18 September 2007

Gulf country fires

Large bushfires were noted by the media today in far northwest Queensland, west of Burketown. The reports indicate that the large portions of two cattle properties were burned out.

About 10,000 hectares of grazing property in the southern Gulf region of far north Queensland has been scorched by a massive bushfire.

A number of small fires in a region known as Hell's Gate, near the Northern Territory border, have merged to form a large fire currently burning on several fronts, a Queensland Fire and Rescue spokeswoman said.

These fires were first noted at Australia Bushfire Monitor in their incipient stage back on 12 Sep in the post “NT/QLD border fires”. Comparing the NAFI image from the afternoon of the 18th (about 3pm, below) with the previous image, the fires have grown quite considerably, especially those on the QLD side of the border. The NAFI image shows two close, but distinct regions with fire scars and/or hotspots in QLD. The westernmost one, the fire being report is roughly 130 000 ha bunt. The eastern fire is on the order of 175 000 ha

While these fires are large and serious, the true 'monster' out there are the fires ongoing across the border in NT. These fires have undergone a massive flare-up today. This fire has also expanded considerably since the previous update and estimates from NAFI now suggest that nearly 500 000 ha has been affected.

A smaller region, about 75 000 ha, near Billengarrah, NT is also active at this time.

The 500-m resolution true color MODIS browse image from the 0425 UTC overpass of the Aqua satellite is shown below. A massive smoke plume is observed in association with the easternmost NT fire. A relatively small (by comparison) smoke plume is seen with the QLD fires.

Why the flare-up? I have to say that I am at a bit of a loss as to the answer to that question. Observations at nearby stations from this afternoon suggests light winds, on the order of 10-20 km/h. Temperatures in the upper-30s. Humidity was a bit low, near 10% in the afternoon, but it doesn't seem particularly unusual compared to previous days. These observations suggest a GFDI on the order of 5, in the moderate category, while FFDI (although it is not forest) of around 30, in the very high category. Still, why today and not, say, yesterday? Is the non-linear response to slightly lower RH that severe?

There were fire bans issued further east in the NT today, in the Alice Springs and Katherine districts.

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