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Technical / Discussion Tropical Cyclones 2019-2020

  • 05-12-2019 4:58pm
    Registered Users Posts: 358 ✭✭

    First system for the south Indian ocean.
    Cyclone Ambali formed yesterday southwest of Diego Garcia, and is currently rapidly intensifying. So far, the storm has estimated winds of 100mph (160kph) with higher gusts, and the intensification phase isn't yet complete. The storm is likely to continue towards the southwest but rapidly weaken this weekend into early next week.

    Land impacts are unlikely, but up to 100mm of rain could fall on St Brandon, and a 5% chance of tropical storm conditions in Mauritius.

    There another system north or Madagascar likely to be name Belna probably this evening or tomorrow.



  • Registered Users Posts: 358 ✭✭YanSno

    Explosive intensification of Ambali overnight is now Very intense tropical cyclone Ambali with gusts reaching 330km/hr.
    Still moving south south west at a speed of 13km/hr. Further intensification may occur during the day and Ambali is still forecasted to weaken rapidly as from tomorrow.

  • Registered Users Posts: 14,226 ✭✭✭✭M.T. Cranium

    330 km/hr must be close to a global record.

    Can you post any links to official tracking of south Indian tropical cyclones? I assume maybe it's Meteo France in charge?

  • Registered Users Posts: 358 ✭✭YanSno

    Meteo France, Mauritius Meteorological Station with the help of the Base in Diego Garcia monitors all cyclones in the south Indian basin.

    Well Ambali has suffered, travelling into dry air has caused the system to rapidly weaken.

    Official report from

    Earlier this morning at 0400 Ambali reached it's peak as follows :
    Cyclone Tropical Very Intense AMBALI 930 hPa.
    Maximum average wind speed over 10 minutes: 222 km / h (120 kt)
    Maximum gusting at sea: 313 km / h
    Position on Friday, December 6, 2019 at 4:00 am (meeting time): 10.5 South / 62.2 East.
    Distance from the Reunion coast: 1355 km north-northeast.
    Displacement: South-South-West 13 km / h.
    No alert on the meeting.

    It has now be classed as a Tropical disturbance.

    Link to follow cyclone tracking:

  • Registered Users Posts: 358 ✭✭YanSno


    Cyclone Ambali put on quite a show for us Thursday with it’s extreme rapid intensification phase. The system was upgraded to a tropical storm at 18:00 UTC Wednesday with winds of 35 knots (40 mph), and likely attained Category 5 intensity with winds of 140 knots (160 mph) 24 hours later – A 120 mph increase in 24 hours, the 2nd quickest intensification phase ever recorded behind Hurricane Patricia in 2015, and the quickest intensification rate ever recorded in the Southern Hemisphere.
    Ambali’s 120 mph increase in 24 hours is extraordinarily rare. While rapidly intensifying storms do happen every year, a storm increasing 120 mph in 24 hours does not. Conditions were nearly perfect for rapid intensification of Ambali. 30C waters were in the storm’s path shortly after formation for at least 2 days, along with wind shear less than 5 knots near the storm’s peak intensity. The storm’s record peak intensity makes it the first Very Intense Tropical Cyclone on the local scale since Fantala in 2016, and the only A name in the basin to reach that status.

    As Ambali continues to weaken, Belna is intensifying – and is a significant threat to Madagascar.

  • Registered Users Posts: 358 ✭✭YanSno

    Cyclone Tropical BELNA 977 hPa.
    10-minute mean maximum wind: 130 km / h (70 kt)
    Maximum gusting at sea: 183 km / h
    Position Sunday, December 8, 2019 at 10:00 (Meeting time): 11.9 South / 46.5 East.
    Distance from the Reunion coast: 1370 km northwest.
    Displacement: South-South-West 11 km / h.
    Serious threat for Madagascar.

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  • Registered Users Posts: 8,219 ✭✭✭Gaoth Laidir

    This activity was due to a quick burst in the MJO in the western Indian Ocean, but all activ8ty should die down now as the MJO becomes indiscernible.

    From the BOM's weekly update, issued Dec 3rd.
    Weak Madden–Julian Oscillation to have minimal influence on Australian rainfall

    The Madden–Julian Oscillation (MJO) was indiscernible during the past week. While most climate models indicate the MJO will remain indiscernible for the next fortnight, some models indicate it might strengthen over the western Indian Ocean in the coming days, before rapidly weakening in about a week or two as it encounters the influence of the positive IOD over the eastern Indian Ocean. This region presents a hostile environment to a pulse of enhanced weather, such as the MJO, due to cooler than average sea surface temperatures, dry easterly winds and widespread, descending air which inhibits deep cloud formation.

    An MJO pulse over the western Indian Ocean at this time of the year typically decreases the chance of above-average rainfall across northern Australia and the Maritime Continent. However, if the MJO pulse remains weak or indiscernible, its influence on rainfall patterns over northern Australia is likely to be insignificant.

  • Registered Users Posts: 358 ✭✭YanSno

    Conditions are favorable

    The tropical disturbance is almost stationary in the Inter Tropical Convergence Zone (ZCIT).

    The environmental conditions are favorable for its intensification and a movement towards the South. Therefore, it will approach and influence the weather on the Mascarene Islands for the next few days.

    Weather deterioration is expected from Sunday in Mauritius.

    The evolution of this system is closely monitored by the Mauritius Meteorological Service.

  • Registered Users Posts: 358 ✭✭YanSno

    Tropical disturbance 96S located north northeast of Saint Brandon.

    Conditions are generally favorable and should allow this system to gradually intensify in the coming days. It could reach the stage of tropical depression in the next 12 to 24 hours. At 4 p.m. it was analyzed at the tropical disturbance stage by the Navy, bordering on the tropical depression stage. We can see on the that convection has intensified for a few hours even if the satellite presentation remains elongated and still poorly defined.

    ➡️ The models direct this system in the general direction of the area located just to the south-east of Mauritius.
    However, there has been a slight shift towards the east of the average trajectory of the models since this morning, which means that if these simulations were verified the system could pass a little further off Mauritius than envisaged yesterday.

    But nothing is less certain. The models are fluctuating which is normal because the exact positioning of the center which currently remains wide and still poorly defined is not yet precise. This can distort the simulations of trajectories upon arrival.

    Once the system is better organized, probably tomorrow, confidence in the forecast should increase considerably.

  • Registered Users Posts: 358 ✭✭YanSno

    Tropical Disturbance has continued to intensify and is now a Moderate Tropical Storm. It will be name Calvinia in the next few hours by Mauritius Meteorological Service. It's currently gusting at sea at 95kmph, it will countinue to intensify as conditions are favorable. Some wind sheer to the north west of the center but it's likely to drop on approach to Mauritius. Gfs has the centre stall doing a loop on Mauritius while continue to intensify. Most active bands are to the South East of the the system. A cyclone warning class 2 is currently in force in Mauritius. The possibility of cyclonic conditions on Mauritius and Réunion Island has now increased.

  • Registered Users Posts: 358 ✭✭YanSno

    A cyclone warning class 3 is in force in Mauritius.

    Over the last few hours, the severe tropical storm has remained almost stationary at about 120 km to the east of Mahebourg near the point 20.7 degrees south and 58.5 degrees east. It continues to intensify and a movement towards the west will bring the centre closer to mauritius.

    Cyclonic conditions, that is wind gusts of the order of 120 km/h, may occur over Mauritius by the early afternoon.
    Active cloud bands associated with CALVINIA will continue to influence the weather over Mauritius.
    Weather will be rainy. The rain will be moderate to heavy at times with thunderstorms. There will be localised accumulation of water and flooding.

    The new radar on Trou Aux Cerf has finally had its first storm within the 450km radius. Image below (copyright mms)

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  • Registered Users Posts: 358 ✭✭YanSno

    The observations during the last hours indicate that the severe tropical storm CALVINIA has started to undertake a loop to the East-South-East of Mauritius and continues to intensify. At 1300 hours,it was centered near the point 20.5 degrees South and 58.3 degrees East, at about 90 km off the coast of Mahebourg. While making this loop, the centre of CALVINIA may come dangerously close or over Mauritius. Wind sheer has considerably dropped,looks like Clavinia will looping around Mauritius for at least 12-24hr this is due to HP to the south . It may also reach Tropical Cyclone status while exiting the region. The center on the storm is starting to define and can be clearly seen below.

  • Registered Users Posts: 358 ✭✭YanSno

    Even Calvinia is a rather small system but should pack quite a punch. The outer bands are starting to wrap around the centre. Landfall is expected tonight around 10pm local time in Mauritius as per Meteo France. Some structural damage has already started on the island except the weather to deteriorate in the next few hours and simulation are going for over 200mm of rain.

  • Registered Users Posts: 358 ✭✭YanSno

    Well Calvinia has pretty much stayed stationary for the last 12 hours. It has been looping around but last radar shows it's been drifting towards the north west thus landfall on the south of Mauritius is highly likely . Winds over 150kmph are packed around the centre those gusts are around a 50km radius from the centre. It's a small diameter system any shift can make big impacts on the island. It will be a though night for the Mauritian population as the situation is very uncertain.

  • Registered Users Posts: 358 ✭✭YanSno

    After 24hr Calvinia has started to move south eastward.It's the first time that a storm stalled in that region for that long. Mauritius was spared as it didn't intensify any further than a strong tropical storm while being stationary and the active quadrant was along the south east side of Calvinia. Now that the Hp to the south is moving away Calvinia will accelerate while intensifying further it's now has a pressure of 980mb with gusts of 150kmph. Calvinia has no threat to land and is expected to become extra tropical in the next 2 days. I will post some of the damage caused on the island later.

  • Registered Users Posts: 358 ✭✭YanSno

    Some of the damages caused in Mauritius. From sources in Mauritius, Rodrigues, Diego thank you and i wish everyone here a happy new year.

  • Registered Users Posts: 358 ✭✭YanSno


  • Registered Users Posts: 358 ✭✭YanSno

    TROPICAL CYCLONE number 9 (GABEKILE) Maximum winds (averaged over 10 minutes) estimated at sea: 120 km / h. Maximum estimated gusts at sea: 165 km / h. Estimated center pressure: 983 hPa. Position on February 16 at 10 a.m. local time: 19.3 South / 75.0 E.
    No threat to land.

  • Registered Users Posts: 358 ✭✭YanSno

    A new tropical cyclone is forming off the coast of Madagascar today, and could rapidly intensify according to computer models to become a major system. The track forecast calls for the storm to pass near Mauritius and the island of Rodrigues, with tropical storm force or hurricane force winds possible on one or both of the islands.

    The storm is currently delivering significant rainfall to Madagascar, but is struggling to organise at the moment with no clear cut circulation, but this is expected to change quickly in the next 24-48 hours.


  • Registered Users Posts: 358 ✭✭YanSno

    Cyclone Herold was named by Meteo France earlier this morning, with rapid intensification possible in the next 24 hours and beyond. The storm is remaining close to the coast of Madagascar, and has actually moved further northwest than at this point twelve hours ago. The threat to the Mascarene islands remains virtually unchanged, however, Herold may have a little more time now to intensify.

    At the moment, the track of the storm is still likely to pass between Mauritius and Rodrigues, and if the forecast holds, rainfall will be limited to less than 100mm on all the islands.

  • Registered Users Posts: 358 ✭✭YanSno

    At 22:00, the strong tropical storm Herold was centered about 755 km northwest of Mauritius, in latitude 15.5 degrees south and longitude 52.5 degrees east. It travels in a general east-southeast direction at around 9 km / h. There are indications that Herold is intensifying and it is expected that the system will accelerate from tomorrow. On this trajectory, Herold could represent a potential threat to Mauritius from Monday evening

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  • Registered Users Posts: 8,219 ✭✭✭Gaoth Laidir

    Tropical Cyclone Nisarga made landfall just south of Mumbai in western India and close to Pune. Max sustained winds 75 knots. Very little talk about that, considering it's home to 20 million inhabitants and is India's financial centre.


  • Registered Users Posts: 8,219 ✭✭✭Gaoth Laidir

    The 2019-20 Southern Hemisphere tropical season ends today and has been very quiet relative to the longterm average.

    For the number of named storms and hurricanes it's been bang on average, but for major hurricanes it's been about half. Named storm days, hurricane days, major hurricane days and total ACE are also coming out around half the average, ranking in the lowest 10 years of the 40-year record since 1980.