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Tropical Cyclone Ophelia


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Posted
  • Location: Liphook
  • Location: Liphook

    Well another system thats moving off Australia and is trying to develop has just recently been upgraded to tropical cyclone 21 with deep convection present in the northern quadrant. Like Nicholas before it currently there does appear to be a little more in the way of stable air in the eastern quadrant which is robably with the shear that has been present with the system. This should become much less of a problem within the next 24hrs and so I see no reason why, at least now, that it won't become afairly powerful tropical cyclone and also having a tight LLC as well.

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    Posted
  • Location: Taunton, Somerset
  • Weather Preferences: Snow, thunder, strong winds. HATE:stagnant weather patterns
  • Location: Taunton, Somerset

    Indeed, I've been watching this one over the past few days and it's been remarkably well organised over land so it was only a matter of when it emerged over water for it to develop because it almost looked like a tropical cyclone over land! It looks like this new cyclone may do another Nicholas in staying away from a direct landfall for now which of course will allow it to get stronger. A general southwestward track is forecast in response to a steering ridge to the south. Sea temps are quite high in the area and shear is now low (this was something that was impinging on the system earlier but eased as it moved over water) so the only way is up for this cyclone.

    Satellite image of 21S: (the mass off the NW coast of Aus, soon to be Ophelia)

    xxirgms5wbbm.jpg

    Taken from CIMSS

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    Posted
  • Location: Taunton, Somerset
  • Weather Preferences: Snow, thunder, strong winds. HATE:stagnant weather patterns
  • Location: Taunton, Somerset

    BOM have upgraded the cyclone, naming it Ophelia. Spinning up really nicely now, and BOM expect it to be a cat 3 on the Australian scale by 48 hrs, and the JTWC expect it to be a 65kt cat 1 (SS scale) by 48hrs too.

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    Posted
  • Location: Western Isles
  • Location: Western Isles
    Storm Alert issued at 1 Mar, 2008 6:00 GMT

    Tropical Storm 21S is forecast to strike land to the following likelihood(s) at the given lead time(s):

    Green Alert Country(s) or Province(s)

    Australia

    probability for TS is 35% within 12 hours

    Green Alert City(s) and Town(s)

    Lombadina (16.5 S, 122.9 E)

    probability for TS is 35% within 12 hours

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    Posted
  • Location: Taunton, Somerset
  • Weather Preferences: Snow, thunder, strong winds. HATE:stagnant weather patterns
  • Location: Taunton, Somerset

    Thanks for the alert Cookie.

    Ophelia has strengthened today, up to 45kts according to the JTWC. Continued strengthening is predicted due to good outflow, low to moderate shear and increasingly warm sea temps. Ophelia is moving away from land on a general westward track and is likely to continue to head westwards for the next couple days due to a steering ridge to the south. The ECMWF shows this clearly:

    http://www.ecmwf.int/products/forecasts/d/...;!chart.gif

    (Ophelia is the 'L' and the elongated steering ridge is the 'H'). As you can see, the ridge is pretty strong with no weaknesses at present which should allow Ophelia to continue heading westward. If this track continues, the coast of NW Australia shouldn't be at too much risk.

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    Posted
  • Location: Liphook
  • Location: Liphook

    Yeah Ophelia has a decent shape to it right now with a tight center, its is taking in a little more stablre air from Australia like Nicholas did though with the system heading away from land that should decrease. At the same time the shear that was present has also eased off and has allowed some fairly decent strengthening to occur, which was helped by the fact it already had a decent shape. I wouldn't be all that surprised to see this system reach 90kts as long as the system doesn't head too far south...the problem with the Indian ocean is data probably isn't quite as frequant as overland and so upper highs and lows aren't always very well forecasted hence why we always see forecasting track problems. The ECM on its own suggests a westward track but the offical forecasts seem to take the system WSW instead.

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    Posted
  • Location: Western Isles
  • Location: Western Isles

    new alert!

    Storm Alert issued at 1 Mar, 2008 18:00 GMT

    Tropical Storm OPHELIA is forecast to strike land to the following likelihood(s) at the given lead time(s):

    Yellow Alert Country(s) or Province(s)

    Australia

    probability for TS is 65% currently

    Green Alert City(s) and Town(s)

    Lombadina (16.5 S, 122.9 E)

    probability for TS is 50% currently

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    Posted
  • Location: Taunton, Somerset
  • Weather Preferences: Snow, thunder, strong winds. HATE:stagnant weather patterns
  • Location: Taunton, Somerset

    Ophelia has continued to strengthen and is now at 60kts, with what looks like an eye-like feature starting to appear in latest satellite imagery. JTWC expect Ophelia to reach 100kts by 48hrs due to good outflow, low shear and high ocean heat content. BOM are now expecting Ophelia to become a cat 4 on the Aus scale by the end of the forecast period. Things are really looking good for Ophelia, and unlike with Nicholas, this system is not going to track as close to land which should ensure continued strengthening as KW says.

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    Posted
  • Location: Western Isles
  • Location: Western Isles

    another alert, says its effecting Australia!

    Storm Alert issued at 2 Mar, 2008 0:00 GMT

    Tropical Storm OPHELIA is forecast to strike land to the following likelihood(s) at the given lead time(s):

    Green Alert Country(s) or Province(s)

    Australia

    probability for TS is 40% currently

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    Posted
  • Location: Taunton, Somerset
  • Weather Preferences: Snow, thunder, strong winds. HATE:stagnant weather patterns
  • Location: Taunton, Somerset

    Ophelia has intensified slightly to 65kts, making it a cat 1 on the SS scale. Further intensification is forecast as shear remains light and sea temps warm on Ophelia's west to southwest track. However, shear could increase as soon as 24hrs away which will slow or halt intensification, and beyond 48hrs sea temps begin to fall away as Ophelia veers more southwestward around the periphery of the steering ridge. The JTWC also notes some drier air near the system, and they have backed off thier 100kt forecast of earlier, by now suggesting a more conservative peak of 85kts before conditions become conducive for slow weakening.

    It's worth noting that the southern convectional bands may well give some showers to coastal districts from Wallal to Karratha looking at satellite imagery. Ophelia's centre is still some distance away from land so any effects should be minimal.

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    Posted
  • Location: Taunton, Somerset
  • Weather Preferences: Snow, thunder, strong winds. HATE:stagnant weather patterns
  • Location: Taunton, Somerset

    Thanks Cookie.

    Ophelia has weakened slightly to 60kts, probably due to dry air infiltrating into the circulation. It's still possible for Ophelia to strengthen a little in the next 24hrs due to low shear and good sea temps but after that ocean heat content will taper off and shear is expected to increase which will weaken Ophelia again. The JTWC and BOM have backed off on the intensity forecast with JTWC only expecting another peak of 65kts and no stronger due to the less than ideal conditions now and the hostile conditions later.

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    Posted
  • Location: Taunton, Somerset
  • Weather Preferences: Snow, thunder, strong winds. HATE:stagnant weather patterns
  • Location: Taunton, Somerset

    Ophelia is stuck at 60kts, and appears it will not regain cat 1 status on the SS scale. The BOM and JTWC largely agree that Ophelia will keep tracking west-southwestwards then turn more southwards as she rounds the periphery of the steering ridge to the south. Sea temps are decreasing and Ophelia is ingesting dry air at the moment and the only thing allowing the cyclone to maintain intensity for now is good outflow. However, shear is expected to increase soon and coupled with even colder waters on the future southerly track means Ophelia will dissipate by 72hrs.

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    Posted
  • Location: Taunton, Somerset
  • Weather Preferences: Snow, thunder, strong winds. HATE:stagnant weather patterns
  • Location: Taunton, Somerset

    Ophelia has weakened to 50kts, and is now forecast to dissipate by 48hrs, possibly sooner. Dry air is really killing the system off, but low sea temps and high shear will bring Ophelia's eventual demise.

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    Posted
  • Location: Taunton, Somerset
  • Weather Preferences: Snow, thunder, strong winds. HATE:stagnant weather patterns
  • Location: Taunton, Somerset

    Ophelia is now pushing southwards on the western periphery of the subtropical steering ridge over Aus. Convection is waning and Ophelia is currently at 40kts. Dissipation is expected to occur later today or early tommorrow as shear and cold waters persist on the southward track.

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