El Niño and Hot Air Balloons: Your Growing Season Forecast

Read Time: 3 minutes
July 3, 2023
Dr. Zach Hansen
Weather Science Team Manager at Climate

What do you get when you push a big mass of cold air into a big mass of warm air? A thunderstorm. We’ve all heard it before, on our morning or evening weather forecasts: a cold front collides with a warm front. But why? What’s really going on in the clouds that causes these storms to take form? And in light of El Niño moving in, what types of storms can we expect this summer?

What Do Thunderstorms Have To Do with El Niño?

Let’s start with a recap. Last December, we were still experiencing La Niña, with colder weather in the upper half of the United States and wetter weather on the west coast. Earlier this year, it became certain that we were moving away from La Niña, but what was ahead of us was unclear. Now, we can say with full confidence that El Niño is here. And beware, he’s coming in hot. Dynamical models are predicting that we can expect a stronger-than-normal El Niño, likely to continue through the winter of 2023/24.

Let’s talk about what this means for our forecast. In the majority of the United States, we can expect especially warm temperatures, with the Corn Belt being the exception. For those farming in the Midwestern U.S., we can expect around average, if not slightly warmer temperatures. We are also quite confident that we will experience more rainfall than normal, especially in the Midwest–specifically the mid-Mississippi River valley, approximately from the Missouri border and downward. Recent seasonal outlooks have also forecasted relief for the Eastern Nebraska, Western Iowa, and Kansas regions.

Above average rainfall can be expected, especially in the Great Plains and Central Midwest.

But how much rain is too much? The excess rainfall could be problematic in areas like the Ohio River valley, and necessary GDU’s may be difficult to achieve. In general, there is potential for flooding in low-lying areas, as this extra precipitation will likely be enough to be considered severe rainfall. And with this severe rainfall comes–you guessed it–thunderstorms.

Anatomy of a Thunderstorm

Why does more rainfall mean more thunderstorms? Before we can answer that question, I want to introduce two ideas to keep in mind. First, cold air is heavy, and warm air is light. Second, when water condenses, it creates heat.


Warm Air Goes Up

Now, let’s break it down. A thunderstorm is essentially a huge updraft of warm air. Think of it like a big hot air balloon, rising up into the sky. But how do we get an updraft big enough to actually create a storm? Imagine a completely dry environment with one consistent temperature, all the way from the ground up into space. Now imagine an area on the surface that’s significantly warmer than that temperature–a really large surface heating anomaly. Since warm air rises in cooler environments, that warm air rises up like a hot air balloon and creates an updraft.


Moisture Enters the Scene

Now, let’s introduce moisture to our scenario. Below the cloud base, you have something called the boundary layer. This layer of air is an area where the properties of the air are essentially all the same, everywhere–and where water is not being condensed into clouds. Above this layer, we have the free troposphere, where clouds form.


Water Collects

When water condenses above the boundary layer, it gains heat, which in turn creates a temperature difference between the cloud and the air surrounding it. And since cool air is more dense than warm air, the cloud rises as it gains heat.


The Cycle Continues

Because of the moisture and the heat it gains as it condenses, we don’t need to rely on surface heating anomalies to help the cloud rise. We just need enough moisture to create a temperature difference. More rainfall means more moisture, more condensation, more warm clouds rising, and thus, more thunderstorms. At its essence, a thunderstorm is an upward draft of warm air with water around it.

The Good News

While more thunderstorms inevitably have the potential for more crop damage and flooding in some areas, there’s a silver lining to all this extra rain. The pattern has already begun to emerge this year, as seen in the drought levels across the country. As of now, there is little to no drought east of the Mississippi River, which was not the case in November of last year. We can expect drought levels to continue to decrease across the majority of the country, with a few exceptions, as we get further into the year. As always, we’ll do our best to keep you updated as the season progresses, but it’s shaping up to be a great growing season, and the majority of the growing region can expect sufficient rainfall to keep drought at bay.

About the Author

Dr. Zach Hansen is the Weather Science Team Manager at Climate. He has spent nearly three years at Climate, in a variety of roles all centered on weather. In his current role, he and his team work to ensure that weather data is used effectively in predictive models that help growers make a variety of decisions. Zach received his undergraduate degree in Atmospheric Science from the University of Utah, and his PhD in Atmospheric Science from the University of Wisconsin-Madison. Prior to joining Climate, Zach worked as a research scientist at Nanjing University in China, where he examined the life cycles and characteristics of thunderstorms on a variety of scales.