Seasonal forecasts predict whether temperatures and precipitation in an area will be above average or below average for an upcoming season. This tool tells users how accurate these predictions have been in the past.
If understood and used properly, long-range forecasts can greatly aid in the management of water, fires, cattle, agriculture, energy and more.
"There is so much misinterpretation concerning climate forecasts in general," said Holly Hartmann, a University of Arizona hydrologist, and lead author of a paper that is the cover story in the May issue of the Bulletin of the American Meteorological Society. "Part of our tool tries to make sure that forecasts are easy to interpret and that people can reliably interpret them."
When millions of dollars and lives are at stake, resource managers have been tentative about taking advantage of sophisticated climate forecasts available on the Web. By explaining and evaluating these forecasts, the new tool helps decision makers utilize them regardless of their training. "One of the major reasons why natural resource managers don't use climate forecasts is because they don't know how good they are," said Tom Pagano, a University of Arizona researcher, and co-author of the paper.
Seasonal forecasts are made through the use of data from satellites, computer models, and ocean buoys. Scientists predict the climate of future seasons based on interactions between atmospheric pressures and slowly varying ocean temperatures. They then compare these assessments with historical weather patterns.
The tool allows users to customize evaluations to consider the lead-times, seasons and locations most relevant to each resource manager's specific needs.
For example, the high likelihood of a wet winter gives water reservoir managers in the southwest more confidence when they make decisions to let water out of a reservoir in the fall. A mistake can lead to water shortages, as well as millions of dollars spent pumping ground water.
Ranchers, on the other hand, use seasonal forecasts to make predictions concerning winter and summer climates that effect grass growth. By having an idea of the probability of unfavorable conditions, they can stock up on hay ahead of time.
Also, wildfire managers may use seasonal forecasts of temperatures and rainfall early in the year to budget their resources for the rest of the year, make decisions about fire risks, and figure out when might be a good time to conduct prescribed burns, and rehabilitate previously burned areas.
The on-line tool is currently set up to assess the seasonal outlooks regularly issued by the National Weather Service (NWS) Climate Prediction Center (CPC), which serve as the government's official forecasts.
"Since seasonal forecasts aren't as consistently reliable as short term weather forecasts, it's important that we communicate their performance characteristics in a way that users can understand and exploit the forecast," said Robert Livezey, chief of the NWS Office of Climate, Weather, and Water Services, and a former senior scientist at the CPC. "This work makes substantial progress in this regard for specific users."
Funding for the project was provided through grants from NASA's Earth Observing System, and the National Oceanic and Atmospheric Administration.
Currently in the latter stages of development, the site will be made public by late summer through the University of Arizona's Hydrological Data and Information System (HyDIS) website: http://hydis.hwr.arizona.edu/.
Potential users interested in final testing of the site can contact Holly Hartmann at hollyh@hwr.arizona.edu.
For more information, please see:
http://www.gsfc.nasa.gov/topstory/20020523tool.html
Journal
Bulletin of the American Meteorological Society