Lethbridge is chinook country. This page reads the last 20 hours from our West Lethbridge station and looks for the signs of a chinook: a fast warm-up, a west wind and falling pressure.
A chinook is a warm, dry west wind that comes down the east side of the Rockies. Air loses its moisture climbing the mountains, then warms quickly as it sinks onto the prairies. In winter it can push the temperature up by 20 °C or more in a few hours and melt snow almost overnight.
Lethbridge sits close to the mountains and right in the path of these westerlies, which is why it is one of the windiest and most chinook-prone cities in Canada.
The chinook arch. A band of clear blue sky over the mountains with a sharp edge of cloud above it, stretching north to south. It often shows up before the warm wind arrives.
Big swings. Southern Alberta holds some remarkable records. In January 1962, Pincher Creek warmed by about 41 °C in one hour when a chinook arrived.
Wind. Strong gusts, often from the west or south-west. Watch for crosswinds on the highways.