Wisconsin's warmest winter on record sets the stage for an early bloom

 

MILWAUKEE, Wis (CBS 58) - A record number of days (80) and nights (35) above freezing, a whopping 10 record warm lows, and hardly any snowpack had many Wisconsinites thinking spring throughout the winter.

While many folks enjoyed playing golf in February, others noticed maple syrup flowing early, and buds starting to appear weeks ahead of normal.

UWM Distinguished Professor of Geography Mark D. Schwartz, who helped establish the National Phenology Network, tracks the start of spring by observing the state of lilac and honeysuckle buds.

"In the middle of the winter, say like the lilacs that I look at a lot, they're desiccated, they've already swollen which means the plant has already pumped the moisture into it."

Once the buds are swollen or cracked, it puts folks who do observations on high alert as one decent stretch of warm weather could start the leaf out process.

According to the National Phenology Network, which uses thousands of citizen reports, the emergence of leaves is running between two to three weeks ahead of normal across a large portion of the US due to our abnormally warm winter.

This trend may continue for southern Wisconsin as well.

"The longer term forecast for here suggests that the beginning of our spring, as measured by these shrubs, is going to be may be 5-10 days earlier, which would put it closer to the first of April rather than about the 10^th of April which is our typical time."

A stretch of cooler weather near the end of March would slow the progression of this trend, which wouldn't necessarily be a bad thing.

"We usually have frost after what I call this early spring period, but the natural plants are adapted to those. And so what ends up happening is that you get the plant growth earlier, the plants get to a more advanced state, but the frosts are still at this typical time, and then you get this damage."

This is what happened in early spring 2012 when a killing frost in early April severely damaged many fruit crops around the state that had flowered after a record warm March.

While the frequency of early leaf outs is increasing, the timing of a singular damaging frost event hasn't been changing much year to year.

"This is the concern we have going forward. We're still going to have early springs and late springs, but there are going to be more early of these earlier events and more opportunities when things are, in effect, out of sync. The plants are going to be growing and potentially still get zapped by a frost."

Winter is the fastest warming season in the Great Lakes region, and Milwaukee ranks 7^th in the nation when it comes to the increase in very warm winter days. For us, very warm winter days are days warmer than 45° during the months of December, January, and February.

While a warmer winter, especially late winter, can jumpstart the growing process, there are questions and concerns about how much our native plants can handle.

"I think this is the other issue with natural plants is they can't just keep getting earlier and earlier with no end. There is some limit, but we don’t quite really understand what that is. and it's undoubtedly different in different plants."