SURFACE WINDS DURING AN INTENSE OUTBREAK OF ARCTIC AIR IN SOUTHWESTERN BRITISH-COLUMBIA

An outbreak of arctic air which occurred from 30 January to 2 February 1989, plunging southwestern British Columbia (as well as most of west ern North America) into extreme cold, is examined and put in context b y reference to similar events reported in the literature. Emphasis is placed on the resulting wind fields in Howe Sound and the Lower Fraser Valley. The wind speed in these topographically confined channels dur ing arctic outbreaks is found to be related to the down-channel pressu re gradient. Three simple steady-state models of wind speed are sugges ted whose results are compared to observed winds. It is found that the Friction model, representing a balance between friction, acceleration and horizontal pressure gradient, compares best with observations in the Lower Fraser Valley. Hydmod, a hydraulic model of wind flow perfor ms reasonably well, with previous work indicating it produces more rea listic along channel flow variability in Howe Sound.