RMulhern,
I think either the article mistated or you misunderstood. The edge of the crater probably wouldn't be past Cody, if that far. The edge of the ash cloud would easily reach Minnesota. The theory is that the ash and gasses in the atmosphere would reflect so much sun light that it would cause a "nuclear" winter situation.
As the article states, the landscape in Yellowstone is always changing. The dome under yellowstone lake keeps rising and falling and the one under Norris Geyser basin is just as active. Hundreds of small tremors vibrate the area all the time and occasionally a jolt big enough to feel will hit. Thermal features stop and start with all of this geologic activity. There are many places in the park where pavement has opened up from below and steams constantly. Walking off of the boardwalks in the thermal areas is a BAD idea.
