Meteorologist discusses effect of different types of precipitation on ag soil
For producers across the West and Midwest, this winter has been everything but mild. Many have battled frigid, below-zero temperatures and varying precipitation depending on location.
In an episode of Kansas State University’s (KSU) Agriculture Today podcast, dated Jan. 20, KSU Meteorologist Chip Redmond discussed various types of precipitation seen across the U.S. the past few weeks and the lingering effects it will have on agriculture land in weeks to come.
Location determines weather patterns
To begin, Redmond points out high and low pressure systems, dependent on location, play a huge role in weather patterns. He notes southeastern areas of Kansas received freezing rain last week, while areas north and west – in and out of the state – mostly saw snow.
“In Kansas, we have a systematic, normal process we call a mid-latitude cyclone, which is a synoptic scale, low-pressure system where wind spins counter clockwise, which wraps warm air from the South – usually the Gulf – northward, so the warm air rises,” he explains.
This also occurs with cold air, which comes from the North and the East and wraps around westward, according to Redmond. This causes air masses to spin around each other at various heights in the atmosphere, which dictates the kind of precipitation that will fall.
“Kansas sits south and east of the low pressure zone in a warm weather sector. We are south of the warm front and east of the cold front, so we were the warmest compared to other areas, and we only saw rain,” Redmond says.
“As we move further north, we cross the warm front and get into a colder air mass at the surface, usually resulting in mixed precipitation. As we move out to the West, we cross the cold front where there is a much deeper mass of cold air, and those areas saw snow,” he adds.
Types of precipitation
Redmond notes the type of precipitation an area will see largely depends on the temperature of these air masses.
“We will start with rain. Rain is cut and dry,” he states. “As precipitation falls from a cloud, it accumulates into water droplets or ice. It gets heavy enough to fall, and gravity pulls it down through a thick layer of warm air where it melts into a raindrop. And, since it’s warm – above 32 degrees Fahrenheit – all the way to the surface, it hits the ground as a raindrop.”
As the temperature of the air profile from the cloud base to the surface changes, so too will the type of precipitation, Redmond says.
In fact, a thin layer of air, at or below 32 degrees Fahrenheit, sitting on the surface with warmer air above it all the way to the cloud base will result in freezing rain.
In this situation, Redmond explains precipitation will fall through the warm layer as a water droplet. When it hits the thin, cold layer, it won’t have time to refreeze, but if the ground is cold enough it will freeze on contact.
He notes this combination of conditions is hard to come by, which is why freezing rain doesn’t occur very frequently.
“If the layer of cold air is any thicker at the surface, with warm air still above it, the precipitation will refreeze in the cold layer and fall as sleet,” he says. “Sleet is typically clear, compared to graupel which is cloudy and looks like hail. They are two different things, created differently based on buoyancy and turbulence in the atmosphere.”
Lastly, Redmond explains if the entire air profile from surface to cloud base is at or below 32 degrees Fahrenheit, precipitation will fall as snow.
To conclude his discussion, Redmond shares all of this variability in precipitation may have an effect on agriculture operations in regard to moisture content for agricultural soils.
“Snow is really important for agriculture because it typically melts slowly, which gives moisture a chance to soak into the ground,” he says. “On the other hand, if we get rain in the winter and it falls too heavy and the ground is frozen, it will just run off.”
Additionally, Redmond notes there is large variability in types of snow and how much moisture they contain.
“Say we get 10 inches of snow during a really cold period with below-zero temperatures. It will typically have a lot less moisture in it because cold air can’t hold moisture,” he explains. “Typically, when it’s cold, the snow is soft and fluffy, but it tends to compact quickly when it starts to melt. We can see ratios of as much as 20 inches of snow reduce down to less than one inch of moisture.”
In contrast, Redmond refers to recent snowstorms in the West which left many with nearly two feet of snow.
“Temperatures were around 30 degrees Fahrenheit during these storms, which means the atmosphere had the ability to hold a lot more moisture. This causes a difference in the chemistry, dynamics and moisture content of snowflakes,” he says. “This 24 inches of snow may melt down to three inches of precipitation, which is a lot of moisture from snowpack.”
“However, this thick, heavy snow might have a harder time melting down. It can compact and turn to ice and will probably stick around for a lot longer,” he adds. “It really all depends on the time of year, the type of precipitation and the moisture content of the different types of snowflakes.”
“The most recent precipitation events could have impacts for producers down the road,” Redmond concludes. “The amount of moisture and potential ice and snowpack will have underlying effects on temperatures and precipitation trends over the next few weeks.”
Hannah Bugas is the managing editor for the Wyoming Livestock Roundup. Send comments on this article to email@example.com.