PyroCu in Western Australia

On 14 November there was a pyroCu in Western Australia at 34.6 S 116.7 E. Himawari-8 detected the smoke plume and clouds around the fires, as well as the fire hot spots. Starting at 01:00 UTC on 14 November, the animation below shows visible (.64 μm) on the left and shortwave IR (3.9 μm) on the right (click image to play animation). In the shortwave IR images the darker black to red pixels indicate very hot IR brightness temperatures exhibited by the fire source region.

Himawari-8 0.64 μm visible (left) and 3.9 μm shortwave IR (right) images (click to play animation)

Himawari-8 0.64 μm visible (left) and 3.9 μm shortwave IR (right) images (click to play animation)

Himawari-8 10.4 μm IR channel imagery the minimum cloud-top IR brightness temperatures could be found. The animation below, starting at 04:30 UTC on 14 November, shows that the pyroCu reached around -35 ºC (dark blue color enhancement) around 06:00 UTC. It is hard to distinguish between the clouds from the pyroCu and clouds that are moving into the area. Since it has not reached -40 ºC it is not considered a pyroCb.

Himawari-8 10.4 μm IR images (click to play animation)

Himawari-8 10.4 μm IR images (click to play animation)

Below is an animation of the convergence at 250 mb shown by a color fill, the the 250 mb geopotential height contoured every 30 meters and the wind barbs. It has been investigated that upper level divergence is associated with the ability for pyroCu to turn into a pyroCb (Peterson et al., BAMS, Feb. 2015, 229-247). Starting at 0 UTC on 22 August the spot of the pyroCb is indicated by a white dot. This pyroCb is in an area of divergence. This is conducive to the strengthening of the pyroCb. If there is divergence at upper levels there is rising air below that area of divergence. These conditions are favorable to the pyroCb developing.


250 mb Convergence(color fill), Geopotential Height (contoured every 30 m) and wind barbs every 6 hours starting on 22 August 0 UTC.

This Skew-T taken at 06 UTC on 14 November after the pyroCu located at 34.6 S 116.7 E. From the Skew-T it is apparent that there is a good amount of CAPE which is favorable for convective development. However, there is a very moist layer that could contribute to the fact that this pyroCu never turned into a pyroCb.
skewt11.14austSkew-T at 12 UTC (click to enlarge) Green line is dew point and red line is temperature

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