Maybe a usable "newspaper" article?

Bear with me, I'm not a Chemistry major, not Journalism. Also, not sure on the whole jetstream thing, how far/where would the ash actually go?

YELLOWSTONE NATIONAL PARK (AP) – Shortly after 11 AM today, the supervolcano that is Yellowstone National Park erupted.
The damage from this cataclysmic event is said to rival that of the eruption that occurred from the very same volcano around 640,000 years ago. Damage is still being assessed, but it is likely that the US military will be able to reach the source of the explosion for several days. An ash cloud estimated 3 miles high hovers ominously over the site of destruction and expands to the south and east for several hundred miles, covering most, if not all of the states west of the Mississippi River.
More information will be released when it is available to the Associated Press.

Sooo...any suggestions?

You could make an article predicting the food shortages to come across America (and globe) due to the midwest's arable cropland being covered in ash, or something along those lines.