The L3MTO is an extension of the national 3-month temperature outlook that NOAA's Climate Prediction Center (CPC) issues on the third Thursday of each month (http://www.cpc.ncep.noaa.gov/products/predictions/90day/ ), to a specific site. The L3MTO features the same information as the national 3-month temperature outlook, meaning the outlooks are provided for 3 categories (below, near, and above normal), and for the probability of exceedance. The difference is the L3MTO extracts more spatial detail, includes multiple presentation formats and supportive text for easier interpretation.
Forecast performance evaluation is essential to 1) guide the ongoing improvement in forecasting procedures, and 2) to guide users in assessing the potential usability of this product. To accomplish the first purpose, an extensive study was conducted on the overall L3MTO performance that included analysis using Continuous Ranked Probability Skill Scores (CRPSS), modified Heidke Skill Scores, and reliability diagrams. To accomplish the second purpose a forecast evaluation tool (http://fet.hwr.arizona.edu/ForecastEvaluationTool/), developed at the University of Arizona, is available via the L3MTO webpage. This user defined forecast evaluation tool provides multiple verification statistics for both national and local 3-month temperature outlooks. The analysis is available for user defined selection of any combination of 3-month periods and/or years during 1994 to the present. Overall, the study identified locations and 3-month periods with satisfactory forecast performance, and their spatial and temporal variability.