Forecast confidence is extremely low at this point, but we plan to publish a cloud forecast every other day leading up to the total solar eclipse on Aug. 21.

Whether it’s clear or cloudy will make or break the eclipse-viewing experience.

“Average cloudiness” for a particular location is great to know, but what are the real circumstances going to be on Aug. 21? We know one thing for sure — “average” conditions rarely happen.

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.

Link: More eclipse coverage from The Washington Post

Clouds often pop up along the rest of the path throughout the day simply due to 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 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.

We can begin to assemble some likelihoods from very generalized upper-air and precipitation patterns. We will do a daily update on the national outlook as we count down the days. We will endeavor to give our best take on the situation, but please note our confidence levels are low at this point. They will get higher as we approach the big event.


Forecast notes:

  • Low pressure systems possible in the Upper Midwest and Plains
  • Typical afternoon clouds and scattered showers could limit visibility east of the Appalachians
  • Southwest Monsoon thunderstorms may be a problem for the Four Corners area
  • Morning clouds might eclipse the eclipse in Northern California and the Pacific Northwest

(NASA)

Note: We originally said we were going to publish a forecast ever day. We decided that would be overkill. Instead, we’ll plan on a forecast every other day.