Scattered severe thunderstorms are forecast across central and eastern North Dakota, as well as far northwest Minnesota Saturday (Slight Risk level 2 of 5). Damaging wind gusts are the primary threat. Elevated to critical fire weather conditions will persist through the weekend across the Western U.S. Isolated dry thunderstorms could lead to new fire starts over portions of the northern Rockies. Read More >
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Every ten years the National Center for Environmental Information (NCEI - formerly the National Climatic Data Center) calculates a new set of U.S. 30-year normals. So just what are "Normals"? In the strictest sense, a "normal" of a particular variable (e.g., temperature) is defined as the 30-year average. For example, the minimum temperature normal in January for a station in Tampa, Florida, would be computed by taking the average of the 30 January values of monthly averaged minimum temperatures from 1991 to 2020. Each of the 30 monthly values was in turn derived from averaging the daily observations of minimum temperature for the station. In practice, however, much more goes into NCEI's Climate Normals product than simple 30-year averages. Procedures are put in place to deal with missing and suspect data values. In addition, Climate Normals include quantities other than averages such as degree days, probabilities, standard deviations, etc. Climate Normals are a large suite of data products that provide users with many tools to understand typical climate conditions for thousands of locations across the United States. Key Takeaways:
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Conventional 30-Year Normals and New Supplemental 15-Year Normals: |
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What do the New Normals Say? |
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All images on this page can be magnified by clicking, and resized back to original size with a second click. |
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Taking a look at how the temperatures and precipitation normals have changed compared to the 20th-Century (1901-2000) we see in the images below that there has been some variability over the decades, but most recently we see warming across most of the continental U.S. with wetter conditions over the central and northeast U.S. and drying in the southwest states. |
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What’s included in the Normals? |
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