Your friend is right. The most basic predictor of temperature is the "thickness" of the atmosphere. If its thick over you, you're in a big ridge. If its "thin" you're in a big trough. Ridges are warm; troughs are cold. I don't mean just a surface high or low pressure area; I mean though the depth of the atmosphere. The pattern of troughs and ridges through the depth of the atmosphere is a relatively slowly moving pattern and in the summer can get "blocked" or fixed into place for days or weeks. For the last 2 weeks we've had a big ridge over the center of North America; particularly strong (or thick) over the central US. Its been blocked. Now the models are shifting the ridge to the west and locking it in place for the next week or 2 over the US Southwest. That means, for BC, the flow will become from the southwest through the depths of the atmosphere, and prevent those pesky, cold, gulf of Alaska lows from dropping on you every few days like they have all spring. It will warm up quite a bit and stay that way for a week or, likely, longer. Of course, that means that the thickness of the atmosphere will drop over the East. Not much, though, which is why I don't think the pressure on power generation in the US will fall off much thru the third week of the month. CJ