Will Clouds Spoil Your Total Solar Eclipse Viewing Party?

A box arrived from NASA last week. It contained special glasses for viewing the upcoming total solar eclipse. In case you missed it (and not sure how that is possible at this point), a total solar eclipse will move across North America on April 8. It’s not that I am a psychic, but I know some people are wondering if clouds will obscure their view of this rare occurrence and spoil the total eclipse party.

The excitement of this total solar eclipse sends me back to 2017 when we organized a massive solar eclipse classroom at the University of Georgia. As the brainchild of my colleague Dr. John Knox, iconic Sanford Stadium was opened to the public for a day of lessons about solar eclipses, weather and more. It has been estimated that tens of thousands of people filled the stadium that day. Even though Athens, Georgia was not in the path of totality (we were close), it was still a spectacle and an amazing day of learning. Unfortunately, we are not as close this time around.

Why does a total solar eclipse occur anyhow? According to a National Weather Service website, “A solar eclipse happens when the Moon passes between the Sun and Earth at just the right moment.” If all of the sun’s light is blocked, it is a total solar eclipse. The website goes on to say, “As the Moon blocks the Sun’s light, it casts a shadow on part of the Earth.” That shadow will track across the landscape as Earth rotates beneath it. Though nothing compares to being in the path of totality, it is still fascinating to see from any vantage-point, but please wear the special glasses.

April is a transition month for weather and that could mean cloudy or even stormy conditions. Is there a way to see what the tendencies are for cloudy cover on that date? Yes, they are called climatologies. Matt Gunshor wrote an excellent post on cloud climatologies on the CIMSS Satellite Blog. He points out that some climatologies are derived exclusively from satellite data while others may be comprised of different types of data.

NOAA maintains two geosynchronous satellites (GOES EAST and GOES WEST) to provide continuous observation of clouds, lightning and other weather phenomena. The climatology map above is made exclusively from GOES weather satellites. It reveals the mean cloud fraction on April 8 spanning the period 1995 to 2023. It tells you something about probability, but Gunshor cautions, “Disclaimer on cloud climatology: this is not a real forecast and past clear or cloudy skies do not guarantee anything for April 8, 2024!…. check your local forecasts which are probably starting to get pretty accurate for clouds around April 6 and will be most accurate the morning of the eclipse.”

Which brings me to another point. I am writing this very early on the morning of March 29. That means that we are still 10 days away from the event. Yet I am seeing very definitive forecasts about the prospects of cloudy conditions based on long-range weather models. Don’t fall for the social “media-rology” predictions right now. At 10 days out, we are still at about the upper range of skillful weather forecasts.

Legendary scientist Edward Lorenz and his discussions of chaos theory signaled decades ago that there was likely an upper limit on weather predictability. A 2019 study out of Pennsylvania State University found that limit to be within two weeks and probably around the nine- or 10-day mark.

My colleague Dr. Kim Klockow-McClain is a senior social scientist at the University Corporation for Atmospheric Research and supports the National Weather Service. She wrote on her Facebook page, “We’re well out in forecast lala land right now with a pattern that makes specific predictions for any particular point in time very dicey, so just deep breaths everyone.”

I will close with a fun fact about solar eclipses and clouds. The eclipse might actually dissipate clouds and reduce temperatures. Some convective clouds are related to land surface heating. As the NASA Earth Observatory website notes, “As the Moon blocks the light from the Sun, the convection process is reduced, resulting in cloud dissipation or the disappearance of clouds.” Clouds caused by stronger atmospheric processes like fronts or large areas of low pressure are not likely to be as affected, but a cute little cumulus cloud might be. You can actually be a citizen scientist and help the GLOBE program by participating in their Eclipse Challenge: Clouds and Our Solar-Powered Earth.