Category Archives: Climate

What kind of winter are we expecting?

Seasonal climate forecasts rely heavily on established relationships between climate and key climate forcing mechanisms, such as El Niño.

On seasonal time scales, the influence on the atmosphere of ocean temperature anomalies such as El Niño or La Niña is probably the single most crucial forecast component. This is especially true for forecasts of Wisconsin winters. Continue reading

Category: Climate, Meteorology, Seasons

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Did we have an Indian summer this year?

We are not sure of the origin of this expression, but it has been used for over 200 years in reference to a weather phenomenon that occurs in the fall, usually in October for our state. It occurs when the autumn weather is characterized as sunny and warm.

Indian summer can occur only after the first frost but before the first snowfall. It occurs after the leaves have turned color and includes dry weather conditions with maximum temperatures greater than 65 degrees and minimum temperatures greater than 33 degrees. Continue reading

Category: Climate, Seasons

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Is human activity to blame for climate change?

A recent debate between candidates for Congress in the Wisconsin’s 1st District — U.S. Rep. Paul Ryan, R-Janesville, and Democratic challenger Rob Zerban — included questions about the role of human beings in producing discernible changes in the climate over the last 150 years.

Unfortunately, this question, which is a matter of evidence, analysis and conclusion as all scientific questions are, has become a source of partisan political divide. Continue reading

Category: Climate

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What is the status of the ozone hole?

Ozone occurs about 18 miles above the surface. Ozone is both caused by and provides protection from damaging ultraviolet energy emitted by the sun. The development of an atmospheric “ozone layer” allowed life to move out of the oceans and onto land.

The ozone hole occurs high over the continent of Antarctica. It is not actually a hole, but rather the appearance of very low values of ozone in the stratosphere. Typically, the Antarctic ozone hole has its largest area in early September and lowest values in late September to early October. Continue reading

Category: Climate, Meteorology

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Do September temperatures foretell the nature of the winter?

After the recent abnormally cold period, which has left us 3.2 degrees colder than normal thus far in September, a lot of people have been wondering if September temperatures can be a harbinger of what is to come in the winter.

Everyone recalls last winter as a persistently cold season during which we experienced a four-month period (December 1 – March 31) with an average temperature that was 7.44 degrees below normal. Interestingly, last September was 2.7 degrees above normal and last October was 1.0 degrees above normal. Continue reading

Category: Climate, Meteorology, Seasons

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