Author Archives: WeatherGuys Editor

Does fall give any hints about the intensity of the coming winter?

Each winter we keep track of the areal extent of air colder than 23 degrees Fahrenheit at the 850 mb pressure level (about 1 mile above sea-level) around the entire Northern Hemisphere. This measure allows us to characterize the intensity of the winter season with respect to the lower tropospheric temperature.

Over the past 75 seasons there has been a systematic decrease in the December-January-February, or DJF, average areal extent of about 4.6%, and this is an unequivocal sign of global warming, measured in the winter season. Continue reading

Category: Climate, Seasons

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How can there be frost on the ground when my thermometer reads 36 degrees?

This set of circumstances does not mean that her thermometer is faulty and in need of replacement. Instead, it reflects a nearly daily reality that goes undetected for most of the year until the cold season. It turns out that the air does not radiate heat away nearly as well as the solid ground beneath it. As a consequence of this difference, given 13 hours of nighttime with clear skies, the ground radiates a lot more energy away (and cools rapidly) while the air above struggles to cool as efficiently. Over those many hours, this difference results in a big difference between the ground temperature and the air temperature even as little as 5 or 6 feet above the ground. Continue reading

Category: Meteorology, Phenomena

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What is the National Climate Assessment?

The U.S. National Climate Assessment is mandated by the Global Change Research Act of 1990. The assessment is conducted about every four years and is an authoritative scientific analysis of climate change risks, impacts and responses in the U.S.

The nation this month completed the Fifth National Climate Assessment, or NCA5. The National Oceanic and Atmospheric Administration is the administrative agency for NCA5 and certifies that the report meets Information Quality Act and Evidence Act standards. The assessment is an extensive process that includes internal and external review from federal agencies, the general public and external peer review by a panel of experts. Continue reading

Category: Climate, History, Seasons, Severe Weather

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What is a gale wind?

A gale is a strong, sustained wind impacting maritime weather.

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Category: Meteorology, Severe Weather

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What role did Wisconsin play in establishing the National Weather Service?

Wednesday was the 153rd anniversary of the first day of operation of what has become the National Weather Service. On Nov. 1, 1870, the first organized set of observations around the country were taken under the auspices of the Army Signal Service.

On Feb. 9 of that same year, President Ulysses S. Grant, fresh from his own experiences during the Civil War, enthusiastically signed the service into existence. Its purpose was “to provide for taking meteorological observations at the military stations in the interior of the continent and at other points in the States and Territories … and for giving notice on the northern (Great) Lakes and on the seacoast by magnetic telegraph and marine signals, of the approach and force of storms.” Continue reading

Category: Uncategorized

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