Farmers across Wisconsin are looking for a bit of a break this year when it comes to precipitation. According to Timm Uhlmann, meteorologist with the National Weather Service in Green Bay, the odds are the state won’t be in for another record-breaking year in terms of precipitation.
Unfortunately, that doesn’t necessarily mean a return to normal, he said.
Green Bay has had two record-breaking wet years in a row, Uhlmann said. The 30-year average rainfall in the area is 29.5 inches. In 2018, Green Bay set a record with 39 inches, and 2019 broke that with 48 inches.
“It’s been a wet couple years for Wisconsin, for sure,” Uhlmann said during a March 2 webinar “Weather forecasts: How are they made?” presented by UW-Extension Discovery Farms. “But it’s very unlikely this will set the standard for every year running. We broke the record two years in a row, but the odds of that happening again are less than 1%.
“Which isn’t to say we won’t be above normal again, but the odds that we get near that record again are unlikely. But it is important to acknowledge how abnormally wet it has been.”
Uhlmann pointed to three month outlook maps by the National Weather Service’s Climate Prediction Center that show eastern Wisconsin with a greater chance than the rest of the state of seeing above average temperatures over the course of the next three months and the entire state having a chance of above normal precipitation in that same time span.
“This has been predicting a warmer and wetter spring than average,” he said. “This past year was very harsh on the ag community. Unfortunately, through summer, they are expecting wetter than average. But that doesn’t mean there won’t be dry weeks in there as well.”
Uhlmann said climatology summaries show that the average annual precipitation and temperature trends in Wisconsin have been on a gradual increase.
“But that is a climate trend,” he said. “Just because it’s been wetter and warmer as an average doesn’t mean that we can’t see drought or that we won’t see cold days.”
The National Weather Service is part of the National Oceanic and Atmospheric Association under the U.S. Department of Commerce.
The primary roles of NOAA are research and data gathering, and the NWS is the branch of that tasked with issuing watches, warnings and advisories based on weather as well as providing weather forecasts that are updated twice a day, collecting weather and climate data, conducting outreach and research and relay weather-related information to communities.
Wisconsin’s 72 counties are covered by five offices of the National Weather Service.
Uhlmann explained that the weather is what’s happening outside your window right now, while climate is a statistically derived average of what has been seen in the past, and the past 30 to 40 years make up what is considered “normal.”
“Weather and climate are connected. Long-term weather creates what the climate is, but the weather can be very different,” Uhlmann said. “One of the common misconceptions is that you can use one single weather event to define climate.”
Uhlmann said slight errors in computer models and limited surface, atmospheric and satellite data can accumulate, making long-term forecasting difficult.
“A Day 3 forecast relies on what you said happening in Day 2 coming true, which relied on Day 1 coming true,” he said. “If any one of those is off, you start getting further and further off.
“It’s physically possible to give a forecast that’s 50-days long, to run the models out that far and to come up with something that is reasonable from a climate stand-point. However, whether or not it actually comes true is unlikely. Every single day, you’re accumulating a little bit more error.”
Uhlmann said localized events like dry air moving in, causing clouds to evaporate, can have a big effect on overnight lows in late fall and early spring. That would then lead to an adjustment in the following day’s highs, but that adjustment is not always necessary, he said.
“This happens in the hours right before sunrise in areas of north-central Wisconsin, where temperatures will plummet 20 degrees if they clear out just a little bit and a couple hours later, they’ll recover,” he said. “The models typically don’t handle that well. It’s a chance for the local forecaster to know these things are coming up.”
Uhlmann’s webinar was part of Discovery Farms’ webinar series aimed at unmasking misconceptions in weather, water quality and on farm management strategies. The series runs Mondays in March from noon to 12:50 p.m. Archived versions of the webinars are available at www.uwdiscoveryfarms.org.