What if it’s cloudy?

A lot of eclipse chasers are rightly concerned by the weather forecast for April 8. It’s looking to be cloudy or partially cloudy over fairly large areas of the path.

You’ll likely to fall into one of two groups: you’re either mobile or you’re not. If you are mobile, then by now, you’ve probably already adapted your plans to try to head for areas with a reliable forecast of clear skies - although that is still subject to change with 4/5 days to go.

If you’re not mobile, then this post is for you!

We’re currently in Mexico City, heading up to Torreón on Saturday with a tour group. There’s a planned observation site north of there to which we’re heading. Right now, the forecast for that area is rather mixed. I don’t know whether or not there’s a plan ‘B’. I suppose I could have spent the week bugging the company to share their thinking, but we’re going to try to be relaxed about it and assume that the prospect of a large group of disappointed customers will provide sufficient incentive for them to stay flexible. We’ll see!

Even if we were able to move a little - it wouldn’t be that far, I imagine - there’s still the prospect of cloudy skies. What to do? We’re certainly not abandoning our photography plans, but some adjustment will likely be required.

Cloud Levels

One thing you’ll want to get a handle on for your location is the predicted cloud levels. Many sites, such as windy.com give low, medium and high level cloud forecasts.

If you’re prepared to dig into the data a little deeper, and look at the raw weather data (available via many weather APIs) you can get more granular cloud level forecasts derived from relative humidity levels. Here’s the current forecast for our site in Mexico for Monday:

A few things to consider:

• Low cloud might dissipate during the eclipse if it was formed due to convection - as the Sun is progressively obscured, the heat driving the convection is reduced. However, it’s also possible that cooling may cause some clouds to condense out as relative humidity increases.
• High clouds may be thin and should not fully block the Sun - you might well be able to photograph through them
• Mid level clouds are likely to be the most problematic - they won’t dissipate and are likely thick enough to block the Sun
• 100% thin, high clouds is probably better than 70% thick, mid-level clouds

Unfortunately, our forecast is showing 100% upper mid-level cloud right around the time of totality.

What to do?

High level cloud

You may well be able to stick to your original plan. If you were going to shoot telephoto, then still plan on that.

You shouldn’t change your solar filter or eclipse glasses handling though - even through cloud, the Sun can be bright enough to damage eyes and cameras.

You may need to increase your exposure a couple of stops to account for the filtering effect of the cloud. The best approach remains to use auto-exposure bracketing. This section from our recent webinar, “ Countdown to the April 8 Total Eclipse ”, shows you how to set that up.

If there are high clouds, consider increasing your base exposure by a stop or two - it will require some discretion as cloud thickness will vary from location to location.

Scattered Mid and Low level cloud

In these conditions, you’re a hostage to fortune, hoping for a gap at the right time.

You could make the most of the drama and capture video of the moments ahead of totality. Recording sound would capture the hopes and fears of those around you - particularly if things are on a knife edge in terms of visibility!

Wide angle shots may likely work better than a tight telephoto framing that captures mostly clouds. Also, if you’re not already targeted on the Sun, it may be harder to predict where it might emerge from the clouds - again, shorter focal lengths may help.

100% thick cloud cover

The worst case, for sure. I’m thinking a very different photographic approach might be best.

I’m only traveling with a 100-400mm zoom and a 1.4x teleconverter. In these circumstances, my plan is to remove the teleconverter, zoom out and start trying to take candid shots of the people around us - the human element of the situation is likely to be the most compelling aspect of totality. If I look around and see someone taking a candid shot of me, I’ll know you’ve read this post!

It will still get pretty dark, and wide angle shots would be best for capturing that.

We’ll all have to make the best of it - oh, for those sunny days of August 2017 in Nebraska! Good luck, whatever your plans.