Cyclone watch and other meteorological interests.

SaveH2O · Sep 09, 2017 2:26 pm

Last night, Super Hurricane IRMA underwent what is known as an eyewall replacement cycle. During these phases, the eye weakens and another eye comes in to replace the first. During this phase, IRMA decreased in strength from Category 5 to 4. I have linked a full explanation of this cycle below.

https://en.wikipedia.org/wiki/Eyewall_replacement_cycle

IRMA is expected to soon resume its monster category 5 status because it is currently over warm waters between Cuba and the Bahamas with a stretch of even warmer water between it and Florida. Florida is now certain to take a direct hit down its entire length.

The eyewall replacement cycle in many ways is like a recharge which is not good news when a major storm is about the hit a heavily populated area. The massive size of this storm and its very low pressure will create extremely dangerous storm surges for 15 to 18 hours or longer. At high tide, the Florida sea walls are barely one metre above high tide and a storm surge of three or four metres will be catastrophic.

There have been several news services that have been transmitting full time live coverage on You Tube for several days now.

The Earth Nullschool wind map https://earth.nullschool.net/ can detail an amazing amount of information by altering the settings. In the screen shot below, by clicking on earth and changing the settings to Ocean Waves HTSGW (significant wave height) and pointing the cursor to any position and clicking the mouse, a green circle will appear and you can then see the wave heights in that location. The location I have chosen is where IRMA is currently skirting the Cuban coast, you will see the coordinates on the screen at the left and the wave height which is currently 7.00 metres.
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SaveH2O · Sep 10, 2017 3:58 pm

Hurricane IRMA hugged the Cuban coast and the eye made partial land fall, damage and flooding is significant. Making landfall has weakened IRMA to category 3 but it will strengthen before making landfall on Florida. Tracking will now be west of Florida but this gives this monster storm more time over warm waters and with very low pressure, storm surge over huge areas will be catastrophic.

The extended northerly duration of this hurricane's force also brings crisis to northern areas not previously under mass evacuation. Nearly 7 million people have already evacuated from Florida but many more remain.

It is still several hours before IRMA has full impact on Florida but hurricane force winds, minor storm surge and widespread blackouts are already being experienced.

A good channel broadcasting with live crosses and video is linked below.

https://www.youtube.com/watch?v=mnShcQ5N_QQ

Spare a thought everyone.

SaveH2O · Sep 11, 2017 1:35 am

. Setting the Earth Nulschool map to Ocean, Current and SST (Sea Surface Temperature) shows the water temperature that IRMA is travelling over. Left clicking the mouse brings up the green circle wherever you place the cursor.

IRMA is directly under the green circle in the screen shot below and the top left hand box shows that the temperature is a very warm 30.5C. The larger box shows a temperature scale represented by different colours. The water that IRMA is travelling over is at the top of the temperature scale and this warmth will power up the storm's intensity until the eye moves over land and weakens.

Current reports have the pressure continuing to drop which means that IRMA is continuing to gather strength. It is currently category 4 but this relates to wind speed, the danger is with the low pressure which causes storm surges and flooding on the low Florida peninsula.

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SaveH2O · Oct 11, 2017 5:23 pm

Anyone in Adelaide wondering where the wild winds are coming from only need to look at the Earth Nullschool wind map showing the South Polar jet stream.

South Polar jet streams rotate clockwise.

A screen shot is shown below.

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SaveH2O · May 09, 2018 8:36 pm

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Victoria and Tasmania have been on a cold, wet and windy weather alert for the last few days which has now arrived. The cause of the weather can be seen in the image above that shows the South Polar Jet Stream looping north, bringing the weather off Antarctica and the Southern Ocean with it.

The image above which shows the jet stream wind patterns at about 35,000 feet can be seen in real time by going to https://earth.nullschool.net/#current/w ... -52.09,437 then clicking on "earth" and entering "250" (1/4 atmosphere) as the new height value. You can control numerous values including time and date images from the earth pop up box.

The jet stream acts as a fence to contain the polar weather but the jet stream is travelling much slower than usual and like a slow flowing river, it has meandered and stretched. The 'loop' that can be seen west of Tasmania in the image has bought the cold, windy weather with it. Fortunately, the current weather event will not be as severe in Victoria on this occasion as it would be if the jet stream loop reached just a few hundred km further north and was travelling faster but Tasmania will effectively be given a dose of Antarctic weather.

Jet streams are very high fast moving air currents with influence over the lower air layers. A few years ago, the jet stream looped higher into South Australia and the new record wind speeds twisted and destroyed electrical pylons, leading to SA losing all power.

News reports in Australia rarely mention the South Polar Jet Stream's pending influence on our weather, unlike Northern Hemisphere countries that are more severely influenced due to the Arctic's rapid temperature rise that has lessened the pressure gradient between the Arctic and the Equator which in turn has substantially weakened the North Polar Jet Stream. It is somewhat interesting however that the latest South Polar weather pattern has been referred to in some media outlets as an Antarctic Polar Vortex without any further explanation. Mushrooms anyone?

The Antarctic has noticably warmed over the past few years and will continue to do so. Southern Australia new home and infrastructure design needs to factor severe high wind events in anticipation of the inevitible.

EDIT: May 10, 1.15pm.
The 'loop' has now pushed further north into Victoria which will also influence the ACT and NSW weather. This is just a minor precursor of what to expect after the 2020 watershed.
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SaveH2O · Jul 17, 2018 3:39 pm

Wondering why today is so cold and windy?

Blame it on the present northerly reach of the South Polar Jet Stream! It circulates clockwise.
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SaveH2O · Feb 22, 2019 9:31 pm

Tropical Cyclone Oma is a slow moving, southerly tracking and increasingly large cyclone that has been in the news for more than a week after inflicting heavy damage on Vanuatu and New Caledonia then tracking towards South East Queensland. Right now (22.00 AEST), the eye is approximately 700 km east of Brisbane.

The cyclone can be tracked by using the link below. The link can measure a variety of things including mean sea level pressures, sea surface temperatures as well as going back in time, settings that I will use in this post.

https://earth.nullschool.net/#current/w ... -26.66,719

One thing that has to be understood is that cyclones get their 'fuel' from warm waters that need to be +26.5C at least 50 metres deep. Once they venture into cooler waters, they lose their strength but the remnant tropical low depression can still pack a punch and some serious rainfall. A tropical cyclone's tracking is also very unpredictable!

TC Oma has been tracking slowly and increasing in size through warm waters from north of New Caledonia but has now reached cooler waters and been downgraded to category 1. Most of the water between TC Oma and the Australian coast is less than 26C but with slowly increasing warmer sea temperatures, it is a certainty that Brisbane will eventually be hit directly by a cyclone and TC Oma serves as a warning of this stark reality. Apart from the inevitable coastal erosion and other damage that TC Oma will inflict on the NSW and Queensland coast, the main interest is in how far south it will track.

Clicking on the nullschool link will bring up the Australian east coast and clicking on EARTH at the bottom left will bring up a control panel. The image can be changed by clicking the cursor on the settings. In the image below, the settings have been set to ocean, currents and SST (sea surface temperature). Clicking anywhere on the image bring up a green circle that will show the selected values in the top box for the chosen area. In this instance, it shows the waters just off Brisbane as being 27.1C at 11 am on 21 February.

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TC Oma can be easily tracked by clicking the arrows next to Control and hovering the cursor over the arrows will show their values. The image below has a setting of Air, 1000 and MSLP (Mean Sea Level Pressure) and shows TC Oma's location at 20.00 hours today (22/02/2019). By going back in time, we can see TC Oma's most recent tracking. I have also clicked TC Oma's eye to bring up a green circle which has set TC Oma's location at 20.00 local time today.

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The next image shows TC Oma's location at 17.00 today and what is noticable is the small deviation to the south east to TC Oma's current location.Tonight's real time tracking should be very interesting.

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The next image has jumped back a further 6 hours to 11.00 am local time today.

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And the next image has jumped back another 24 hours to 11.00 on 21 February.

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EDITED: 25 February. Corrected a time and date reference.

SaveH2O · Feb 23, 2019 9:45 am

TC Oma is still tracking south into colder waters after suddenly tracking east for a few hours earlier this morning.
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2019-02-23 08.00 local. The green circle marks the eye.

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2019-02-23 05.00 local. Still tracking south. Green circle is the 08.00 local time location.

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2019-02-23 02.00 local time. The green circle (08.00 am location) is hard to see but it is east south east of the 02.00 eye's location. This signifies the easterly tracking that happened sometime between 02.00 and 05.00.

TC Oma's eye has also weakened over the last 6 hours. The hPa readings at 02.00, 05.00 and 08.00 were 984 hPa, 985 hPa and 987 hPa respectively.

There are predictions that TC Oma will soon track north into warmer waters. The next 18 hours will be of huge interest.

SaveH2O · Feb 28, 2019 9:59 am

With more windy hot conditions over the next several days, the risk of serious bush fires remains high for large areas of Australia.

The Australian Government Geoscience Sentinel Hotspots link below allows you to check the number and location of fires in Australia, New Zealand, Papua New Guinea, Indonesia, Borneo and the Philippines.

https://sentinel.ga.gov.au/#/

SaveH2O · Aug 07, 2019 12:20 pm

The south polar jet stream is slowly moving north, bringing Antarctic weather closer to our southern doorstep.
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SaveH2O · Aug 10, 2019 11:13 am

The current time wind map shows the South Polar jet stream stretching over the Australian southern coast, bringing cold air and strong winds with it.

The Americans refer to the jet stream as a polar vortex, something they and other northern regions now regularly experience due to Arctic warming causing the north polar jet stream to stretch and elongating southward. The Arctic has warmed much faster than Antarctica but warming in Antarctica is now happening at a rate not previously expected.

The decreasing pressure gradient between the poles and the equator is also a reason why cyclones are becoming more powerful and making landfall further south. The Australian building codes and builders need to adapt to Australia's changing weather patterns now!
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SaveH2O · Nov 15, 2021 12:42 pm

Tasmania.meets Antarctica.
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SaveH2O · May 30, 2022 11:28 am

Current weather news reports warn of a "polar blast" bringing cold weather to southern Australia but what causes a "polar blast"..

The screenshot below shows the South Polar Jet Stream has temporarily extended north far enough to reach over the southern Australian mainland. As Antarctica continues to warm, so too will the pressure gradient between Antarctica and the Equator continue to weaken which in turn will see the South Polar Jet Stream gradually extend more northward more frequently.

Antarctica is bottom/centre in the screenshot.
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Liliana · May 30, 2022 11:39 am

SaveH2O

Current weather news reports warn of a "polar blast" bringing cold weather to southern Australia but what causes a "polar blast"..

The screenshot below shows the South Polar Jet Stream has temporarily extended north far enough to reach over the southern Australian mainland. As Antarctica continues to warm, so too will the pressure gradient between Antarctica and the Equator continue to weaken which in turn will see the South Polar Jet Stream gradually extend more northward more frequently.

Antarctica is bottom/centre in the screenshot.
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So does that mean we will oscillate between really high temperatures and really low temperatures and nothing in between?

SaveH2O · May 30, 2022 11:51 am

Increasingly hot spells and cold snaps with strong winds as already predicted and realised but there will always be an "in between".

The North Polar Jet Streams are a basket case now whereas the South Polar Jet Streams are still strong but weakening. As they weaken, they stretch and reach further north. Even an additional 100 km northern reach will have far reaching consequences for Australia.

The northern hemisphere news outlets are more informative about changes in the Arctic than ours are about changes happening in Antarctica but the coming Arctic methane bomb will affect all.

SaveH2O · Jun 07, 2022 9:58 am

The South Polar Jet Stream acts as a fence to keep the Antarctic weather south. Successive northern loops are why much of Australia remains cold, wet and windy.
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SaveH2O · Aug 05, 2022 5:19 am

The cause of current strong winds.

South Polar jet stream August 4 13:00 pm AEST.
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SaveH2O · Sep 26, 2022 9:36 am

Our northerly neighbour the Philippines was hit last night by Super Typhoon NORU which currently sits off the east coast and heading WNW towards Vietnam.

Super typhoon Nora is one of the most unusual massive storms ever seen due to its unprecedented sudden strengthening as it travelled east over hot water towards the Philippines and its capital Manila which escaped a direct hit by only 50 km.

The huge concern now is the affect the large body of even hotter water directly between it and Vietnam will have on its strength, water as hot as 30.5C which is 2.4C above average.

The purple in the screenshot below indicates this very hot water and the green circle is a 'click on' facility that can show everything from wave heights to ocean and land temperatures and even pollution in any chosen area. Just click Earth in the bottom left corner to bring up the box where you can then choose whatever you want to study.

https://earth.nullschool.net/#current/o ... 758,15.989
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SaveH2O · Nov 02, 2022 7:59 am

South Polar jet stream shown looping over Adelaide and Victoria on 1 November 16:00 2022. This will become more regular in coming years as the South Polar - Equator pressure gradient continues to gradually weaken as Antarctica continues to warm.

As the pressure gradient weakens, the South Polar jet stream will 'stretch' as the North Polar jet stream has done. Stretching is what causes the 'loops'.
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SaveH2O · Sep 06, 2024 8:35 am

Why has Southern Australia been experiencing weeks of unusually strong winds?

These high winds are a result of a sudden and dramatic heating event in early July, where temperatures in the atmosphere 20 kilometers above the east Antarctic coastline increased by more than 50°C. This phenomenon, known as a Sudden Stratospheric Warming (SSW), has since propagated down towards the Antarctic surface.

The increased air pressure from the SSW has reduced the pressure gradient between the South Pole and the Equator, weakening the South Polar jet stream (polar vortex), causing it to stretch and extend northwards to the Southern Australian coastline.

While SSWs occur every other year in the northern hemisphere, they are rare in the southern hemisphere and have never previously been observed in winter.

Alarmingly, Antarctica has also experienced recent rapid warming and historically low sea ice levels post-summer. A continued weakening of the Polar Vortex can be expected in the coming years.

Despite the damage and disruption caused by the severity of these weather events, many Australians remain unaware of the underlying causes due to local television and news outlet's weather reports often failing to provide comprehensive explanations. In contrast, American media frequently discusses the impacts of the weakened North Polar jet stream during their winter months, offering a more informed perspective on similar phenomena.

For a detailed explanation of the current weather patterns affecting Southern Australia, I recommend reading the ABC News article: “Antarctica warming over 50°C” that I have linked below.

https://www.abc.net.au/news/2024-07-27/ ... /104142332