Figure
12. Temperature Verification (November 2009–April 2010)
Source:
NOAA-Climate Prediction Center (CPC)
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Comparisons of observed temperatures for November–January to forecasts issued in October for the one-month lead time covering the same period suggest that forecasts are most reliable in southeast and northwest Arizona and southern New Mexico (Figure 12a). Forecast skill—a measure of the accuracy of the forecast—for northern New Mexico has not been much better than using equal chances as a forecast. Forecast skill for the two-month lead times (forecasts issued in October for December–February) suggest that for most of Arizona and New Mexico, forecasts have been slightly more accurate than the equal chances forecast (Figure 12b). The most accurate forecasts for this time period have again been for northwestern Arizona. The three-month lead time forecast has been more accurate than equal chances in all regions of Arizona and New Mexico (Figure 12c). Regions with bluish hues suggest that the NOAA–Climate Predictions Center (NOAA–CPC) forecasts have historically been more accurate than equal chances. However, caution is advised to users of the NOAA–CPC seasonal outlooks for regions where the verification maps display reddish hues.
Notes: These maps evaluate the historical performance of the one- to four-month long-lead forecasts made by NOAA’s Climate Prediction Center (CPC). The maps convey the historical accuracy of the CPC forecasts in relation to the reference forecast, which assigns a 33 percent chance to the three CPC categories, “above,” “below,” and “neutral.” These categories indicate whether conditions are predicted to be similar to the warmest, coolest, or normal temperatures for 1971 to 2000. The maps are generated from the Forecast Evaluation Tool, which was developed by The University of Arizona in partnership with NOAA, NASA, NSF, and the University of California-Irvine
The maps display the Ranked Probability Skill Score (RPSS). The more the forecasts and actual weather match, the bluer the color. A bluish or reddish RPSS indicates the forecast is more accurate or less accurate, respectively, than assigning a 33 percent chance to each of the three CPC categories.
The RPSS is calculated by comparing all the forecasts made since December 1994 for particular seasons and specified lead times to the actual weather of the season.
More
Information:
For more information on the Forecast Evaluation Tool, visit:
http://fet.hwr.arizona.edu/ForecastEvaluationTool/
For a CLIMAS publication that explains how to use the Forecast Evaluation Tool, visit:
http://www.climas.arizona.edu/forecasts/articles/FET_Nov2005.pdf