Category Archives: Meteorology

Is the weather nicer on Memorial Day or Labor Day?

Memorial Day traditionally marks the beginning of the summer, while Labor Day marks the end.

People are bound to have their own recollections and opinions about which weekend more reliably delivers agreeable weather here in southern Wisconsin, and those opinions can be colored by many non-meteorological influences. Continue reading

Category: Meteorology, Seasons

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Did someone predict the recent Wisconsin tornado?

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

Category: Meteorology, Severe Weather

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Is the California drought over?

Drought in the United States has been assessed by a number of different measures over the last several decades. One of the older such measures is the Palmer Drought Index introduced in 1965. The Palmer Index is based on a … Continue reading

Category: Climate, Meteorology

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Why is the grass wet in the morning, when it didn’t rain?

Recent spring mornings have produced wet lawns. To explain this, we start with the fact that air contains water in the gas phase, called water vapor. Dew is made of liquid water that has condensed from some of the water vapor in the air.

Dew occurs when objects cool. A common example of dew formation is when drops of liquid form on the glass of an ice-cold drink. Dew forms when the object, such as the glass, cools down to the dew point temperature. Continue reading

Category: Meteorology, Phenomena

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What are the plant hardy zones and how do they relate to climate?

If you are involved with gardening, you probably are aware of the hardy zones listed on seed packets.

Southern Wisconsin is largely in zones 5a and 4b, while northern Wisconsin lies in zones 3a to 4a. Continue reading

Category: Climate, Meteorology, Seasons

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