1. Regional Verification of CPC’s Seasonal Outlooks Michael Halpert & Kenneth Pelman Climate Prediction Center

2. Seasonal Outlook Schedule/Leads Each month, near mid-month CPC prepares a set of 13 outlooks for 3-month “seasons” (any set of 3 adjacent months) for lead times ranging from ½ month, 1 ½ months, 2 ½ months, 3 ½ months, …, 12 ½ months. The outlook for each successive/prior lead time overlaps the prior/successive one by 2 months. This overlap makes for a smooth variation from one map to the next.

3. Outlook Categories and Probabilities  Seasonal outlooks are prepared for average temperature and total accumulated precipitation category  Three categories are used (terciles). These are BELOW-,NEAR- and ABOVE-normal (median), for temperature (precipitation).  Regions where the likelihoods of the three categories are the same (33.33…% each) are designated as “EC”, for equal chances.  In non-EC regions the labels on the contours give the total probability of the dominant category.

4. Verification Heidke Skill Score H=[ ( NC – CH)/(NT – CH) ] * 100 H=Heidke Skill Score NC = total number of correct forecasts by station NT = total number of forecasts made by station CH = number of correct forecasts, by chance In 3 class system, scores range from -50 to +100

5. Examples a. 99 stations, 50 correct forecasts H = [(50-33)/(99-33)] *100 = 25.8 b. 51 stations, 12 correct H = [(12-17)/(51-17)]*100 = -14.7 c. 45 stations, 35 correct H=[(35-15)/(45-15)*100 = 66.7 Verification

6. 0.5 Month Lead Skill

7. Data 9+ years of seasonal forecasts JFM 1995 – AMJ 2004 112 Total Forecasts Winter: NDJ – JFM (28) Spring: FMA – AMJ (30) Summer:MJJ – JAS (27) Fall:ASO – OND (27)

8. Temperature – All Seasons

9. Temperature – By Season Winter Spring Summer Fall

10. Temperature – By Category (All) Above Below

11. Temperature - Category DJF&MAM Winter/Above Winter/Below Spring/AboveSpring/Below

12. Temperature - Category JJA&SON Summer/Above Summer/Below Fall/AboveFall/Below

13. Temperature Summary (Official) Good skill from the Pacific NW, peaking in the SW and extending through the South. No skill in N. Plains, Great Lakes, NE Winter forecasts best, Fall poorest No skill in NE, always skill in SW All skill comes from above normal; negative skill everywhere for below

14. Forecast Tools 1.Optimal Climate Normal (OCN) 2.Canoncial Correlation Analysis (CCA) 3.Coupled Model (CMP) 4.Screened Multiple Linear Regression (SMLR)

15. Temperature – OCN/CCA All OCN CCA

16. Temperature – OCN/CCA By Category OCN/Above OCN/Below CCA/Above CCA/Below

17. Temperature – SMLR/CMP All SMLRCMP

18. Temperature – SMLR/CMP By Category SMLR/AboveSMLR/Below CMP/Above CMP/Below

19. Forecast Tools - DJF OCN CCA CMP SMT

20. Forecast Tools - MAM OCN CCA CMP SMT

21. Forecast Tools - JJA OCN CCA CMP SMT

22. Forecast Tools - SON OCN CCA CMP SMT

23. Precipitation – All Seasons

24. Precipitation – By Season Winter Spring Summer Fall

25. Precipitation – By Category (All) Above Below

26. Precipitation - Category DJF&MAM Winter/Above Winter/Below Spring/AboveSpring/Below

27. Precipitation - Category JJA&SON Summer/Above Summer/Below Fall/AboveFall/Below

28. Precipitation Summary (Official) Skill in West, South and NE (few cases) Skillful regions vary by season Skill in all seasons in NW, except Spring Skillful forecasts for both above and below in the SW and along Gulf Coast, FL Skill for winter/spring forecasts for below in South, only along Gulf Coast for above

29. Precipitation – OCN/CCA All OCN CCA

30. Precipitation – OCN/CCA By Category OCN/Above OCN/Below CCA/Above CCA/Below

31. Precipitation – SMLR/CMP All SMLRCMP

32. Precipitation – SMLR/CMP By Category CMP/AboveCMP/Below SMLR/Above SMLR/Below

33. Forecast Tools - DJF OCN CCA CMP SMT

34. Forecast Tools - MAM OCN CCA CMP SMT

35. Forecast Tools - JJA OCN CCA CMP SMT

36. Forecast Tools - SON OCN CCA CMP SMT

37. DJF 2004-2005 Outlook