Lilac weather

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Lilacs in full bloom at the Huttner Weather Lab today.

Even lilacs have a story to tell.

Phenology is the science of watching plants and animals react to weather and climate.

Numerous studies have shown that everything from lilacs to robins are reacting to shorter winters and earlier springs. In the West, lilacs are blooming up to 2 weeks earlier than they did a few decades ago. This rapid springtime warm-up is also linked to evaporation of mountain snowpack before it has the chance to melt and runoff into rivers. This spring runoff is the lifeblood of western rivers like the Colorado, which supplies water to millions in the southwest. Anything that reduces winter snows and spring runoff poses problems for water supplies in places like Phoenix, Tucson, Vegas, San Diego and Los Angeles.

Local phenologist Jim Gilbert has charted lilac “peak bloom” at the Minnesota Landscape Arboretum for decades. According to Jim’s Nature Notebook, this week is peak lilac bloom time. One look around and you can see why. The thing is that’s about two weeks earlier than it was 40 years ago.

One thing that may be tougher to change is ice out dates in Minnesota. In some ways, ice out is more dependant on sun angle and wind than temperature. This year lakes were ice free as of about April 13th in the metro. That’s about average. Even the stubborn ice in Minnesota’s Arrowhead was gone by May 15th.

It’s interesting to observe the changes over the past 40 years. Have you noticed changes in your back yard?

PH

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