Got this question via Facebook this week:
Where is all this wind coming from? And when could I expect it to slow down??
Hi – thanks for your question!
Let’s start with the basics about wind. Wind is the movement of air created by, in part, a change in pressure. If the pressure gradient is steep, it can create strong winds. If the pressure gradient is shallow, the winds will be light. In general terms, air wants to move from areas of high pressure to areas of low pressure. How the winds blow can be determined by the positions of the highs and lows over the Pacific and the mainland, the temperature, moisture content and the topography.
In the summertime the wind direction is predominantly westerly along coastal British Columbia and over Vancouver Island, but some weather features may temporarily alter the general pattern.
Winds over the past several days have been the result of a few things, most recently a cold upper low that has swirled around east of the Coastal Mountains. This has created westerly pressure-slope winds, as an offshore ridge held in place off to the west of Vancouver Island. Think of it as two air masses colliding. Neither was really strong enough to move the other out of place so they stayed stationairy with a bit of a tug-of-war with the air (wind) going back and forth. This winds along the west coast of Vancouver Island have blown from the northwest, while around Victoria they have blown in a southwesterly direction. These winds are linked to the diurnal (daily) wind trends that we typically see on the coast.
Diurnal (daily) wind cycle
image from Living With Weather by Owen S. Lange
Winds have been gusty at times as a result of all these factors. Wednesday’s break in the breeze came as the ridge became more dominant, pushing the slow-moving low eastward, but another low is approaching. Thursday will see a cold front push rain onto the coast. It will be windy again in the wake of the front. A brief break is coming again on the weekend, but it’s short lived as another storm brings showers to Vancouver Island as early as Monday.
Wind is a complicated and complicating factor on the coast, but it’s fascinating; and as we know, at times it’s a strong reminder of the power of Mother Nature.
