Category Archives: Severe Weather
July was the month of revolution in both America and France in the late 18th century as we declared independence from Britain on July 4, 1776, and the French Revolution began with the assault on the Bastille in Paris on July 14, 1789. It is interesting to examine the extent to which weather may have influenced the passions that led to these seismic events.
The author of our Declaration, Thomas Jefferson, was such an avid weather observer that he brought his instruments with him from Monticello to Philadelphia that summer. He recorded a mild day on July 4 with a high temperature of 76 degrees. Phineas Pemberton, a prominent citizen, independently recorded the same high temperature – nearly 10 degrees Fahrenheit below normal. Pemberton also noted a wind shift from northerly to southwesterly with a falling pressure as often accompanies passage of a surface high-pressure system. Thus, the great revolutionary act in America was birthed in benevolent weather conditions. Continue reading
A derecho (pronounced deh-RAY-cho, a Spanish word meaning “straight ahead”) is an hours-long windstorm associated with a line of severe thunderstorms.
It is a result of straight-line winds, not the rotary winds of a tornado — hence its name. Derechos in the United States are most common in the late spring and summer (May through August). Continue reading
We cannot yet forecast tornado occurrence with any accuracy. One problem is the small size of a tornado, which is a narrow column of strong winds that rotate around a center of low pressure.
Over the last 60 years, forecasts of the development of large-scale low-pressure systems, which often organize the ingredients needed to form a tornado, have steadily improved. Because of these advances, meteorologists are better able to predict those conditions a few days in advance, enabling forecasters to identify counties where there is a threat of severe weather sometimes as many as three days in advance. Two days in advance of the recent EF-2 tornado that hit southeastern Polk County, the National Weather Service’s Storm Prediction Center’s convective outlook issued a slight-risk for the area. Continue reading
Wisconsin has had tornadoes in every month of the year except February.
We can have tornadoes almost anytime, although the chances of having one in winter are pretty small. Continue reading
In this country, Opening Day of the Major League Baseball season is more likely to be considered the start of spring than the vernal equinox that precedes it by two weeks each year.
However, as committed baseball fans surely know, the start of the season does not mandate the start of the warm season. In fact, though no definitive record of the total number of Major League games postponed by snow exists, quite a number of opening weeks have experienced widespread disruption as a result of early season snow. Most recently, opening weeks in 2007 and 2013 were plagued by numerous cancellations across both leagues. Continue reading