NOAA Product Highlight: Precipitation

As was felt recently at the South Carolina Botanical Garden, extreme precipitation and flooding can be exceptionally devastating. Excess rains can wash away trails, compromise bridges, and harm many varieties of plants in public gardens. Sometimes no amount of planning or preparedness can help in flooding situations, but NOAA provides a wide variety of precipitation information to enable government and institution leaders to make the best decisions and the most preparation possible.

NOAA’s National Climatic Data Center (NCDC) has many climate precipitation monitoring products available, including National Precipitation Maps. These regional, divisional, and statewide color-coded maps represent the rank of a particular month and season as compared to the historical record based on one-month, three-month, six-month, twelve-month, and year-to-date time spans. Each region, division, or state is given one of seven categories: record driest, much below normal, below normal, near normal, above normal, much above normal, and record wettest.

NCDC produces Weekly Divisional Products to augment the National Precipitation Maps and additional standard monthly products. These weekly divisional products include temperature, temperature departure from average, precipitation, precipitation departure from average, and long- and short-term drought maps. The most recent maps are added within three days of the end of each week.

NCDC also provides similar numerical statistics through their Climatological Rankings application. This application allows users to look up monthly U.S., statewide, division, and regional temperature, precipitation, degree day, and drought rankings for a variety of time periods. For example, the precipitation rankings include the amount of precipitation recorded in the area during the selected time frame, the 20th century average, the departure from normal, where that time ranks as either wettest or driest since January 1895, when the record wettest and driest times happened, and how long it has been since a wetter or drier time occurred.

The U.S. Climate at a Glance Tool, available from NCDC, is another way to obtain near-real-time analyses of monthly data across the contiguous United States. This tool allows users to view how certain parameters, such as precipitation, have changed in a particular place across the country since 1895. The data can be viewed with either an interactive time series graph or an interactive map. As with the previously mentioned applications and tools, Climate at a Glance also allows selection of a variety of regions and periods, but this tool also allows users to view trends within the data to study climate variability and change.

An assortment of precipitation products and analyses are also available from NOAA’s National Weather Service (NWS) through their Advanced Hydrologic Prediction Service. NWS provides observed precipitation, normal precipitation, and derived precipitation products. The observed precipitation data is expressed as a 24-hour total for a specific location. The normal precipitation data is calculated as the 30-year average at a specific location and is expressed as the monthly normal for rainfall. The derived precipitation products, which include “departure from normal” and “percentage of normal” graphics, are generated using the normal and observed data. All of the NWS precipitation analysis pages are routinely updated six times per day, at approximately 10:00 a.m., 12:00 p.m., 2:00 p.m., 4:00 p.m., 6:00 p.m., and 8:00 p.m. Eastern Time.

All of these precipitation related data and products are just part of the suite of climate services NOAA provides to government, businesses, academia, and the public to support informed decision making.


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