Is winter over in Denver? Our flowers think it’s spring already

3 min. read
Spring status as of March 6, 2017, according to computer models and citizen reports. (National Phenology Network)

This week is once again expected to bring Denver's high temperatures into the 70s. March typically is the city's snowiest month, but these surges of heat have us asking: Is spring here?

Well, let's look at it a couple ways: the behavior of plants and the predictions of forecasters.

Plants think it's spring, and that's worrying:

Spring plants already are flowering, with lilac buds emerging and the yellows and purples of the crocus flowers already in full bloom, according to Dr. Anna Sher of the University of Denver.

For the crocuses "to be already finishing blooming at the very beginning of March is certainly unusual," she told Denverite on Monday morning.

In fact, data from the National Phenology Network indicates Denver's plants are blooming up to three weeks ahead of the average for 1981-2010. NPN collects reports on the status of plants around the country and combines them with weather data to create models of where spring has sprung.

Spring status as of March 6, 2017, according to computer models and citizen reports. (National Phenology Network)

As you can see, Denver's right in there with the glob of early spring that has spread across the South and Southeast. This is a signal of a warm winter -- and part of a century-long trend, according to Sher.

"The fact that the temperatures have been warming on this planet, and the implications for the timing of spring are well-documented and well-known by scientists," she said. "... For many flowers here in Colorado, we’re seeing plants blooming almost a month earlier now than a hundred years ago."

Her team knows this because they've been examining archives of dried and meticulously logged plants that go back many years. (Read more about that method here.)

This early bloom can be harmful for plant life. Though it's getting warmer earlier, the date of the last frost hasn't changed nearly as much, Sher said. As a result, these early bloomers might be hurt or killed by cold temperatures. Changes in the schedule also can throw pollinators, such as bees, out of sync. Net effect: disruption of the ecosystem.

What the weather folks say:

March historically is Denver's snowiest month, according to Weather5280's Brendan Heberton. So, we might expect based on the past to see another storm or two before it's over.

Heberton is doubtful, based on weather modeling, that we'll have snow in the next 10 to 15 days -- but there is indeed a chance some will arrive on a front around March 12 to 14, he writes.

The mountains are still getting a steady series of storms, including one that just put 10 inches at Purgatory and may deliver several inches to the central mountains, OpenSnow reports. OpenSnow agrees that we may see some kind of snow or storm event mid-way through this month.

The plains could badly use precipitation of some form, as Denver and points east are in moderate drought.

What are you seeing at home? Has this weather changed your gardening plans? Are your bushes going crazy? Email me.

Snowshine. (Kevin J. Beaty/Denverite)

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