We had a very interesting terrain-driven weather pattern last night. You may have wondered why Bogus Basin didn’t get any snow but Boise did?
No snow at Bogus Basin, but snow on foothills and in Boise.
An arctic cold front moved across the region from the Northeast as a low pressure moved across the area into southern California. When this happens air cannot easily get over the Rocky Mountains so it goes through the paths of least resistance, hence it moves in from the northwest via Hells Canyon and Baker Valley in NE Oregon and from SE Idaho via the Snake River Plain.
Low Pressure moving into CA allowed cold air to set up convergence zone in Treasure Valley.
Air in the lowest levels of the atmosphere collided, creating what we call a convergence zone. Terrain-induced northwest winds collided with southeast winds near Boise and Mountain Home, causing lift. This lift essentially squeezed the moisture out of the air…much like wringing water out of a wet cloth.
Radar Imagery: Southeast winds collided with northwest winds causing a convergence zone along the Boise foothills to Mountain Home east to the Camas Prairie. Areas in blue and green indicate snow.
Bogus Basin was not subject to the convergence zone as the Boise foothills acted like a barrier, keeping the convergence zone in the Treasure Valley. The areas where the snow-cover were visible on the MODIS imagery. Notice the swath of snow along the Boise foothills, east Boise, and areas east of Lucky Peak and north of Mountain Home.
MODIS Imagery showing snow cover on the afternoon of 2/22/2015
