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Category Archives: Seasons
How severe has this winter been?
It may not surprise anyone that the average temperature from Dec. 1 to Feb. 29 this season in Madison was 5.67 degrees above normal, with most of that surplus accumulated during an extremely warm December that was 12 degrees above average.
There are other ways to assess the winter severity that are less local in nature. Four times each day we calculate the areal extent of air colder than minus 5 degrees Celsius at 1 mile above the surface using weather data supplied by the National Center for Environmental Prediction. Averaging the four measurements per day together creates a daily value of the areal extent of this “cold pool.” Continue reading
What is “sea smoke” and where is it usually seen?
We recently got a question from a reader who had heard the term “sea smoke” while traveling near Superior on a windy, cold winter day.
Amazingly, sea smoke has a very similar physical origin to the “fog” we often encounter as we take a shower. Sea smoke is an example of a phenomena known broadly as steam fog. Continue reading
What is “black ice?”
The term “black ice” refers to one of two conditions: a new layer of ice on water, which appears dark in color because the ice is transparent and so we see the deep water below, or a layer of clear ice on a roadway, which makes for hazardous driving conditions.
In both cases the ice is not black, but transparent, and therefore shows the color of the underlying surface. Continue reading
When does the last deep-cold spell of the winter usually come?
As we all work to recover from our recent cold spell, the natural question is: Are we done with bitter cold for the winter?
If we use an overnight low temperature below zero as the definition of a cold spell, then 26 of the 45 winters since 1970-71 have seen a cold spell after Feb. 15 — that’s 64 percent of the time. In fact, in 1974, the last below-zero night was not until March 24, the latest date in the last 45 years. Continue reading
Category: Meteorology, Seasons
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What is Groundhog Day and do the forecasts work?
Long before computers, the Weather Channel and the Internet, humans needed weather forecasts. Farmers and sailors particularly needed to know if storms were approaching.
Over time, various folklore forecasts, often in the form of short rhymes, were devised and passed down through the generations. Although memorable, the folklore forecasts are of uneven quality—some good, others bad. Continue reading
Category: Climate, Meteorology, Seasons
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