Friday 5 January 2018

Bushfire threat - the cost of leaving before the fire. Part 2

Referring to my posting last Wednesday, 3 January, as of 4.30 PM this afternoon BOM is holding to its prediction for Saturday:

Weather Situation

A high pressure system over the Tasman Sea will move slowly eastwards today as a cold front enters the Bight. The front will move rapidly eastwards on Saturday, reaching the far southwest of the State during the early afternoon, central districts during the evening then weaken over the far northeast during the early hours of Sunday. A high pressure ridge will extend across Victoria during Sunday, while a low pressure trough develops over New South Wales. The trough will extend over northeastern Victoria on Monday while a high pressure system develops over the Bight. The trough will move away to the east on Tuesday as the high moves across Tasmania.

Forecast

Very hot and sunny with fresh and gusty north to northwesterly winds. A squally southwesterly cool change developing in the west in the afternoon reaching the central districts during the evening. Isolated showers possible over the southwest following the change. Areas of raised dust possible over the northwest near and following the change. "Early morning fog in Gippsland. Very hot and sunny with fresh and gusty north to northwesterly winds. A squally southwesterly cool change developing over the southwest during the afternoon, reaching central districts during the evening. Isolated showers possible over the southwest at night. Areas of raised dust possible over central and western districts near and following the change.

Fire Danger - Extreme in the west grading to Very High in the east.

And a fire weather warning has been issued by BOM.

Total Fire Ban

Acknowledging the BOM prediction a total fire ban is in force for the whole of Victoria for Saturday, 6 January 2018.

Will history be revisited tomorrow ... 6 January is two days short of the forty-eighth anniversary of the January 1969 fires in Western Victoria, including Lara where 17 people lost their lives due to being caught in a bushfire on the Melbourne–Geelong Freeway?

Since 1969 Victoria has come a long way with the management of bushfire and advice to the public, but as individuals we still need to exercise exceptional situational awareness when it comes to how we will deal with an outbreak of bushfire in our area.

Whether to leave early or stay to defend our homes and other important assets

By now those who follow my postings will be aware that I'm strongly opposed to the one-size-fits-all "leave early policy" — see my 12 January 2015 post — as it leads to the loss of homes and businesses that could be saved if someone was in attendance to deal with ember attack.

Ember Attack

In my posting of 16 April 2016 I explain ember attack and the role of firebrands in spreading bushfire. Very recent examples of the devastating effect of ember attack were the large number of houses and other buildings lost due to wildfire (bushfire) entering residential development in California, USA. No doubt in my mind that much of the loss was due to embers starting fires and then those fires spreading from building to building with assistance of wind and garden vegetation. Here are a selection of video clips from You Tube showing the effect of fire entering what are relatively cleared urban areas well removed from undeveloped land that carried the fire:

1.   Aerial view of homes burned in Fountain Grove

Note the unburnt vegetation, a reliable indicator that it was embers landing around and on the buildings that led to them igniting then spreading from building to building.

2.   Aerial view of fire damage in Santa Rosa (Los Angeles Times)

Again, the absence of damage to the majority of trees indicates that most of the embers and sparks probably came in horizontally under the influence of wind.

3.   Before and after aerial view of fire damage, Los Angeles

Ember attack and building to building spread.

4.   Aerial view of Sonoma burning (CBS)

Deserted and burning from house to house.

Last one but worth viewing

5.   Aerial view of winery destroyed by fire (CBS)

Note the unburnt vegetation around these buildings. I suspect the roof burning is due to bituminous or timber shingle roof cladding, possibly attacked by embers.

Could it happen here?

The following two photographs from Google Earth are of northwest then southeast of Eltham and the third the southern side of Lorne Township in Victoria.

If fire gets into these or similar areas and Daylesford–Hepburn and Macedon-Mount Macedon also come to mind, there's unlikely to be sufficient firefighting vehicles or water bombing aircaft to save all the houses at risk. It happened on Ash Wednesday in the forest west of Woodend–Macedon with firebrands starting fires around Melton and further south. Following a violent southwesterly wind change firebrands and embers were coming off a long fire front and traveling towards the northeast. The rest is unfortunate history.

If you are thinking about staying to defend your home then you should heed the CFA's advice on preparing for fire and and particularly defending the property during a fire.m

If you do decide to stay, it must certainly be on the understanding that direct flame contact will not reach the building you will shelter in — unless of course it’s properly designed and constructed to BAL-FZ according to AS 3959 —2009 Construction of buildings in bushfire-prone areas.

Then the problem becomes that of that ensuring radiant heat from the fire will not be sufficient to destroy windows and ignite flammable timbers, and protecting oneself from high level convective heat or hot air and fighting those damnable embers, and this may take hours if your home is in the bush.

If you're unaware of what's involved with the passing of a bushfire the experience of four people who defended their home at Anglers Rest in 2003 is worth watching and it's probably rare footage. Note how the fire spreads ahead of itself by ember ignition and no actual linear fire front, and the tree canopies don't burn.

Remember Peter Lang's fight:

And if your plan is to stay, you will need supplies of food, water and other essentials, as if there is a need to leave after the fire has died down you may not be allowed back for several days depending on the location and extent of the fire.

Country Fire Authority Act 1958 Section 31 Police to assist Chief Officer etc.

Subsection(4)

Nothing in this section or section 30 shall authorize the removal from any land building or premises of any person having any pecuniary interest therein or in any goods or valuables whatsoever thereon.

Then there is the need to be able recharge mobile phones and maybe tablets. A generator may be useful for keeping the fridge and freezer going.

However any decision to stay and fight is yours, I'm merely trying to provide you with information to help you with the decision. If you have doubts on your level of preparedness and personal strength to take on what can be a very physical and emotionally challenging task, then go early and before you are likely to be caught in a fire.

Why am I making this posting? I'm doing it because the government and its agencies should be doing more to make us aware of how fire will arrive and how to deal with it, they should be encouraging the development of a firefighting partnership and allocating their — actually ours — resources to work in-conjunction with well prepared residents instead of encouraging everyone to leave the day before days such as that predicted tomorrow. Had this been done in the several days lead-up to the Wye River–Separation Creek fire no doubt the number of homes lost would have been reduced and the horrendous reestablishment red tape and excessive costs being experienced by people simply wanting to rebuild avoided.

I wonder how many homes across Victoria will be empty tonight?

What also worries me are those people who leave it to the last minute and are ultimately advised to "shelter-in-place" having previously been informed that they should "leave early". With no information on what to expect how will they respond when the fire comes over the back fence, run and die outside?

Note that the coloured text indicates URLs to be clicked on.

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Wednesday 3 January 2018

Bushfire threat — be wary of warnings that can amount to 'crying wolf'. Part 1

Victoria has entered the bushfire season and we can now expect warnings from the Bureau of Meteorology (BOM), Emergency Management Victoria (EMV) and the fire agencies.

Every year presents a challenge to BOM, EMV, etc., on how to warn us of bad or "spike" bushfire potential days without overdoing it.

To help avoid us being turned off by bushfire threat warnings we need to understand the relationship between weather and the quantity and dryness of bushfire fuel.

Currently, next Saturday, 6 January 2018, is shaping up as a day we should be wary of predicts the BOM:

"Very hot and sunny day with fresh north to northwesterly winds, gusty at times. Winds tending fresh and squally southwesterly from the west in the afternoon with a cool change, reaching the central districts during the evening."

Yesterday, bushfire scientist David Packham provided the following advice concerning the bushfire threat anticipated for next Saturday. I have highlighted in red the parts that convey the message. Remember, ember attack is the main cause of fire spread, clearly obvious from the extent that fire reached into the settled areas of California a short time ago.

“In a paper discussing bushfire conditions published in Geophysical Research Letters ( American Geophysical Union, 19 Feb 2015), Prof Michael Reeder (Monash Uni), Thomas Spengler (Uni of Bergen) and Ruth Musgrave ( Scripps Inst. Oceanography, Uni of California) showed a connection between extreme bushfire weather and the breaking of the Rosby waves as indicated by extreme cold fronts.

“There is an average of 1.4 extreme cold fronts per year. Extreme cold fronts are defined as a difference of more than 17 deg C between the max temperature before the cold front and the max temperature on the day after. The most extreme cold front between 1979 and 2010 was 24.3deg C and the most extreme on record (13 Dec 1924(which was 24.9 deg). So much for "earlier than ever" fright speak.

“Reeder, Spengler and Musgrave summarises as "most of the catastrophic fires in the State of Victoria have been associated with the passage of extreme cold fronts".

“Saturday next (6 Jan 2018) is one of those days with a forecast temperature difference of 41- 20 =21 degrees. It is a very extreme cold front indeed.

“My estimate for the Forest Fire Danger Index is 48 for Melbourne Airport which is just in the "Extreme" category (Black Saturday 2009 was about 135). We can expect 1.5 kph rates of spread, non-survival crown fire and spot fire up to 5km ahead of a forest fire in the 25-30 tonne per hectare forest fuels.

“Because our catastrophic fires are associated with an extreme front does NOT mean that every extreme cold front has a major fire attache, fuel and dryness are as important.

There is the highest levels of fuel now available for thousands of years now that prescribed burning has just about ceased. What will save us next Saturday is the early season moisture. The Keetch-Byram Index (KBDI) for Melbourne airport (a good surrogate for all Victoria) is only15mm out of a max. of 200mm and not of concern until greater than 100mm. My "average" for Victoria (except the Mallee) is 36mm and with average drying the concerning level of 100mm will not be reached until the middle of March as the bushfire season finishes. So far the KBDI is showing a "normal" seasonal increase.

“So for next Saturday I can see very hot winds, heaps of fuel and damaging fires but not catastrophic due to residual moisture in the bush.

“There will be fires and some damage but it is too early and moist in this season for a catastrophe.”

I’ve known David Packham for many years and respect his opinion on bushfire (wildfire) and consequently provide the above as a useful item of intelligence to assist our planning for next Saturday.

Again, remember that ember attack is the main cause of fire spread. Many homes have been lost because of the "leave early" policy and many lives lost because people left it too late to leave or did not know to shelter until the fire front had passed.

The photo is from an on-line story by KTLA 5 TV News and is of "several homes destroyed in the Thomas Fire are seen on Dec. 5, 2017" and is worth looking at. To me, the question must be, how many of the homes lost would still be there if the residents had stayed to deal with ember attack?

One person's fight

Having heard the owner, Peter Lang, interviewed on a recent podcast I went hunting.

Owner of Safari West, Peter Lang's inspirational story published on-line in SFGate, San Francisco, but unfortunately you'll need to pick your way through the advertisements.

To me, one of Peter's comments stands out:

“We were able to extinguish that,” he said. “I use the big ‘we.’ Me and that hose. We are the we.”

Finally, remember we are looking at Saturday and the weather can be fickle.

It will be interesting how the agencies handle advice to the public.

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