From Wikipedia:
The Chinook in the Pacific Northwest
The term Chinook Wind is also used in British Columbia, and is the original usage, being rooted in the lore of coastal tribes and brought to Alberta by the fur-traders. Such winds are extremely wet and warm and come from the southwest, and are also known as the Pineapple Express since they are of subtropical origin, roughly from the area of Hawaii. The air associated with a west coast Chinook is stable; this minimizes wind gusts and often keeps winds light in sheltered areas. In exposed areas, fresh gales are frequent during a Chinook, but strong gale or storm force winds are uncommon (most of the region's stormy winds come when a fast westerly jet stream lets air masses from temperate and subarctic latitudes clash).
Typically a weather forecaster in Vancouver might say "the Chinook is going to last for another five days, so expect heavy rain for the next week. The mountains [i.e. for skiing] will be rainy to the alpine, so expect lots of slush on the slopes." When a Chinook comes in when an Arctic air mass is holding steady over the coast, the tropical dampness brought in suddenly cools, penetrating the frozen air and coming down in volumes of powder, sometimes to sea level. Snowfalls and the cold spells that spawned them only last a few days during a Chinook, as the weather blows in from the southwest. The snow melts quickly and is gone within a week.
The effects on the Interior of the province when a Chinook is in effect are the reverse. In a rainy spell, most of the heavy moisture will be soaked out by the ramparts of mountains before the air mass reaches the Canyon and the Thompson River-Okanagan area. The effects are similar to those of an Alberta Chinook, though not to the same extreme, in part because the Okanagan is relatively warmer than the Prairies, and because of the additional number of precipitation-catching mountain ranges in between Kelowna and Calgary. When the Chinook brings snow on the Coast during a period of coastal cold, bright but chilly weather in the Interior will give way to a slushy melting of snow because of the warm spell more than because of rain.
The term Chinook Wind is also used in British Columbia, and is the original usage, being rooted in the lore of coastal tribes and brought to Alberta by the fur-traders. Such winds are extremely wet and warm and come from the southwest, and are also known as the Pineapple Express since they are of subtropical origin, roughly from the area of Hawaii. The air associated with a west coast Chinook is stable; this minimizes wind gusts and often keeps winds light in sheltered areas. In exposed areas, fresh gales are frequent during a Chinook, but strong gale or storm force winds are uncommon (most of the region's stormy winds come when a fast westerly jet stream lets air masses from temperate and subarctic latitudes clash).
Typically a weather forecaster in Vancouver might say "the Chinook is going to last for another five days, so expect heavy rain for the next week. The mountains [i.e. for skiing] will be rainy to the alpine, so expect lots of slush on the slopes." When a Chinook comes in when an Arctic air mass is holding steady over the coast, the tropical dampness brought in suddenly cools, penetrating the frozen air and coming down in volumes of powder, sometimes to sea level. Snowfalls and the cold spells that spawned them only last a few days during a Chinook, as the weather blows in from the southwest. The snow melts quickly and is gone within a week.
The effects on the Interior of the province when a Chinook is in effect are the reverse. In a rainy spell, most of the heavy moisture will be soaked out by the ramparts of mountains before the air mass reaches the Canyon and the Thompson River-Okanagan area. The effects are similar to those of an Alberta Chinook, though not to the same extreme, in part because the Okanagan is relatively warmer than the Prairies, and because of the additional number of precipitation-catching mountain ranges in between Kelowna and Calgary. When the Chinook brings snow on the Coast during a period of coastal cold, bright but chilly weather in the Interior will give way to a slushy melting of snow because of the warm spell more than because of rain.
I love the Chinooks. It is one of the best weather events we have in the Northwest. Everyone has been waiting for it, and this one is long overdue. But today I stood outside and smiled in the wind listening to the snow melt run like a river.
So, for the last two days, and hopefully for a few more, the temperature is above freezing, the wind is blowing, and the rain is helping them melt the snow. We have had about 5 feet, now down to about 3. The valley melting is causing floods. The main roads are finally clear of snow and ice; just wet pavement now. Up here on the hill there is alot of ice on the road and the driveway, but it will be gone as well if this keeps up for a few more days. The heavy load of snow slid off the barn roof this morning, now there are 10 foot high mountains of packed snow turning the lean tos on each side into tunnels. The boys came by and shoveled the roof of the house one more time, and the icicles that reached the ground on Monday are gone. There is damage, we can see it now as the snow disappears.... some flashing down, a couple of broken support beams, quite a bit of fence is torn out. We won't be able to get to that for quite sometime since there is still hip deep snow out there. The horses and mules are sissies, so I'm not worried that they will go through the downed spots. They are all happy to stand in the new tunnel the snow made today, out of the wind and rain, waiting for one of us to slip and slide to the barn to feed 'em.
I will be out there again tomorrow, smiling in the wind. I will always marvel at the wonder of the experience of the Chinook Wind.
