HIGHFIRE RISK PROJECT
Prof. Jason Sharples, University of New South Wales, Canberra;
Adj, Prof. Rick McRae, University of New South Wales, Canberra (previously with the ACT Emergency Services Agency)
VLS IN ACTION
We discovered VLS in post-fire analyses of the 2003 ACT fires. It turned out that something new to science was the key driver of events of 18 January 2003.
By doing the science we explained the process, based on data from: observations; modelling; and wind tunnel tests.
Observations were mainly from static imagery: from cameras, satellites, or radar. Any videos were from outside the plume - doing otherwise was probably a fatally bad thing to do.
9 September 2024 at Santiago Peak, CA
The peak is a communications site. There are four camera on it as part of the HPWREN project. They recorded time-lapse vidoes of remarkable fire activity.
Here is a subset of the original HPWREN video:
The wind is easterly, blowing away from the camera (which is a wide-angle set-up). The VLS event pushes the plume base sideways in the lee-slope eddy wind at the top of the main slope. As it goes you can follow the dense, black plume (which is diagnostic of VLS). As the plume blow downwind, it starts a dense field of spotfires. If they are in the eddy, they move towards the camera. If not they blow away from the camera. Eddies appear to land as the plume touches the landscape downwind - up to 2 miles away.
Note the plume top - it hits an inversion spreads out sideways. Perhaps there were towering pyroCu clouds above, but we can't see.
With that convective cap it is feasible that it was a foehn wind event, which in California are called Santa Ana winds. Santa Ana itself is just west of the fire. We have confirmed VLS involvement in foehn effect fires in south-east Australia. These involved isentropic drawdown.
10 September 2024 at Santiago Peak, CA
The next VLS occurred the next day on the next ridge upwind of the cameras. The west-facing camera caught the inside of a VLS event in spectacular detail. A number of fire aviation assets can be seen and towards the end the camera lens gets coated in purple fire-retardent foam!
See also...
A CNN story on this fire
METADATA
Santiago Peak is at: about 33.71,-117.53 at 5669 feet. See Map .
This is the second major fire captured in HPWREN videos on this hilltop. In both instances telecoms staff drove up to protect the site (successfully it seems). Bravo!
See the website of the HPWREN project .