The deluge was totally predictable, so why weren’t we warned?

I have listened to and read much of the media information and comment in regards to the recent tragic floods in the Toowoomba region. I have had a great deal of interest but have been left looking askance at many of the irresponsible assertions regarding the cause being cast about in the media.

I am sorry to be critical but so much serious and “informed” comment by many in the media is just plainly wrong. I understand the real problem is not what is written or said by journalists but what is erroneously or superficially passed off as expert comment by many “educated experts”.

I am a sailor and have taken an avid interest in meteorology over the last few years. While I am an amateur I understand my viewpoints result from much theoretical reading, detailed observation and personal experience.

I predicted to friends, on Monday morning, “Toowoomba would be subjected to a huge deluge within a day or two”.

Many might have been surprised by this at the time and no doubt it would surprise many now, especially since the “facts” have all now been supplied by “authoritative” figures.

I hotly dispute many of the common assertions.

The Bureau of Meteorology’s reported description of Toowoomba’s rain as a “Superstorm” or a line of storms was wrong and simplistic. It was something quite different.

Experts have correctly described the La Nina as the cause of the floods but that is too general and is a somewhat vague explanation as to why so much rain fell in Toowoomba and surrounds, while similar was not experienced in other parts of Southeast Queensland.

Some have claimed what happened in Toowoomba was a once in a century event. Toowoomba over the years has experienced similar, although not as intense nor as severe, flash flooding.  I.e. The general pattern of the Toowoomba flooding, as excellently described and shown in the media, but after less severe deluges, has had the same general flood pattern.

But most of all I totally reject the assertion the floods in Toowoomba were not predictable. This has been a mantra used by people, from the Queensland Premier Anna Bligh down. An examination of the circumstances and weather over the Southeast of Qld clearly shows all the events were eminently predictable. The Bureau of meteorology maps and synoptic charts of the period, all on the public record, do give supporting testament to my conclusions.

What specifically has occurred over Southeast Queensland since before Christmas is a series of perfectly normal weather occurrences. Nothing has been particularly unusual about any of them.

Initially we were subjected to a traditional monsoonal trough. It descended from North Queensland and hung about for a few weeks before Christmas and this was what had led to a saturated and drenched Southwest Queensland, Darling Downs and Southeast Queensland. Secondly Brisbane, since Christmas, had been subjected to a rain depression and it was moving slowly westward. This depression had been caused by the quite fierce, in excess of 33 knots, coastal “South East Trade Winds”. They had blown for over a week.

Do you remember the storms in Bass Strait during the Sydney to Hobart? That’s where they originated. These rain depressions are a quite normal event for Queensland coasts and hinterlands.

Third an upper level Australian East Coast Low had formed over Christmas off Bundaberg.  These commonly form in Harvey Bay or off the coast at Coffs Harbour and usually blow themselves out at sea or can track south west inland. They act very similarly to cyclones in many ways but without the extreme winds. Winds can blow up to 50 knots.

Cyclones typically deposit most of their rain not on the coast but about 100 kilometres inland. It takes a little while for the air to cool sufficiently for condensation to form (See later). This Low was a result of the cooler SE trades coming into contact with The Australian East Coast Current flowing down from the warmer Coral Sea. This current warms the air, causes it to rise, in turn causing further cool air to come in, rapidly, whipping up the sea spray and causing it to warm and rise.  They do pick up huge amounts of sea water.

On a personal note I was once caught in a yacht in Harvey Bay while one of these East Coast Lows formed. The winds gusted up to 50 knots. The lasting impression I had, besides the humidity, was that I could not see beyond the pulpit of the yacht from the cockpit because of the spray coming off the ocean. The amount of moisture in the air was astonishing.

This latest current Low had travelled up and down the coast for a week, until it went ashore at Fraser Island last Monday, tracked southwest from TinCan Bay, through Maryborough, Blackbutt Ranges, Sommerset and Wivenhoe Catchments, the Lockyer Valley, Toowoomba, Bremer catchment and Dalby through to the Granite belt. It deposited the greater part of its massive load, about 100klms inland, over the Lockyer Valley and Toowoomba.

Here I feel it appropriate to explain how rain is caused. Rain/precipitation is condensation. If you look at your car windscreen you will often see condensation (warm air cooling) but there are no rain drops in your car.  To form raindrops/precipitation, condensation must form on something. Usually it is dirt or dust particles in the air. In most rains at sea and in particular tropical cyclones it is salt particles in the air, from the evaporated and warmed water, that enables raindrops/precipitation to form.

So what happened at Toowoomba was a combination and an unusual convergence of three quite normal Queensland weather events. Principally an East Coast Low crossing the coast at Fraser Island and Tin Can Bay and tracking southwest through Toowoomba, second a SE Trades rain depression tracking westward from Brisbane to Toowoomba and third the previous severe soaking effects from a traditional North Queensland Monsoonal trough.

Questions do need to be asked.

Why wasn’t the deluge in Toowoomba predicted by the Bureau of Meteorology? Why were local “Severe Weather Warnings” not issued to the media and broadcast before the Toowoomba deluge, as had been regularly issued throughout the rains in other Queensland areas?

Why didn’t State Emergency Services undertake preparations for flooding?

It was obvious the East Coast Low had crossed the coast as downpours had flooded Tin Can Bay, Gympie and the North Coast Hinterlands on the Monday morning. It should be noted warnings were issued in Gympie enabling retailers to remove stock.

It also needs to be asked why many, from the Queensland Premier Anna Bligh down, in the media are now saying the downpour in Toowoomba wasn’t predictable?

We pay these people to protect us. They miserably failed many people in the Toowoomba and Lockyer Valley regions.  They are all covering up a great omission and shortcoming.

They do need to be correctly informed and to hold those in error to account. We all deserve as much.

Many accounts in the media, and particularly radio and television, focus on easily quantified river levels, major and minor flood levels and the input from expert hydrologists. It occurs to such an extent, to me, it appears to be a sports scorecard and at times seems to be an attempt to portray the current Queensland weathers as a single extreme event somehow related to and proving climate change. At the same time there is a paucity of information regarding rainfall. To me it seems, with the emphasis on the rivers, many of the media and the experts have forgotten that rivers don’t cause floods.

Floods are caused by rain… which is what happened in Toowoomba … in a cyclonic volume.

 

Keith Kennelly   14 January 2011

 

http://onlineopinion.com.au/view.asp?article=11475&page=0

 

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