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The power of the Pineapple Express

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By Chris St. Clair
Weather Broadcaster
@cstclair1
Monday, February 10, 2014, 7:26

After seven days of cold it is time for a change in this weather pattern. The west has been cold - record breaking cold, in fact. The coldest air in North America has lain from British Columbia to The Great Lakes.  

As this welling of cold Arctic air moderates and drifts eastward, a new weather pattern is evolving into place. It will provide a new track for storms to follow, and perhaps even force the idea of spring into daily discussion. 


RELATED: Snow, freezing rain on tap for British Columbia.


The Pineapple Express is coming. This pattern occurs when a strong area of low pressure develops in the Gulf Of Alaska, just west of British Columbia - at the same time an area of very stable high pressure forms over to the south, centered near California.  

The jet stream becomes very powerful between these two opposite air masses. The entire atmospheric flow in this region aids in drawing great amounts of evaporative moisture from the tropical Pacific. Much of it from as far away as near Hawaii. Hence the term Pineapple Express. 

A river of moisture now flows north eastward towards the west coast of North America. As this current meets our coast, it is forced higher into the atmosphere by topography - the western mountains. When this moisture laden air rises, by nature it cools and condenses. Heavy rains can fall for days at sea level, in the higher elevations it will snow steadily.

That is going to happen for the next several days. 


NOT EVERYONE'S UNHAPPY: Chris St. Clair stopped over in Whistler, one B.C. location where snow is welcomed.


Wait, there’s more to this Pineapple Express story.

This energy continues over the Rocky Mountains and will force the creation of a series of low pressure wave that will bring snow across Alberta, Saskatchewan, Manitoba and further east. This process will also push some milder air over the mountain too. 

With the snow will come a change in temperature, back to the seasonal average, and if we get lucky, something that may have us feel that spring can’t be that far away.


TUNE IN: We're keeping a close eye on this system as it approaches. Follow along on TV.


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