You are probably well aware that the haze in the sky this past week was the result of smoke from wildfires out west, but you might be wondering how it got here. After all, we are about 1,500 to 2,000 miles away from the source. Typically, we’re only worried about what we see at the surface, but a few key components higher up in the atmosphere ultimately determine the weather that we see at the surface. The main one is the jet stream, which has the fastest winds aloft and is found several miles up in the atmosphere. In general, it divides cold, drier air to our north and moist, warmer air to our south. Ultimately, the jet stream steers our storm systems. It blows from west to east across the United States with some north and south bends in the flow. As smoke rises, it can get caught up in this jet stream and transported large distances.
Below is an image from NOAA’s Global Systems Laboratory showing the movement of smoke across the United State according to a high-resolution forecast model last week. I made a couple of edits, one showing the source of the smoke from the wildfires out west and another showing the flow of the smoke across the United States (blue line). This blue line followed the same path of the jet stream at the time, which for comparison purposes can be seen in the upper-level map just below. The jet stream ended up directing the smoke northeast into South Central Canada and then southeast into the Ohio Valley Region.