTS AT 171200Z CIMSS AIDT: 78 KTS AT 171200Z CIMSS DPRINT: 78 KTS AT 171200Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 15-20 KTS SST: 30-31 CELSIUS OUTFLOW: MODERATE POLEWARD ANALYSIS CONFIDENCE: INITIAL POSITION: MEDIUM INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: MEDIUM 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TC 19P (MEGAN) IS FORECAST TO TRACK SOUTH-SOUTHWESTWARD (TAU 00 TO TAU 12) TO SOUTHWESTWARD (TAU 12 TO 36) FOLLOWING THE STEERING INFLUENCE OF A WEAK NER TO THE NORTHEAST. PRIOR TO LANDFALL NEAR TAU 24, A FAVORABLE ENVIRONMENT HAVING LOW TO MODERATE (10-20KTS) VERTICAL WIND SHEAR (VWS), VERY WARM (30-31C) SEA SURFACE TEMPERATURES (SST), AND MODERATE POLEWARD OUTFLOW ALOFT (COLLOCATED WITH UPPER-LEVEL POINT SOURCE) LEAVES ROOM FOR FURTHER INTENSIFICATION TO OCCUR THROUGH TAU 06. ONCE INTERACTION WITH LAND AND FRICTIONAL COMPONENTS BEGIN TO IMPACT THE STORM, A RAPID WEAKENING TREND IS ANTICIPATED TO START AT OR PRIOR TO TAU 06 AND CONTINUE THROUGH TAU 72 AS THE SYSTEM TRACKS INLAND. SHORTLY AFTER TAU 36 THE PRIMARY STEERING INFLUENCE IS EXPECTED TO SHIFT FROM THE PREVIOUSLY MENTIONED NER TO A STR OVER CENTRAL AUSTRALIA AND STEER THE SYSTEM WESTWARD THROUGH TAU 72. DISSIPATION IS FORECAST TO BE COMPLETE BY TAU 72 OVER NORTHERN AUSTRALIA. MODEL DISCUSSION: GLOBAL NUMERICAL MODEL GUIDANCE IS IN OVERALL GOOD AGREEMENT OVER THE DURATION OF THE FORECAST INTERVAL, WITH THE MOST SIGNIFICANT UNCERTAINTY BEING TRACK SPEED BETWEEN TAU 00 AND TAU 36. DISREGARDING NAVGEM TRACKING WESTWARD FROM TAU 00 TO TAU 72, THE CROSS-TRACK SPREAD AMONG JTWC CONSENSUS MEMBERS IS 71NM BY TAU 36, WITH A HIGHER ALONG TRACK SPREAD OF 93NM OVER THE SAME INTERVAL. BY TAU 72, THE CROSS-TRACK SPREAD BETWEEN ALL JTWC CONSENSUS MEMBERS IS 109NM. OVERALL, INTENSITY GUIDANCE SUGGESTS TC 19P HAS OR WILL REACH PEAK INTENSITY BY TAU 06 WITH A DOWNTREND AND WEAKENING THEREAFTER TO TAU 72. STATISTICAL-DYNAMICAL GUIDANCE (SHIPS) IS THE ONLY OUTLIER AMONG INTENSITY CONSENSUS MEMBERS, AND SOLELY SUGGESTS A CONTINUED INTENSIFICATION PERIOD THROUGH TAU 12, FOLLOWED BY A DOWNTREND TO TAU 72. THE OVERALL GOOD AGREEMENT WITH SOME UNCERTAINTY PRESENTED CONTRIBUTES TO THE OVERALL FORECAST CONFIDENCE OF MEDIUM. FORECAST CONFIDENCE: TRACK 0 - 72 HR: MEDIUM INTENSITY 0 - 72 HR: MEDIUM// NNNN
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AXAU01 ADRM 171901 IDD20020 TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - NORTHERN REGION Issued by AUSTRALIAN BUREAU OF METEOROLOGY TROPICAL CYCLONE WARNING CENTRE at: 1901 UTC 17/03/2024 Name: Severe Tropical Cyclone Megan Identifier: 09U Data At: 1800 UTC Latitude: 15.2S Longitude: 137.2E Location Accuracy: within 15nm (30 km) Movement Towards: south southwest (198 deg) Speed of Movement: 2 knots (3 km/h) Maximum 10-Minute Wind: 70 knots (130 km/h) Maximum 3-Second Wind Gust: 100 knots (185 km/h) Central Pressure: 970 hPa Radius of 34-knot winds NE quadrant: 90 nm (165 km) Radius of 34-knot winds SE quadrant: 70 nm (130 km) Radius of 34-knot winds SW quadrant: 60 nm (110 km) Radius of 34-knot winds NW quadrant: 90 nm (165 km) Radius of 48-knot winds NE quadrant: 50 nm (95 km) Radius of 48-knot winds SE quadrant: 40 nm (75 km) Radius of 48-knot winds SW quadrant: 40 nm (75 km) Radius of 48-knot winds NW quadrant: 50 nm (95 km) Radius of 64-knot winds: 30 nm (55 km) Radius of Maximum Winds: 15 nm (30 km) Dvorak Intensity Code: T4.0/4.5/S0.0/24HRS STT: S0.0/06HRS Pressure of outermost isobar: 1002 hPa Radius of outermost closed isobar: 200 nm (370 km) FORECAST DATA Date/Time : Location : Loc. Accuracy: Max Wind : Central Pressure (UTC) : degrees : nm (km): knots(km/h): hPa +06: 18/0000: 15.6S 137.1E: 035 (065): 075 (140): 967 +12: 18/0600: 15.8S 137.1E: 050 (090): 070 (130): 969 +18: 18/1200: 16.0S 136.9E: 060 (110): 060 (110): 983 +24: 18/1800: 16.3S 136.6E: 070 (125): 050 (095): 988 +36: 19/0600: 16.8S 135.8E: 080 (150): 030 (055): 1000 +48: 19/1800: 16.9S 134.7E: 095 (180): 025 (045): 1001 +60: 20/0600: 16.7S 133.3E: 115 (215): 025 (045): 1000 +72: 20/1800: 16.4S 131.6E: 135 (250): 025 (045): 1000 +96: 21/1800: 15.6S 128.9E: 170 (320): 020 (035): 1001 +120: 22/1800: 15.7S 126.2E: 215 (395): 020 (035): 1002 REMARKS: Severe Tropical Cyclone Megan remains at category 3 intensity while slowly tracking towards the southwestern Gulf of Carpentaria coast. Confidence in the centre position is good based on Mornington Island radar imagery. Intensity is analysed at 70 knots based on a combination of subjective Dvorak and objective aids. Dvorak analysis: an embedded centre pattern with a white or colder surrounding grey shade has been applied in the last few hours, giving a DT of 5.0. A trend of S was applied giving a MET of 3.5 with PAT adjusted up to 4.0. FT is 4.0 with CI held at 4.5. Objective aids are: ADT 82kt, AiDT 84 kt, DPRINT 86kt, SATCON 78kt (all 1-min average). Motion has been near stationary for most of the night, though in the last few hours the system appears to have started tracking towards the south southwest in the direction of the southwestern Gulf of Carpentaria coast. Mid-level ridging to the east and to a lesser extent to the south appear to be the dominant steering influences. This should see the system continue on a slow south-southwest track until it crosses the southwestern Gulf of Carpentaria coast later today. Beyond that, the mid-level ridge to the south is expected to strengthen and steer the system west across inland parts of the Northern Territory as a tropical low through the remainder of the week. The wind shear near Megan is currently northeasterly at around 20 to 25 knots from CIMSS upper wind analysis. The strong wind shear has been offset by otherwise favourable conditions; abundant low and mid-level moisture, good poleward outflow and high SSTs (30-31C) over the Gulf of Carpentaria. Model guidance suggests Megan may currently be near peak intensity with nearly all guidance indicating a decreasing trend in maximum wind speeds. The current forecast scenario sees a slight intensification in the system before landfall, though this equally may not occur given its near steady development overnight and limited amount of time before it crosses the coast. Once over land, Megan should weaken quickly below tropical cyclone strength. Copyright Commonwealth of Australia == The next bulletin for this system will be issued by: 18/0130 UTC.
Time (ACST) Intensity Category Latitude
(decimal deg.)Longitude
(decimal deg.)Estimated Position
Accuracy (km)0hr 4 am March 18 3 15.2S 137.2E 30 +6hr 10 am March 18 3 15.6S 137.1E 65 +12hr 4 pm March 18 3 15.8S 137.1E 90 +18hr 10 pm March 18 2 16.0S 136.9E 110 +24hr 4 am March 19 2 16.3S 136.6E 125 +36hr 4 pm March 19 tropical low 16.8S 135.8E 150 +48hr 4 am March 20 tropical low 16.9S 134.7E 180 +60hr 4 pm March 20 tropical low 16.7S 133.3E 215 +72hr 4 am March 21 tropical low 16.4S 131.6E 250 -
WTPS31 PGTW 172100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 19P (MEGAN) WARNING NR 010// RMKS/ 1. TROPICAL CYCLONE 19P (MEGAN) WARNING NR 010 01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 171800Z --- NEAR 15.4S 137.2E MOVEMENT PAST SIX HOURS - 200 DEGREES AT 05 KTS POSITION ACCURATE TO WITHIN 040 NM POSITION BASED ON EYE FIXED BY A COMBINATION OF SATELLITE AND RADAR PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 035 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT 045 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 055 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 080 NM NORTHEAST QUADRANT 065 NM SOUTHEAST QUADRANT 045 NM SOUTHWEST QUADRANT 080 NM NORTHWEST QUADRANT REPEAT POSIT: 15.4S 137.2E --- FORECASTS: 12 HRS, VALID AT: 180600Z --- 15.9S 136.9E MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 035 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 060 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 090 NM NORTHEAST QUADRANT 080 NM SOUTHEAST QUADRANT 070 NM SOUTHWEST QUADRANT 090 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 230 DEG/ 03 KTS --- 24 HRS, VALID AT: 181800Z --- 16.3S 136.4E MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND RADIUS OF 064 KT WINDS - 015 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 015 NM SOUTHWEST QUADRANT 010 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 070 NM NORTHEAST QUADRANT 070 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 250 DEG/ 05 KTS --- 36 HRS, VALID AT: 190600Z --- 16.6S 135.5E MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND VECTOR TO 48 HR POSIT: 260 DEG/ 06 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 191800Z --- 16.8S 134.3E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND VECTOR TO 72 HR POSIT: 275 DEG/ 07 KTS --- 72 HRS, VALID AT: 201800Z --- 16.6S 131.3E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND --- REMARKS: 172100Z POSITION NEAR 15.5S 137.1E. 17MAR24. TROPICAL CYCLONE 19P (MEGAN), LOCATED APPROXIMATELY 406 NM EAST-SOUTHEAST OF DARWIN, AUSTRALIA, HAS TRACKED SOUTH SOUTHWESTWARD AT 05 KNOTS OVER THE PAST SIX HOURS. MINIMUM CENTRAL PRESSURE AT 171800Z IS 961 MB. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 171800Z IS 27 FEET. NEXT WARNINGS AT 180300Z, 180900Z, 181500Z AND 182100Z. // NNNN
WDPS31 PGTW 172100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 19P (MEGAN) WARNING NR 010// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 15.4S 137.2E INITIAL INTENSITY: 90 KTS GEOGRAPHIC REFERENCE: 406 NM EAST-SOUTHEAST OF DARWIN, AUSTRALIA MOVEMENT PAST 6 HOURS: SOUTH-SOUTHWESTWARD AT 05 KTS SIGNIFICANT WAVE HEIGHT: 27 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: TROPICAL CYCLONE (TC) 19P (MEGAN) HAS CONTINUED TO INTENSIFY OVERNIGHT, AS IT APPROACHES THE SOUTHWESTERN COAST OF THE GULF OF CARPENTARIA. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY, A SERIES OF MICROWAVE IMAGES AND A 170919Z RCM-3 SAR PASS SHOWED THAT TC 19P HAS REMAINED QUASI-STATIONARY OVER THE PAST 12 HOURS, PERFORMING A CLOCKWISE PIROUETTE, AS IT SLOWLY MEANDERED IN A WEAK STEERING PATTERN. A 171642Z ATMS 88.2GHZ MICROWAVE IMAGE REVEALED THAT THE SYSTEM HAS NOW STARTED TO MOVE SOUTH-SOUTHWEST AT ABOUT 5 KNOTS AS THE NER TO THE NORTHEAST HAS STRENGTHENED A BIT. ADDITIONALLY, THE ATMS IMAGERY SHOWED A WEAK MICROWAVE EYE, WITH DEEP CONVECTION PRIMARILY LIMITED TO THE WESTERN HEMISPHERE OF THE CORE. THE MICROWAVE EYE FEATURE LINED UP WELL WITH BOTH THE AGENCY FIX POSITIONS AND THE EYE FEATURE SEEN IN ANIMATED RADAR DATA FROM MORNINGTON ISLAND, PROVIDING HIGH CONFIDENCE TO THE INITIAL POSITION. IN-DEPTH ANALYSIS OF THE EARLIER SAR PASS, SUPPORTS THE 1200Z INTENSITY ESTIMATE OF 95 KNOTS, EVEN THOUGH THE SAR INDICATED WINDS AS HIGH AS 123 KNOTS IN THE NORTHERN PORTION OF THE CIRCULATION. THESE HIGHER WINDS ARE DEEMED AS NOT REPRESENTATIVE AND LIKELY DUE TO TRANSIENT MESOSCALE EFFECTS. REGARDLESS, THE INITIAL INTENSITY AT 1800Z IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE CONGRUENCE OF THE BULK OF OBJECTIVE AND SUBJECTIVE FIX ESTIMATES BELOW. WHILE THE OVERALL ENVIRONMENT REMAINS FAVORABLE, DEEP-LAYER AND MID-LEVEL SHEAR HAVE STARTED TO PICK UP SHARPLY OVER THE PAST 6 TO 12 HOURS AS DEPICTED IN THE MODEL SOUNDING DATA. ANIMATED WATER VAPOR IMAGERY ALSO SUPPORTS AN INCREASED NORTHEASTERLY SHEAR VECTOR, WITH THE PULSING CONVECTION FAILING TO PUSH OUTFLOW AS FAR EASTWARD AS WAS SEEN YESTERDAY. OTHER ENVIRONMENTAL PARAMETERS REMAIN FAVORABLE. INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: SOUTHWESTERN PERIPHERY OF A MID-LEVEL NER TO THE NORTHEAST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T5.0 - 90 KTS KNES: T5.0 - 90 KTS ADRM: T4.5 - 77 KTS CIMSS SATCON: 91 KTS AT 171800Z CIMSS ADT: 82 KTS AT 171800Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 15-20 KTS SST: 30-31 CELSIUS OUTFLOW: MODERATE POLEWARD ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: HIGH INITIAL WIND RADII: MEDIUM 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TC 19P IS EXPECTED TO CONTINUE TRACK SOUTH-SOUTHWEST ALONG THE WESTERN SID OF THE NER CENTERED TO THE NORTHEAST. TRACK SPEEDS ARE EXPECTED TO ROUGHLY MAINTAIN THE PACE OF ADVANCE, THOUGH SOME SLOWING CANNOT BE RULED OUT AS THE LLCC TRACKS OVER THE SIR EDWARD PELLEW GROUP. LANDFALL ON THE MAINLAND COAST IS EXPECTED NEAR TAU 12. AFTER LANDFALL, THE SYSTEM WILL SLOWLY TRACK OVER TO A SOUTHWESTWARD THEN WESTWARD TRACK AS IT COMES UNDER THE STEERING INFLUENCE OF A BUILDING RIDGE TO THE SOUTH. TC 19P LIKELY PEAKED OUT AT 95-100 KNOTS AROUND 0900Z, PER THE SAR IMAGERY, AND IS NOW STARTING TO WEAKEN SLOWLY, AS IT STARTS TO FEEL THE EFFECTS OF THE STEADILY INCREASING NORTHEASTERLY SHEAR, PARTICULARLY IN THE SUB-OUTFLOW LEVELS. HOWEVER, THE WIND FIELD WILL NOT REACT IMMEDIATELY TO THE DESTRUCTION OF THE VORTEX, THUS THE SYSTEM IS FORECAST TO MAINTAIN 90 KNOTS INTENSITY UP THROUGH LANDFALL. ONCE ASHORE HOWEVER, FRICTIONAL EFFECTS, DRY AIR ENTRAINMENT AND A FURTHER INCREASE IN SHEAR WILL COMBINE TO RAPIDLY WEAKEN TC 19P. FULL DISSIPATION IS ANTICIPATED NO LATER THAN TAU 72 AND POTENTIALLY AS EARLY AS TAU 48. MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE IS IN VERY GOOD AGREEMENT THROUGH THE DURATION OF THE FORECAST, WITH MINIMAL SPREAD IN THE CONSENSUS MEMBERS. THE JTWC FORECAST IS PLACED ALONG THE NORTHERN EDGE OF THE GUIDANCE PACKAGE WITH HIGH CONFIDENCE. INTENSITY GUIDANCE IS ALSO IN GOOD AGREEMENT, WITH NEARLY ALL OF THE CONSENSUS MEMBERS SHOWING RAPID WEAKENING FROM THE TAU 00, REACHING 30 KNOTS BETWEEN TAU 48 AND TAU 72. THE ONLY EXCEPTION IS THE GFS VERSION OF SHIPS, WHICH SHOWS THE SYSTEM MAINTAINING CURRENT INTENSITY THROUGH TAU 12, THEN FOLLOWING THE REST OF THE PACK THROUGH TAU 72. THE JTWC FORECAST FOLLOWS THE SHIPS GUIDANCE WITH MEDIUM CONFIDENCE. FORECAST CONFIDENCE: TRACK 0 - 72 HR: HIGH INTENSITY 0 - 72 HR: MEDIUM// NNNN
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AXAU01 ADRM 180156 IDD20020 TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - NORTHERN REGION Issued by AUSTRALIAN BUREAU OF METEOROLOGY TROPICAL CYCLONE WARNING CENTRE at: 0156 UTC 18/03/2024 Name: Severe Tropical Cyclone Megan Identifier: 09U Data At: 0000 UTC Latitude: 15.7S Longitude: 137.1E Location Accuracy: within 15nm (30 km) Movement Towards: south (190 deg) Speed of Movement: 3 knots (5 km/h) Maximum 10-Minute Wind: 75 knots (140 km/h) Maximum 3-Second Wind Gust: 105 knots (195 km/h) Central Pressure: 970 hPa Radius of 34-knot winds NE quadrant: 90 nm (165 km) Radius of 34-knot winds SE quadrant: 60 nm (110 km) Radius of 34-knot winds SW quadrant: 40 nm (75 km) Radius of 34-knot winds NW quadrant: 70 nm (130 km) Radius of 48-knot winds NE quadrant: 45 nm (85 km) Radius of 48-knot winds SE quadrant: 25 nm (45 km) Radius of 48-knot winds SW quadrant: 25 nm (45 km) Radius of 48-knot winds NW quadrant: 45 nm (85 km) Radius of 64-knot winds: 30 nm (55 km) Radius of Maximum Winds: 15 nm (25 km) Dvorak Intensity Code: T4.5/4.5/D0.5/24HRS STT:D0.5/06HRS Pressure of outermost isobar: 1004 hPa Radius of outermost closed isobar: 220 nm (405 km) FORECAST DATA Date/Time : Location : Loc. Accuracy: Max Wind : Central Pressure (UTC) : degrees : nm (km): knots(km/h): hPa +06: 18/0600: 15.9S 136.9E: 030 (055): 070 (130): 969 +12: 18/1200: 16.2S 136.7E: 045 (085): 060 (110): 977 +18: 18/1800: 16.5S 136.4E: 055 (100): 045 (085): 988 +24: 19/0000: 16.8S 136.1E: 065 (120): 035 (065): 992 +36: 19/1200: 17.2S 135.0E: 070 (135): 030 (055): 995 +48: 20/0000: 17.1S 133.5E: 090 (165): 025 (045): 998 +60: 20/1200: 16.9S 131.9E: 115 (210): 025 (045): 1000 +72: 21/0000: 16.6S 130.1E: 135 (250): 025 (045): 1001 +96: 22/0000: 16.3S 127.2E: 170 (315): 020 (035): 1002 +120: 23/0000: 16.2S 125.1E: 220 (405): 020 (035): 1001 REMARKS: Severe Tropical Cyclone Megan at category 3 (75kn) intensity to cross the southwestern Gulf of Carpentaria coast within 3-9 hours. Position based on a combination of Mornington Is radar (edge), visible imagery, Centre Is observations and earlier SAR pass with high confidence noting some offset from shear consideration and an eye is yet to emerge. Intensity is analysed at 75 knots based on the range of inputs: subjective Dvorak, objective aids, SAR imagery and surface observations. Centre Island is now experiencing the southwestern eye wall and winds have been consistent 50kn since 21UTC and pressure now 982hPa; SAR imagery at 2037UTC has higher winds - 90kn in northern quadrants and 70kn in southern quadrants. Dvorak analysis: DT=5.0 from embedded centre pattern in white; MET=4.0 based on Steady 24h trend adjusted to 4.5. FT/CI=4.5. Objective aids are: SATCON 90kn, ADT 67kn, AiDT 74 kn, DPRINT 65kn (all 1-min average). Wind structure based upon many inputs: SAR, ASCAT, HSCAT, SMAP and SMOS, and supported by observations. Motion has been slowly to the south southwest and will make landfall on the southwestern Gulf of Carpentaria coast today. Mid-level ridging to the east and to a lesser extent to the south appear to be the dominant steering influences. From Tuesday the mid-level ridge to the south is expected to strengthen and steer the system west across inland parts of the Northern Territory as a tropical low through the remainder of the week. Slow development has occurred despite the ongoing northeasterly wind shear (CIMSS 22 kn), but otherwise favourable conditions; abundant low and mid-level moisture, good poleward outflow and high SSTs (30-31C). Once over land Megan should weaken quickly and be below tropical cyclone 24h later. Heavy rainfall will accompany the low as it tracks over the NOrthern Territory in the following days. At this stage reintensification over water is not expected in the next 7 days. Copyright Commonwealth of Australia == The next bulletin for this system will be issued by: 18/0730 UTC.
Time (ACST) Intensity Category Latitude
(decimal deg.)Longitude
(decimal deg.)Estimated Position
Accuracy (km)0hr 10 am March 18 3 15.7S 137.1E 30 +6hr 4 pm March 18 3 15.9S 136.9E 55 +12hr 10 pm March 18 2 16.2S 136.7E 85 +18hr 4 am March 19 1 16.5S 136.4E 100 +24hr 10 am March 19 tropical low 16.8S 136.1E 120 +36hr 10 pm March 19 tropical low 17.2S 135.0E 135 +48hr 10 am March 20 tropical low 17.1S 133.5E 165 +60hr 10 pm March 20 tropical low 16.9S 131.9E 210 +72hr 10 am March 21 tropical low 16.6S 130.1E 250 -
WTPS31 PGTW 180300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 19P (MEGAN) WARNING NR 011// RMKS/ 1. TROPICAL CYCLONE 19P (MEGAN) WARNING NR 011 01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 180000Z --- NEAR 15.6S 137.0E MOVEMENT PAST SIX HOURS - 225 DEGREES AT 04 KTS POSITION ACCURATE TO WITHIN 040 NM POSITION BASED ON CENTER LOCATED BY A COMBINATION OF SATELLITE AND RADAR PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 085 KT, GUSTS 105 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 035 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT 045 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 055 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 080 NM NORTHEAST QUADRANT 065 NM SOUTHEAST QUADRANT 035 NM SOUTHWEST QUADRANT 080 NM NORTHWEST QUADRANT REPEAT POSIT: 15.6S 137.0E --- FORECASTS: 12 HRS, VALID AT: 181200Z --- 16.2S 136.4E MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND RADIUS OF 064 KT WINDS - 020 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 010 NM SOUTHWEST QUADRANT 020 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 070 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 230 DEG/ 04 KTS --- 24 HRS, VALID AT: 190000Z --- 16.7S 135.8E MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND VECTOR TO 36 HR POSIT: 245 DEG/ 05 KTS --- 36 HRS, VALID AT: 191200Z --- 17.1S 134.8E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND VECTOR TO 48 HR POSIT: 265 DEG/ 06 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 200000Z --- 17.2S 133.5E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND --- REMARKS: 180300Z POSITION NEAR 15.8S 136.8E. 18MAR24. TROPICAL CYCLONE 19P (MEGAN), LOCATED APPROXIMATELY 401 NM EAST-SOUTHEAST OF DARWIN, AUSTRALIA, HAS TRACKED SOUTHWESTWARD AT 04 KNOTS OVER THE PAST SIX HOURS. MINIMUM CENTRAL PRESSURE AT 180000Z IS 964 MB. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 180000Z IS 24 FEET. NEXT WARNINGS AT 180900Z, 181500Z, 182100Z AND 190300Z. // NNNN
WDPS31 PGTW 180300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 19P (MEGAN) WARNING NR 011// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 15.6S 137.0E INITIAL INTENSITY: 85 KTS GEOGRAPHIC REFERENCE: 401 NM EAST-SOUTHEAST OF DARWIN, AUSTRALIA MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 04 KTS SIGNIFICANT WAVE HEIGHT: 24 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: TROPICAL CYCLONE (TC) 19P (MEGAN) IS IN THE PROCESS OF MAKING LANDFALL OVER NORTH ISLAND AND MOVING DOWN OVER CENTRE ISLAND AT ANALYSIS TIME. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A WEAKENING CENTRAL DENSE OVERCAST (CDO) FEATURE, WITH WARMING CLOUD TOPS, WHICH IS BEING ERODED ON THE EAST SIDE DUE TO PERSISTENT AND STRENGTHENING EASTERLY SHEAR. THE INITIAL POSITION WAS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE AGENCY FIX POSITIONS, ANIMATED RADAR DATA FROM THE MORNINGTON ISLAND RADAR, AND EXTRAPOLATION OF WELL-DEFINED EYE IN A 172027Z RCM-2 SAR NORMALIZED RADAR CROSS SECTION (NRCS) IMAGE. THE INITIAL INTENSITY IS SET AT 85 KNOTS WITH MEDIUM CONFIDENCE, BASED ON AN AVERAGE OF THE SUBJECTIVE AGENCY FIXES, AND IN LIGHT OF THE RAPIDLY DECREASING ADT, AIDT AND DPRINT ESTIMATES AS WELL AS THE OVERALL DEGRADATION IN THE STRUCTURE. SURFACE OBSERVATIONS FROM CENTRE ISLAND SHOW A PEAK SUSTAINED 10MIN WIND OF 52 KTS, WITH GUSTS AS HIGH AS 68 KTS, WITH THE LOWEST PRESSURE READING THUS FAR OF 981MB. THE SAR IMAGERY SHOWED THE HIGHEST WINDS WERE LOCATED TO THE NORTH-NORTHEAST OF THE LOW LEVEL CIRCULATION CENTER (LLCC), AND THUS WINDS AT CENTRE ISLAND LIKELY WILL BE AT THEIR HIGHEST AFTER THE STORM PASSES. ANALYSIS REVEALS A MARGINALLY FAVORABLE NOW THAT THE SYSTEM IS MOVING INLAND. EASTERLY SHEAR IS QUICKLY INCREASING ALONG WITH THE ENTRAINMENT OF DRY AIR OFF THE CONTINENT, LEADING TO A RAPIDLY DETERIORATING ENVIRONMENT. INITIAL WIND RADII BASIS: SAR DATA CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A MID-LEVEL NEAR EQUATORIAL RIDGE (NER) TO THE NORTHEAST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T5.0 - 90 KTS ADRM: T4.5 - 77 KTS CIMSS ADT: 67 KTS AT 172330Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE VWS: 15-20 KTS SST: 30-31 CELSIUS OUTFLOW: MODERATE POLEWARD ANALYSIS CONFIDENCE: INITIAL POSITION: MEDIUM INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: HIGH 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TC 19P WILL MAKE LANDFALL ON THE MAINLAND COAST OF AUSTRALIA WITHIN THE NEXT COUPLE OF HOURS, AFTER PASSING JUST EAST OR DIRECTLY OVER CENTRE ISLAND THEN MOVING ASHORE IN THE MCARTHUR RIVER DELTA REGION. THE SYSTEM WILL CONTINUE INLAND, PASSING CLOSE ABOARD TO BORROLOOLA, BEFORE QUICKLY MOVING FURTHER INLAND ALONG THE NORTHERN SIDE OF A BUILDING RIDGE TO THE SOUTH. ADDITIONAL ANALYSIS OF THE 172027Z SAR PASS SUGGESTS THAT TC 19P REACHED 100 KNOTS INTENSITY AS EARLY AS 1200Z AND THEN MAINTAINED THAT INTENSITY FOR AT LEAST EIGHT HOURS AND THE 1200Z AND 1800Z INTENSITY ESTIMATES HAVE BEEN UPDATED ACCORDINGLY. HOWEVER, THE RAPID INCREASE IN NORTHEASTERLY SHEAR, AND INGESTION OF RELATIVELY DRY LOW-LEVEL AIR FROM THE CONTINENT INTO THE CORE OF THE SYSTEM LED TO A FAIRLY QUICK DROP-OFF IN INTENSITY UP TO THE CURRENT ANALYSIS TIME. SHEAR AND DRY AIR WILL ONLY GET WORSE MOVING FORWARD AND THE SYSTEM IS FORECAST TO UNDERGO RAPID WEAKENING AS IT MOVES FURTHER INLAND. DISSIPATION BELOW THE 35 KNOT WARNING THRESHOLD IS EXPECTED NO LATER THAN TAU 48. MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE IS IN VERY GOOD AGREEMENT ON THE TRACK SCENARIO, WITH LITTLE IN THE WAY OF CROSS-TRACK SPREAD THROUGH THE FORECAST PERIOD. ALONG-TRACK SPREAD HAS ALSO LESSENED SINCE THE PREVIOUS RUN. THE JTWC FORECAST LIES CLOSE TO THE MULTI-MODEL CONSENSUS WITH HIGH CONFIDENCE. INTENSITY GUIDANCE IS ALSO IN STRONG AGREEMENT, WITH ALL GUIDANCE SHOWING RAPID WEAKENING AND DISSIPATION BY TAU 48. FORECAST CONFIDENCE: TRACK 0 - 72 HR: HIGH INTENSITY 0 - 72 HR: HIGH// NNNN