Pyrocumulus With Las Conchas Fire
New Mexico, July 15, 2011

by John Farley

Although the Las Conchas Fire near Los Alamos has now been largely contained, dryer weather, heat, and wind are cause the fire to burn hotter and smokier along its southwestern perimeter. This caused the formation of a spectacular pyrocumulus cloud (a cumuloform cloud generated by the heat and smoke of a fire) over the fire on July 15. I took all of the photos below from the Las Campanas section of Santa Fe, around 20 miles from the part of the fire that was generating the pyrocumulus cloud. In the first picture, note the formation of a pileus cap on the pyrocumulus cloud:

Before long, the cloud surged upward through the pileus cap and towered very high over the fire:

The towering pyrocumulus cloud became very spectacular, even forming a mammatus like feature on its underside as it spread northeastward:

With time, the cloud spread northeastward farther and farther due to the prevailing winds. Here is a panorama photomerge showing how the cloud spread out:

As of this morning, although the fire is mostly contained, it has reached 150,000 acres. By far, this is the largest fire on record in New Mexico. The main place where the fire is expanding at all is along its southwestern perimeter, the area shown in these pictures. Firefighters expect to keep the fire from spreading southwest of Forest Road 266 in this area, and in all other areas, the spread of the fire has been contained and the main threat is shifting to flash flooding due to rapid runoff as a result of lost vegitative cover, once the monsoon rains return.

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