By Boak Wiesner
Knowing that major drop in temperature was imminent this past weekend, I made a point to hie myself out the Arboretum in time to revel in the unseasonal warmth that Mother Nature was predicted to serve up on Saturday morning. And she did not disappoint. While I may not have moseyed around in shirt sleeves, at least no hat nor gloves were needed. Now just 30 hours later, our area is experiencing the coldest snap in four years. And I waited to see just how many degrees from 37 the mercury, well, alcohol, will fall before this thing was done. So far 52 degrees!
This rapid change is actually not an anomaly. Mid-latitude cyclonic systems are common recurring patterns of weather through these parts. First comes some unseasonal warmth, “sucked” north by winds spinning counterclockwise head of the low. Then, whammo! comes the fierce north wind! Incidentally, the low producing this system passed north of us, through Duluth and northern Wisconsin. A current weather map at hand, especially one that indicates the rate of movement, is all one needs to do as well as the folks on the TV at predicting when and what the skies will throw our way.
The striking dichotomy between hillsides facing the sun versus those facing away caught my attention. Towards the north, hills were completely covered by snow while those just across Green Heron Pond had just a thick carpet of oak leaves underfoot. The sun at this time of year never gets much above 30 degrees above the horizon anyway. Considering all the steep hills created by the erosion of glacial moraines that are characteristic of our area, these discrepancies abound. It would be interesting study to examine if there’s enough of a difference over the course of many winters to set speciation in motion.
An aspen tree along my way was another example of prominent dichotomy. The side facing the sun was a mass of broken cork while the opposite side was yet the smooth grey bark of younger aspen trees. If one did not know it to be the same tree, it would appear to be two completely different species.
The warmth of the morning softened the snow just enough to let that half-pound of sheer exuberance, better known as a red squirrel, leave these very clear tracks. Not just a few oak trees along my walk showed middens at their bases, that is, mounds of acorn leavings, husk and tops, that are the remnants of many a squirrel meal in the same spot. Like us, even squirrels have their favorite “restaurants.”
Boak Wiesner is a Minnesota Naturalist volunteer.