Daniel Y,
I see no reason to argue with your interpretation of weather conditions or the effects on the colonies. As we remember, Reno is higher in elevation than the surrounding region and on the fringe of the blast of artic air coming out of western Canada. The polar air descends into this country, traveling in the quadrant east to south, depending on the steering effects of the west to east jet stream. It's easy to see that your specific weather is erratic with all the variables involved.