Fire weather Wednesday 16 Dec 2009

From David Packham via Ralph at Licola:

Greetings everyone

Below is another letter from David Packham on the fire risk, or lack of it,
for Wednesday 16 December.

Regards Ralph

The second letter from Willung to Licola for the 2009/2010 fire season.
Sunday 13/10/2009.
Dear Ralph
The recent rain events have greatly lowered the strategic fire risk. The
Ketch- Byram Drought Index (KBDI) has fallen by about 20 mm in the last two
weeks whereas we would have expected it to rise by about 15 throughout the
state. The KBDI is now more average.
The deep litter in the wet forests may be still unusually dry even though
the surface fuels have taken up the recent rain. I do not expect that we
will have any catastrophic fires or even any serious fires for the rest of
2009 or even into the first two weeks of January.
The four-day fire weather forecast is showing an extreme fire weather day
for next Wednesday 16 Dec. Such an early extreme day can be very serious,
for example the Lara fires on 8 Jan 1969 caused 16 deaths, fourteen along
the Melbourne – Geelong Road. However that was a month later and we
currently have significant greenness and useful recent moisture.
The predictions for Wednesday 16 Dec 2009 show an average FFDI for Victoria
of 45 with Tullamarine (my worst case indicator) forecast to be 71 for
forests but only 12 for grasslands. The Victorian FFDI translates to a rate
of spread of 1.6 kph. Flame heights of 26m and maximum spotting of 4.8 km.
The Byram Fire Intensity Index is 24 Megawatt per metre, which is ten times
the maximum for frontal attack and at least twice the maximum survival level
if caught in the fire front. If a major fire occurs the maximum deaths
could go as high as 16 for the State. However at this stage I would
expect that the recent rain and the low curing state would result in a lot
of noise and no major fires. It looks as though some tropical rain may
occur with the change which would return things to normal very quickly.
I expect that with the present sensitivity any even small fires that occur
will be beaten up. It will be essential to monitor Wednesday as it
approaches to detect any worsening or easing in the fire weather that is
being forecast.
If there is no more rain then the second or third weeks in January 2010 may
result in some bushfires if the McArthur Fire Danger Index (FFDI) climbs
over 50. Similar comments may be made for the Grasslands although a sudden
drying or curing could occur in the last week of December.
I notice that the afternoon analysis is including a serious change for the
NE on Thursday with embedded thunderstorms. With the tropical moisture
around it could be serious for those areas with bare soils as a result of
the high fuel levels that were burnt in 2007 and 2009. I hope without any
avidence that the 2003 disaster area have recovered enough to be less
dangerous to high rainfall events.
I do hope Wednesday and Thursday turn out to be without problems as the folk
of Victoria have truly had enough.
Best regards David