PyroCb in the Northwest Territories of Canada

GOES-15 0.63 µm visible (left) and 3.9 µm shortwave IR (right) images (click to play animation)

GOES-15 0.63 µm visible (left) and 3.9 µm shortwave IR (right) images (click to play animation)

On the evening of 29 July 2014, a small pyroCb cloud was produced by a one of the ongoing fires in the Northwest Territories of Canada. GOES-15 0.63 µm visible channel and 3.9 µm shortwave IR channel images (above; click image to play animation; also available as an MP4 movie file) showed that the pyroCb cloud feature became well-defined on the 00:30 UTC (30 July) image, drifting rapidly northeastward. At that time the fire source hot spot (located near 61.5º North, 121.7º West) exhibited an IR brightness temperature of 338.3 K (red enhancement).

The corresponding GOES-15 10.7 µm IR channel images (below; click to play animation; also available as an MP4 movie file) indicated that the pyroCb cloud feature displayed a minimum IR brightness temperature value of -43.9º C at 03:30 UTC.

GOES-15 10.7 µm IR images (click to play animation)

GOES-15 10.7 µm IR images (click to play animation)

The -43.9º C GOES-15 IR brightness temperature corresponded to an altitude of 23,662 feet (7215 meters) on the Fort Smith, Northwest Territories rawinsonde profile at 00 UTC on 30 July (below).

Fort Smith, Northwest Territories rawinsonde data (00 UTC 30 July)

Fort Smith, Northwest Territories rawinsonde data (00 UTC 30 July)

NOAA ARL HYSPLIT forward trajectories initiated at the location of the coldest GOES-15 cloud-top IR brightness temperature (at altitudes of 6, 7, and 8 km) suggested that the high-altitude smoke would be transported eastward, then northeastward during the subsequent 36 hours (below).

HYSPLIT model forward trajectories at altitudes of 6, 7, and 8 km

HYSPLIT model forward trajectories at altitudes of 6, 7, and 8 km

A composite of Suomi NPP VIIRS true-color swaths during the daytime on 30 July (below) did show an area of dense smoke over much of western Nunavut, which was in agreement  with the transport shown by the HYSPLIT trajectories. The VIIRS image also showed large amounts of smoke being drawn southward along the back side of the deep 500 hPa low centered over James Bay.

Suomi NPP VIIRS true-color composite image for 30 July

Suomi NPP VIIRS true-color composite image for 30 July

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