nw australia Tropical Cyclone Alessia

[Somerset Squall]

The second tropical cyclone of the 2013-14 Southern Hemisphere tropical cyclone season has formed, this time in the waters of Northwest Australia (the first was in the South Indian Ocean also, last month, east of Madagascar). The cyclone has winds of 35kts according to JTWC. The low was noted a few days ago just south of Indonesia, and has since dropped south whilst slowly developing. Overnight, the system has become much better organised, with deep convection over the increasingly well defined LLC, and formative banding features taking shape. I expect BOM to name the system soon. The environment ahead seems to favour at least some modest intensification over the next few days. The waters off the NW Australian coast are certainly warm enough, and looking at CIMSS wind shear charts, shear looks fairly low, at least for now, but are higher further north:

Track wise, it seems fairly straightforward. An equatrorial ridge seems to be now steering 02S to the east, and this is expected to continue over the next few days, taking 02S north of Kuri Bay, into Kalumburu, into the Josef Bonaparte Gulf before final landfall south of Darwin. Some minor adjustments in track can be expected, but models are in quite good agreement on this scenario.

Edited November 22, 2013 by Somerset Squall

[Coast]

 

The low is not expected to cause gales over the northern Kimberley during Friday. Gales may develop along the northern Kimberley coast on Saturday as the system approaches. Overnight Saturday into Sunday it is likely to brush the northern Kimberley coast. During Sunday it is likely to weaken as it approaches the west coast of the Top End. 

 

Rainfall from this system is likely to be confined to coastal areas. Even in coastal areas, rainfall totals are expected to be less than is typical with a tropical low or cyclone.

 

DFES-State Emergency Service advises that there are no community alerts at present. 

Communities between Cockatoo Island and WA/NT Border should listen for the next advice.

 

 

http://www.bom.gov.au/products/IDW60281.shtml

[Styx]

 

ABC meteorologist tonight says it will only be the fourth cyclone Australia has seen in November in 'modern times'. Wish he was more specific about that! 

[Vorticity0123]

ABC meteorologist tonight says it will only be the fourth cyclone Australia has seen in November in 'modern times'. Wish he was more specific about that! 

 

The Bureau of Meteorology from Australia has a list of tropical cyclones and their occurence per month, between 1988-2003. It shows that there were no tropical cyclones at all which developed in the month of November. This means that TC activity in November is indeed quite unusual in the Australian basin. The frequencies of TC's per month are listed below:

 

 

The last tropical cyclone existing in November is cyclone Anggrek (formed in October) in the 2010/2011 TC season.

http://en.wikipedia.org/wiki/2010%E2%80%9311_Australian_region_cyclone_season

 

Currently, Alessia looks quite disorganized, with only a burst of convection occuring over the center and no convective banding.

 

 

The JTWC has upped the intensity to 45 knots. BOM still classifies the system as a cat.1 tropical cyclone (winds between 38 and 54 knots). Given its current satellite presentation, I don't expect Alessia to intensify beyond its current intensity.

 

What i find quite strange is that some intensity models bring the system up to 80 knots, and one even to 150 knots. That doesn't seem quite realistic to me, but still nice to note.

 

 

 

Sources:

http://www.ral.ucar.edu/hurricanes/realtime/plots/southernhemisphere/2014/sh022014/intensity_late/ash02_2013112212_intensity_late.png

http://www.bom.gov.au/cyclone/climatology/wa.shtml

http://www.nhc.noaa.gov/satellite.php

http://en.wikipedia.org/wiki/Tropical_cyclone_scales

Edited November 22, 2013 by Vorticity0123

[Somerset Squall]

Alessia is closing in on it's first landfall. The convective canopy has shrunk due to dry air infiltrating Alessia, but the system retains winds of 45kts. As Alessia drags across land, it will weaken before briefly emerging into the Josef Bonaparte Gulf, before a second landfall, south of Darwin. Alessia is then expected to degenerate into a remnant low. The remains could enter the far south of the Gulf Of Carpentaria, but the system is not expected to spend enough time back over water to regenerate.

[Coast]

Tropical Storm ALESSIA: Probability of tropical storm winds to 72 hours lead

[Coast]

 

Tropical Cyclone Alessia has moved away from the north Kimberley coast and is currently approaching the western Top End. The centre of this small tropical cyclone is expected to cross the coast overnight between Darwin and Port Keats. 

 

GALES with gusts to 95 kilometres per hour are expected to develop this evening on the coast between Port Keats and Darwin, including the Tiwi Islands. Gales may develop south of Port Keats if the cyclone takes a more southerly track. Gales have eased on the north Kimberley coast.

 

Heavy rain is likely to cause localised flooding over the western Top End as the cyclone makes landfall and moves inland.

 

Tides will be HIGHER THAN NORMAL between Port Keats and Point Stuart, including Darwin and the Tiwi Islands. Large waves may produce MINOR FLOODING of low-lying coastal areas.

 

The Territory Controller advises residents from Port Keats to Dundee Beach to seek shelter in accomodation constructed to the building code.

 

Residents of Darwin and Rural Areas and the Tiwi Islands are advised that now is the time to make final preparations to your home shelter area

 

 

http://www.bom.gov.au/products/IDD65011.shtml

[Coast]

Tropical Cyclone Alessia a no-blow for Top End

 

Former tropical Cyclone Alessia is being branded a flop by Top End residents as the weather bureau cancels all severe weather warnings for the Top End. A remote nurse, in the town to first experience the effects of Cyclone Alessia as it crossed the Northern Territory coast last night, said the storm was an anti-climax. Susan Wilson from Wadeye, southeast of Darwin, said she hadn't heard any reports of damage done overnight, and was happy the storm left the community unscathed. "Watching the Weather Channel and on the BOM site and what have you, and they're telling us we have heavy rain, but nothing, nothing has happened," Ms Wilson said.

 

The bureau downgraded Cyclone Alessia to a tropical low last night. Bureau senior forecaster Sally Cutter said the upper Adelaide River, just north of where the weather system hit land, experienced high winds and got about 54 millimetres of rain. She said the low was heading east and would move over the western Roper-McArthur region in the next day or so. While the other warnings have been cancelled, Ms Cutter said a flood threat advice was is still in place.

 

"That's for the Darwin, Arnhem and Roper-McArthur districts," Ms Cutter said. "That'll initially be in the, basically, the Top End area - and then extending down into the Gulf Country sort of early next week as the system just goes and sits down in that area, and brings in the potential of heavy falls, widespread falls of 20 to 50 millimetres, with scattered falls of 50 to a hundred."

 

Northern Territory Police say Darwin has emerged largely unscathed. Schools are open and government workers are expected at work, though many Darwinites were holding cyclone parties last night in anticipation of a sleep-in. Duty Superintendent Helen Braam said no one was injured during last night's storm and there were no serious traffic accidents. "We had quite squally sort of weather, a lot of wind and a bit of rain," Supt Braam said. "That brought down a couple of trees around the Northern Suburbs and out at Howard Springs. "A bit of localised flooding around Palmerston but otherwise that was about it."

 

The Territory Insurance Office is urging people to make sure they've got adequate insurance cover with the arrival of this year's wet season. General manager Michael Hoare said there was a 72-hour waiting period for a policy to take effect if it was taken out during a cyclone-watch period. "It's just a reminder to make sure they've got that in place, because we are heading into the wet season and it does give you a feeling of, I suppose, security, making sure that your assets are covered in case something does arise from a cyclone," Mr Hoare said.

 

http://www.abc.net.au/news/2013-11-25/tropical-cyclone-alessia-a-no-blow-for-top-end/5114590

[Styx]

Peak wind gust of 69kmhr/43mph in Darwin from this system.. 

[Coast]

Is Alessia on it's way back?

 

Former Cyclone Alessia could get a second go at roughing up the Top End, with a chance it may redevelop in the Timor Sea.

 

The weather bureau's tipping the low, which is now lurching about above the central Top End, will hit the Gulf of Carpentaria tomorrow, and may intensify briefly before wandering back west over the Top End on Thursday. The bureau predicts it'll reach the Timor Sea early next week, where it may redevelop into a tropical cyclone. The chance of it developing back into a cyclonic storm in the next three days is rated by the bureau as low - or between 5 and 20 per cent. The Bureau of Meteorology downgraded Cyclone Alessia to a tropical low last night.

 

The category one cyclone hit the Northern Territory coast at 9pm last night, packing winds of up to 95 kilometres an hour around Daly River, and 70 kilometres an hour near Darwin. More than 50 millimetres of rain fell at Adelaide River, the heaviest associated with the cyclone.

 

 

http://au.news.yahoo.com/a/20013316/former-cyclone-alessia-set-to-make-comeback/

[Styx]

Since it would have been out of action for quite a while, and not particually definable, and backtracking to 're form' over new waters, I wonder whether the BOM will classify it as a 'new' cyclone, giving it another name?

[Somerset Squall]

This is an interesting possibility. The remnant low of Alessia has now entered the far west of the Gulf Of Carpentaria, where convection has increased a little over the low. But as the steering pattern continues to reverse, Ex-Alessia will soon be back inland. But it could regenerate down the line when it emerges back over water, funnily enough, near where it formed.

If the low remains intact throughout, JTWC would keep the same name/number, as they did with TC30W the other week in the West Pacific and North Indian Ocean, which went a full 9 days before regeneration. I'm not sure what BOM's policy is, though they still are referring to the low as Alessia currently.

Edited November 26, 2013 by Somerset Squall

[Vorticity0123]

It is most likely that this low will indeed be renamed Alessia, once it regenerates. It would be quite extrordinary to have a cyclone have a double possibility of regeneration after interaction with land. 

 

The GFS has thrown in another solution regarding Alessia, as it develops it into a cyclone in the Gulf of Carpentaria. The cyclone then stalls for about 4 days, before moving back inland into the Top End.

 

At T+66h, Alessia can be seen meandering near the east coast of Top End.

 

While at T+120h, this system can still be seen sitting in the same place.

 

And finally, at T+156h, Alessia can be seen moving inland (backward) again.

 

Though this is only a model forecast with quite a big margin of error (only 100 km more to the west/east could make a very big difference regarding the intensity and possible cyclone), the GFS 06Z run showed the same solution.

 

EDIT: As a big suprise, tenacious Alessia seems to have become a tropical cyclone again to the east of Top End, looking at the last visible loop. The imagery shows a pronounced blob of convection with some banding features to the north. Though BOM hasn't assessed this as a cyclone yet, and JTWC has chances of development still at the "low" category, I'm quite certain that this is a tropical cyclone.

 

 

I think it won't be long before this system is once again recognized as a tropical cyclone. Quite an amazing cyclone!

 

And finally, a quick look at the conditions. Shear values are currently very low around Alessia, and are forecasted to stay that way for the next day or so.

 

Current SSTS are sufficiently warm to support a TC, with values up to 29 degrees Celsius.

 

 

Overall, the future track of Alessia (which seems still very uncertain to me) will largely control its intensity. It will be some very interesting TC watching!

 

EDIT 2: Although the cyclone does seem to be a TC on satellite imagery, TC intensity estimates argue against that, with only a T1.5 (25 kt) given. This would mean Alessia is at best a weak tropical depression.

 

(as from http://www.ssd.noaa.gov/PS/TROP/tdpositions.html)

 

Sources:

http://www.ssd.noaa.gov/PS/TROP/floaters/02S/02S_floater.html

http://www.wetterzentrale.de/topkarten/fsfaxsem.html

http://www.bom.gov.au/cgi-bin/wrap_fwo.pl?IDY00001.gif

Edited November 26, 2013 by Vorticity0123

[Somerset Squall]

Looking good though, I wouldn't rule out Alessia becoming a tropical cyclone again during it's visit to the Gulf Of Carpentaria. So many uncertainties regarding track- will be an interesting watch. Alessia, in one form or another, could be around for a while yet!

[Somerset Squall]

BOM have re-upgraded Alessia to a tropical cyclone over the southern Gulf Of Carpentaria. Looks well organised this morning:

 

 

 

[Coast]

 

I'll be back!

 

Just before Alessia was upgraded, this was the Herald Sun report:

 

The weather bureau has issued a tropical cyclone warning for coastal areas from Port Roper in the Northern Territory to Mornington Island in Queensland. Bureau regional director Andrew Tupper said there was a chance Alessia could build to a Category 1. "Lows in this area are notorious for doing what they want to do," he said. "There is a possibility it (Alessia) could stay out on water and develop further, it was developing slowly during the night; it has gales around the southern side at the moment and it's not far off a tropical cyclone structure."

 

The potential tropical cyclone is threatening the Port Roper and Mornington Island region. But Darwin isn't considered in danger at this point. Mr Tupper said the cyclone would have to track a "long way north as well as west" to be a problem for the NT capital. After 12.30pm today the following warning was issued: Ex-Tropical Cyclone Alessia is expected to redevelop into a tropical cyclone later today if it remains over Gulf of Carpentaria waters. The tropical cyclone is expected to remain close to the coast during the next two days.

 

GALES with gusts to 110 kilometres per hour are currently being experienced at Centre Island south of the centre of the developing tropical low. Gales are expected to further develop on the NT coast between Port Roper and the NT/Queensland border later today, and may extend further east to Mornington Island in Queensland tonight or early Thursday.

 

ABNORMALLY HIGH TIDES could cause MINOR FLOODING on the southern Gulf of Carpentaria coast between Port McArthur and Mornington Island tonight and tomorrow. HEAVY RAIN is likely to cause localised flooding in the Roper-McArthur District and coastal areas in Queensland Gulf Country west of Mornington Island during today and Thursday.

 

 

http://www.heraldsun.com.au/news/ex-cyclone-alessia-could-reform-and-build-to-category-1/story-fnk1w5y0-1226769683092

 

[Somerset Squall]

Alessia has made a third landfall, this time on the southern coast of the Gulf Of Carpentaria. Shear has increased over the system, seperating the convection from the LLCC, which is just inland. BOM have downgraded Alessia back to a low, and JTWC will probably follow suit (they re-upgraded Alessia this morning).Just what will happen to the remnant low is open to question, and is far from certain.

Edited November 27, 2013 by Somerset Squall

[Coast]

Seems to be chucking large amounts of rain on the Top End:

The former tropical storm Alessia reclaimed her title on November 27 in the Gulf of Carpentaria, as NASA's TRMM satellite passed overhead and observed heavy rainfall occurring in bands of thunderstorms around the storm's center.

 

NASA's Tropical Rainfall Measuring Mission or TRMM satellite passed directly above newly transformed Tropical Storm Melissa's center of circulation on November 27, 2013 at 02:25 UTC/10:25 p.m. EST on Nov. 26. TRMM's Precipitation Radar (PR) instrument found that rain was falling at a maximum rate of 50 mm/2.0 inches per hour west of the center, and in a large band of thunderstorms stretching from the east to the south.

 

On November 27 at 0900 UTC/4 a.m. EST Alessia's maximum sustained winds were near 35 knots/40 mph/62 kph. Alessia's center was located near 15.9 south latitude and 137.7 east longitude, about 105 nautical miles/120 miles/194.5 km west-northwest of Mornington Island, Australia. Alessia was moving to the east southeastward at 3 knots/3.4 mph/5.5 kph.

 

Mornington Island is located in the southern part of the Gulf of Carpentaria, and is part of the state of Queensland. The Gulf of Carpentaria is a shallow sea that is surrounded by land on three sides and the Arafura Sea to the north. The Northern Territory borders the Gulf on its west and south sides, while Queensland borders the Gulf to the east and southeast.

 

On November 27, the Australian Bureau of Meteorology or ABM, posted a Cyclone Warning for coastal areas from Port Roper to Mornington Island, and a Cyclone Watch was in effect for coastal areas from Mornington Island to Burketown. The Cyclone Watch from Burketown to Karumba was cancelled. Heavy rainfall and abnormally high tides may cause flooding in low lying areas Roper-McArthur District and coastal areas in Queensland Gulf Country west of Mornington Island, according to the ABM forecast. For updated warnings, visit: http://www.bom.gov.au/qld/warnings/.

 

Alessia is now forecast to make another landfall, and this time the final one, just west of Mornington Island on the mainland in Australia's Northern Territory. The Joint Typhoon Warning Center expects Alessia's landfall to occur on November 28 around 0600 UTC/1 a.m. EST. Thereafter, Alessia is expected to track to the south-southeast, further inland where it will dissipate.

 

 

 

 

http://www.sciencecodex.com/nasa_sees_alessia_reclaim_her_crown_as_a_tropical_storm-123836

[Coast]

Fizzling out finally:

 

Tropical Cyclone Alessia moved across Australia Top End over the weekend bringing heavy rainfall and gusty winds. Alessia weakened to a tropical low before moving back over the Gulf of Carpentaria earlier this week. While spinning over the warm waters of the gulf, Alessia reorganized into a tropical cyclone on Wednesday. By Thursday, the storm drifted southward and dissipated over the Roper-McArthur district of Northern Territory

 

 

 

http://www.accuweather.com/en/weather-news/tropical-cyclone-alessia-drenc/20386141

[Somerset Squall]

Mmm, maybe not Coast, because the remnant low of Alessia has moved back over water yet again. The low, instead of moving back west towards it's birthplace, has meandered northeast and has moved back over the warm waters of the southern Gulf Of Carpentaria, where convection is increasing once more. JTWC give ex-Alessia a MEDIUM chance of becoming a TC for the third time (within 24hrs).

Edited November 29, 2013 by Somerset Squall

[Coast]

Mmm, maybe not Coast, because the remnant low of Alessia has moved back over water yet again. The low, instead of moving back west towards it's birthplace, has meandered northeast and has moved back over the warm waters of the southern Gulf Of Carpentaria, where convection is increasing once more. JTWC give ex-Alessia a MEDIUM chance of becoming a TC for the third time (within 24hrs).

 

This one really won't go home! 

[Vorticity0123]

This one really won't go home! 

 

Alessia has found her new home, the Gulf of Carpentaria! She just really enjoys staying there.

 

SSTS are abundantly warm for her to remain alive, the only threat being upwelling of cool deep ocean waters (though I doubt this will be the case as the ocean is not very deep in the Gulf).

 

 

Currently, Alessia looks rather dishelved, with no deep convection associated with the system. Most of the convection dissipated around 11 UTC. However, knowing her, don't be suprised if one sees another burst of deep convection occuring.

 

 

For a short review on the cyclone, the track of Alessia is posted below:

 

Quite an extrordinary track Alessia has taken so far, with 3 landfalls and a tight loop in the Gulf of Carpentaria. However, as stated above, the cyclone is far from done yet, as it may regenerate in its very own Gulf, or near its birthplace, in the longer term, as the cyclone is forecast to move westward over the northern Kimberly coast. 

 

The forecast track, according to the AVNO model (I don't know how reliable it is) is as follows:

 

If it makes the trip over northern Australia, the it would have regenerated for the third time (or fourth, depending on if it regenerates in the Gulf of Carpentaria for a second time). If this occurs, then Alessia could be one for the record books. However, the uncertanity is still very high, so no quick conclusions can be made right now.

 

EDIT: Say hello to a healthy looking Alessia once again! First visible imagery show that the center is now fully tucked under a large burst of intense convection. This could help Alessia to spin up and become a depression once again! However, banding features are not apparent yet, and therefore, development is likely to be slow.

 

Sources:

http://polar.ncep.noaa.gov/sst/rtg_high_res/

http://www.nhc.noaa.gov/

http://en.wikipedia.org/wiki/2013%E2%80%9314_Australian_region_cyclone_season#Tropical_Cyclone_Alessia

http://www.ral.ucar.edu/guidance/realtime/plots/southernhemisphere/2014/sh022014/

Edited November 29, 2013 by Vorticity0123

[Coast]

Alessia has found her new home, the Gulf of Carpentaria! She just really enjoys staying there.

 

Settling in nicely once again....

 

http://www.bom.gov.au/products/IDR363.loop.shtml#skip

 

IDD10610

Australian Government Bureau of Meteorology

Northern Territory

Darwin Regional Forecasting Centre

 

Tropical Cyclone Outlook for Northern Region, including the Gulf of Carpentaria

 

Issued by the BUREAU OF METEOROLOGY, DARWIN

at 2:15 pm CST Friday 29 November 2013

 

Existing Cyclones in the Northern Region and Gulf of Carpentaria:

 

Nil.

Potential Cyclones:

 

Ex-Tropical Cyclone Alessia is located near the southern Gulf of Carpentaria

coast close to the NT/Queensland border and is causing active storms with heavy

rain. It is expected be near stationary over the next 24 hours before moving

west across the Top End, reaching the Kimberley north coast by early next week. 

     

 

Likelihood of a new tropical cyclone developing in the Northern Region on:

 

Saturday: Moderate,

Sunday:   Very Low,

Monday:   Low.

NOTE: The likelihood is an estimate of the chance of each system

being a tropical cyclone in the Region for each day...

Very low: less than 5%,   Low: 5% to 20%,

Moderate: 20% to 50%,     High: Over 50%.

 

The area of coverage for this outlook is the Ocean area south of 9S, between

125E and 142E, including the Gulf of Carpentaria, but excluding the area around

Timor [northwest of 11S 125E, 11S 128E, 09S 128E].

 

 

http://www.bom.gov.au/nt/forecasts/tcoutlook.shtml