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August 2005 Wildfires
School Fire over the Northern Blue Mountains
06-07
Aug 2005
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After a few
weeks of hot and dry weather over the inland northwest, the fire season
was beginning to swing into full gear. Of special interest was the "School
Fire", located over the northern Blue Mountains or nearly 100 miles
south of Spokane.
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Although this
fire was nearly 100 miles south of the Spokane area, its affects could
be easily viewed across the southern celestial dome. The heat from the
fire was sufficient to lift the air to great heights which resulted
in the formation of a pyrocumulus cloud. A pyrocumulus cloud forms if
there is enough moisture and atmospheric instability over the intense
heat source. Although not common, these clouds can grow large enough
to produce lightning and possibly some light precipitation.
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The combination
of smoke and moisture was detected by the Spokane radar as noted in
the image composite to the right. The heights of the radar returns are
denoted in pink for each slice of the radar scan. The bottom left panel
detects some returns or echoes above 37,000 feet. Values this high are
often associated with thunderstorms. Despite this fact, the local lightning
detection network depicted no nearby cloud-to-ground lightning strikes.
The picture in the upper left corner shows some radar returns in excess
of 40dBz (yellow pixels) at an elevation of 11,500 feet. These values
are often sufficient for light precipitation reaching the ground, however
the NWS office received no reports of ground precipitation.
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The animation
to the right is of the visible satellite imagery from approximately
500 pm until 630 PM At least four fires could be detected on this loop,
although the North Fork Fire (near Yakima) was rather faint. Even from
22,300 feet above the earth, the School Fire looked very impressive.
The smoke column from this fire exhibited obvious vertical development
(notice occasional blue enhancement and shadows on the ground and downwind
smoke shield). By the last frame in the animation, this plume had spread
as far as the Prospect fire, or nearly 140 miles to the east.
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So what did
this column look like from the ground? Although the bulk of the plume
skirted by Lewiston, a couple of webcam images gave some clue.
The left image, taken at 331 PM, showed little signs of smoke. However,
by 511pm, the skies darkened and an ominous layer of black smoke was
noted at the top of the picture. This smoke hung around through much
of the evening and even as of 10 pm...a nearby weather sensor was still
detecting a layer of smoke over Lewiston.
Images courtesy of KLEW-TV
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The large School
fire continued burning through the night of August 6th and into the
morning of the 7th. By morning, the fire (combined with others in Montana)
had spread a massive shield of smoke as far east as North Dakota. The
image below is a high resolution picture captured by the same satellite
utilized in the animation previously depicted above. The smoke shield
is delineated by the green arrows.
Image courtesy of the National Weather
Serivce's Satellite Services Division.
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Webmaster
US Dept of Commerce
National Oceanic and Atmospheric Administration
National Weather Service
Spokane Weather Forecast Office
2601 N. Rambo Rd.
Spokane, Washington 99224
Tel: (509) 244-0110
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