The Weather Guys

Carrie Hinterthuer shovels the steps of her East Side home on Wednesday. If we can manage two more days with snow in April, we will have placed ourselves in unusual meteorological territory — more days of snow in April than in March. (Photo credit: Amber Arnold, State Journal)

Conversely, of the 15 days with above-normal temperatures, the departure was never larger than 9 degrees. During the month of March we had five days on which snow fell, with measurable amounts occurring on only three of those days.

As everyone probably senses by now, a rather remarkable transition occurred at the start of April. Through the first six days of the month we have averaged 14.3 degrees below normal and the string of double-digit departures seems certain to last at least until Tuesday.

Even with a slight warm up to almost normal at the end of this week, we will still likely be more than 10 degrees below normal for the month by April 15. By the coming weekend, we will be plunged yet again into below normal temperatures for another few days.

In  addition to the cold, of course, we have dealt with accumulating snow on three days this month and a trace of snow on another. If we can manage two more days with snow in April, we will have placed ourselves in unusual meteorological territory — more days of snow in April than in March. Also worth noting is that in Madison the temperature has not reached 60 degrees since Dec. 4 — which strikes us as an unusually long streak though we have no easy access to the data required to verify that.

Nevertheless, among the many consequences of this prolonged cold at the start of spring is that when it finally does warm up that transition will seem very sudden and the seasonal warming is not likely to suffer a relapse.

Sitting nearly in the middle of the vast North American continent, Madison has what is known as a continental climate. Continental climates are characterized by large annual extremes in temperature and humidity as well as very distinct seasons.

The continental nature of Madison’s climate is what makes a year’s worth of weather in Madison usually a lot more varied than a year’s worth in Seattle, for instance. There is an astounding 144 degrees difference between the all-time highest (107 on July 13, 1936) and all-time lowest (-37 on Jan. 30, 1951) temperature in Madison.

In addition, the amount of water vapor in the air can range from the barely detectable level in the midst of a deep winter cold spell to as much as 3.5 percent of every breath you take during a severe July heatwave. No matter what the season, the vast majority of the invisible water vapor in the atmosphere is contained in the lowest mile or two from its source at the surface.

At any one instant, the Earth’s atmosphere contains 3.75 million-billion gallons of water vapor – enough to cover the entire surface of the planet with 1 inch of rain if condensed. This amount is recycled, through evaporation powered by the Sun, 40 times each year in what is known as the hydrologic cycle.

In each of these 40 cycles, enough energy is expended to power the U.S. — the largest consumer of energy in the world — for 3,441 years! A truly astounding amount of energy.