Page created and maintained by Roger Edwards, Storm Prediction Center
The 2002 fire season in the West was historically devastating. One of those fires erupted in the northern Black Hills, very near Deadwood SD, burning trees through canyons and hillsides on over 700 acres and closing US 385 (the main north-south route through the Hills). Fanned by hot, dry, southerly, and downslope surface winds, the flames reached the edge of Deadwood and forced the town's residents and tourist-packed casinos to evacuate. With fire directly on the doorstep and dense smoke billowing overhead on southwest winds (just off the surface), it appeared as if the town could go up in an inferno. Just in time to spare Deadwood, a cold front hit with brisk northwest winds, shifting the most threatening fire edge away from town and dispersing the smoke pall back into the hills.
Particles in the smoke plume of the Deadwood fire were large enough to be detected by the Doppler radar from Rapid City; and elements of the plume can be seen streaking off to the northeast from the source fire (located near Deadwood). The part of the smoke plume sampled by the radar beam was in southwesterly flow just above ground level until the front hit.
In loops of the radar imagery, the front was first evident as a thin blue arc that formed near the junction of the Wyoming, Montana and South Dakota borders, spreading southeastward for a brief time. It then appeared to vanish (but just couldn't be detected by radar) for a brief time, until it plowed through the smoke plume. The smoke was spread southeastward through southwestward when hit by the cold front. Soon after frontal passage, the next available station observations showed the front as falling temperatures and winds shifting around to the northwest and strengthening. [See the image legend for an explanation of the features on the map.] The front then surged southeastward across the rest of the region, evident in the loop as a long arc of blue reflectivity.
Much of the expansion of blue echo north and northeast of Rapid City wasn't smoke, but instead, is return from particles of many kinds and from insects, trapped under the inversion of stable air atop the frontal cold pool.