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United States Department of Agriculture

Agricultural Research Service

Title: Cpc's Seasonal Precipitation Forecasts Versus Climatology: How Different Are They?

Authors
item Schneider, Jeanne
item Garbrecht, Jurgen

Submitted to: Annual Hydrology Days Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: April 2, 2001
Publication Date: April 2, 2001

Interpretive Summary: Interpretive Summary: NOAA produces seasonal climate forecasts for total precipitation, average temperature, and other climatic variables. The use of these seasonal forecasts for planning and decision making in agricultural and natural resource management requires evaluation of forecast value and utility. Visual surveys of archived precipitation forecasts had revealed that forecasts were frequently identical, or very close, to historically average conditions. Forecasts for near-normal conditions would be of limited value in many agricultural and natural resource applications, since best management practices are already tuned to average conditions. A preliminary study was conducted to summarize the size and frequency of the difference between the precipitation forecasts and average conditions. For the three forecast divisions examined, forecasts were more than 10% different from average conditions an average 12% of the time. If these results are representative of the U.S., the usefulness of the forecasts will be limited for certain applications. Further analysis is underway, and the results will help define which regions and agribusiness segments might best benefit from these precipitation forecasts.

Technical Abstract: Technical Abstract: The Climate Prediction Center, a branch of the National Oceanic and Atmospheric Administration, produces climate forecasts that predict average temperature and total precipitation over three- month periods out to a year in advance. A visual inspection of past precipitation forecasts versus 30-year average precipitation values, called climatology, suggests that the forecasts rarely differ much in magnitude from corresponding climatology. Based on the available archived forecasts from 1995 through 1999, an initial evaluation of the frequency and degree of departure of precipitation forecasts from climatology was performed for three forecast divisions. For these three regions combined, forecast departures were larger than 10% of climatology in only 12% of the forecasts. This may limit the usefulness of these forecasts for certain applications. Further analysis on this subject is underway, part of a comprehensive, user oriented evaluation of the value of CPC's seasonal precipitation forecasts for applications in agriculture and natural resource management.

Last Modified: 12/17/2014
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