This is posted on behalf of Terry Oakley, it is a message from a friend in the CFA (I believe):
Hi Terry
David’s just had a good look at the fire weather estimates and other forecast products for Tuesday.
His conclusions are that the forecast conditions are easing a very little. The forecast Forest Fire Danger Index is however still extremely high. Tullamarine is 138 which is a little less than the 150 for Feb 7.
The winds predicted on the mesolaps model is somewhat less than we see in the fire weather forecast especially for us here in the Latrobe Valley. Mesolaps gives us in the Latrobe Valley the change around late afternoon whereas the Fire weather estimates (latest issue 16:45 Sunday) are some hours later. I suspect that when the latest Estimates come out they will reflect these very slight easings. No confusion this is still a record black book day.
There is another good sign and that is that the forecasters and models are certain of small quantities of rain with the wind change. That will help a lot.
In summary we have a very severe fire situation especially for people with fire to the north of them. If folk are leaving then tonight is the time to do it. We for one would never leave but we have been preparing for weeks now.
The roadside are the worst I have ever seen in terms of fuel and are really death traps. Whereas they used to be linear firebreaks they are now linear fire wicks.
There is one interesting thing and that is the wind speeds are so high in grass lands that it is possible that the very high wind speed effect reported by McArthur in the 1960s of rate of spread starting to slow over 60 kph could be observed.
The conditions are such we could expect in forest areas rates of spread of 6 – 10 kph (about as fast as it gets), Flame heights of 30-70 metres and spotting up to 30km ahead. In grass lands the max rate of spread of 26 kph will probably occur and fire can be carried over eaten out areas as only a very little dead grass or even burning dried cow pads can be effective for spreading fires under these conditions.
The winds on the charts are showing as North rather than the more usual Northwest in these cases. The wind change is showing up as a west rather than the usual south west. This of course has implications for those around current fire areas.
The high winds will mean that some things that don’t start fires normally become of a much higher risk on Tuesday. Power lines clashing and arcing to trees for example, sparks from vehicles . So we are all prone to fast moving short notice fires. I would expect 100 or so of these throughout the state tomorrow. Most of these are likely to be put out by very fast CFA response but a few of them will get through.
I expect the new Fire Weather Estimates to be out soon and if there is any big changes I will email you again.
Regards
David PACKHAM
Another warning about Tuesday
This is posted on behalf of Terry Oakley, it is a message from a friend in the CFA (I believe):
Hi Terry
David’s just had a good look at the fire weather estimates and other forecast products for Tuesday.
His conclusions are that the forecast conditions are easing a very little. The forecast Forest Fire Danger Index is however still extremely high. Tullamarine is 138 which is a little less than the 150 for Feb 7.
The winds predicted on the mesolaps model is somewhat less than we see in the fire weather forecast especially for us here in the Latrobe Valley. Mesolaps gives us in the Latrobe Valley the change around late afternoon whereas the Fire weather estimates (latest issue 16:45 Sunday) are some hours later. I suspect that when the latest Estimates come out they will reflect these very slight easings. No confusion this is still a record black book day.
There is another good sign and that is that the forecasters and models are certain of small quantities of rain with the wind change. That will help a lot.
In summary we have a very severe fire situation especially for people with fire to the north of them. If folk are leaving then tonight is the time to do it. We for one would never leave but we have been preparing for weeks now.
The roadside are the worst I have ever seen in terms of fuel and are really death traps. Whereas they used to be linear firebreaks they are now linear fire wicks.
There is one interesting thing and that is the wind speeds are so high in grass lands that it is possible that the very high wind speed effect reported by McArthur in the 1960s of rate of spread starting to slow over 60 kph could be observed.
The conditions are such we could expect in forest areas rates of spread of 6 – 10 kph (about as fast as it gets), Flame heights of 30-70 metres and spotting up to 30km ahead. In grass lands the max rate of spread of 26 kph will probably occur and fire can be carried over eaten out areas as only a very little dead grass or even burning dried cow pads can be effective for spreading fires under these conditions.
The winds on the charts are showing as North rather than the more usual Northwest in these cases. The wind change is showing up as a west rather than the usual south west. This of course has implications for those around current fire areas.
The high winds will mean that some things that don’t start fires normally become of a much higher risk on Tuesday. Power lines clashing and arcing to trees for example, sparks from vehicles . So we are all prone to fast moving short notice fires. I would expect 100 or so of these throughout the state tomorrow. Most of these are likely to be put out by very fast CFA response but a few of them will get through.
I expect the new Fire Weather Estimates to be out soon and if there is any big changes I will email you again.
Regards
David PACKHAM