Forecast notes as of Aug. 3, 2017:
Forecast confidence: Very low
- Low pressure potential still exists in the Northern Plains states into the Midwest. The timing and placement of this low pressure is still a major question mark, so things could change as we move closer to the date.
- Typical afternoon clouds and scattered thunderstorms may limit the Southeast and the East Coast, as well.
- North American monsoon clouds and scattered thunderstorms could be a viewing problem in the Southwest.
- Morning fog is likely on the West Coast. The question is whether it will burn off in time for the eclipse.
The timing of the eclipse is ideal, at least for the West. It begins just before 11 a.m. local time on the West Coast, which is usually enough time to burn off the fog that can often occur out there.
The intermountain areas typically see thunderstorms bubble up in the afternoons during this time of year. These are associated with the Southwest monsoon, a period of increased thunderstorms and rain during the late summer and early fall. But the eclipse passes through this region around noon, so it should beat the worst of that threat.
Clouds often pop up along the rest of the path throughout the day simply because of warmth and moisture. Those two things combined lead to rising air, which creates clouds. So the cloud risk gets greater the farther east you go. On top of that, South Carolina will see totality the latest in the day — after 2:30 p.m.
Obviously the eclipse is still too far away to get a good forecast. But some of the forecast models we use to predict the weather go out several weeks, and at this point, they cover the day of the eclipse.