1. Medium Range Forecast - Global System Out To 14 Days Yuejian Zhu Ensemble Team Leader EMC/NCEP/NWS/NOAA Presents for NWP Forecast Training Class March 30, 2015, Fuzhou, Fujian, China

2. Medium Range Forecast - Global system out to 16 days Forecast objects –Mainly day 3-7 Weather pattern, front system, storm, cyclone tracks and etc… Variables: Temperature, precipitation and etc… –Week 2 Anomaly forecast, weather pattern transition, blockage and etc… 500hPa height, temperature (cold/warm), precipitation (dry/wet) Forecast Skills –Useful forecast for weather – 60% anomaly correlation –Useful skill for extended range – 50% anomaly correlation –Ensemble mean forecast skill – higher than deterministic forecast –Probabilistic forecast skill Forecast confidences –Evaluation/verification –Uncertainty levels –Confidence – good/bad example Forecast products –Deterministic – ensemble mean –Uncertainty forecast – ensemble spread, probabilistic forecast above/below thresholds Forecast examples –Deterministic or probabilistic? –Winter storm 2008 –Specific request project – Hanson Dam –Hurricane Sandy 2012

3. Case of weekend storm (2/8-9/2013)

4. http://www.emc.ncep.noaa.gov/gmb/yluo/CCPA.html ~20mm/day

5. 5 http://www.meteo.gc.ca/ensemble/naefs/index_e.html CMC’s week-2 NAEFS anomaly forecast

6. Medium Range Forecast - Global system out to 16 days Forecast objects –Mainly day 3-7 Weather pattern, front system, storm, cyclone tracks and etc… Variables: Temperature, precipitation and etc… –Week 2 Anomaly forecast, weather pattern transition, blockage and etc… 500hPa height, temperature (cold/warm), precipitation (dry/wet) Forecast Skills –Useful forecast for weather – 60% anomaly correlation –Useful skill for extended range – 50% anomaly correlation –Ensemble mean forecast skill – higher than deterministic forecast –Probabilistic forecast skill Forecast confidences –Evaluation/verification –Uncertainty levels –Confidence – good/bad example Forecast products –Deterministic – ensemble mean –Uncertainty forecast – ensemble spread, probabilistic forecast above/below thresholds Forecast examples –Deterministic or probabilistic? –Winter storm 2008 –Specific request project – Hanson Dam –Hurricane Sandy 2012

7. NH Anomaly Correlation for 500hPa Height Period: January 1st – December 31st 2014 GFS – 7.85d GEFS – 8.92d NAEFS – 9.26d Forecast day(s)

8. NH 500hPa height anomaly correlation (NCEP ensembles) Forecast Day(s)

10. RMS Error and Spread 5 days forecast 10 days forecast Courtesy of Dr. Yan Luo

11. Continuous Ranked Probabilistic Skill Scores 5 days forecast 10 days forecast Courtesy of Dr. Yan Luo

12. NAEFS Ensembles (left), Manual (right) & Auto (bottom) 8-14 day Precipitation (4/1/2010 –3/31/2011) Courtesy of Dr. Dan Collins Heidke Skill Score

13. 6-10 day Precipitation CPC Heidke Skill Score April 1, 2010 –March 31, 2011 All AreasWest/HighPlainsSouthMidwest/Northeast Manual13.810.317.514.8 Auto15.417.914.513.9 CDC20.325.219.315.3 NAEFS24.030.723.116.7 8-14 day Precipitation CPC Heidke Skill Score April 1, 2010 –March 31, 2011 All AreasWest/HighPlainsSouthMidwest/Northeast Manual 7.3 5.7 8.6 8.2 Auto10.412.6 9.1 9.2 CDC12.215.313.5 7.1 NAEFS15.820.716.7 9.3 Courtesy of Dr. Dan Collins

14. Medium Range Forecast - Global system out to 16 days Forecast objects –Mainly day 3-7 Weather pattern, front system, storm, cyclone tracks and etc… Variables: Temperature, precipitation and etc… –Week 2 Anomaly forecast, weather pattern transition, blockage and etc… 500hPa height, temperature (cold/warm), precipitation (dry/wet) Forecast Skills –Useful forecast for weather – 60% anomaly correlation –Useful skill for extended range – 50% anomaly correlation –Ensemble mean forecast skill – higher than deterministic forecast –Probabilistic forecast skill Forecast confidences –Evaluation/verification –Uncertainty levels –Confidence – good/bad example Forecast products –Deterministic – ensemble mean –Uncertainty forecast – ensemble spread, probabilistic forecast above/below thresholds Forecast examples –Deterministic or probabilistic? –Winter storm 2008 –Specific request project – Hanson Dam –Hurricane Sandy 2012

15. RMS Error for Northern Hemisphere (20-80N) 500hPa Height 13.72 10.91 62.50 49.97 50.06 (day-4) 1-d improvement (25% reduced error) for 10 years 62.46 (day-6)

16. TWO MAIN ATTRIBUTES OF FORECASTS RELIABILITY – Lack of systematic error (No conditional bias) Consider cases with same forecast Construct pdf of corresponding observtns If fcst identical to pdf of observations => PERFECT RELIABILITY Reliability CAN BE statistically corrected (assuming stationary processes) Climate forecasts are perfectly reliable – RELIABILITY IN ITSELF HAS NO FCST VALUE RESOLUTION – Different forecasts precede different observed events Consider different classes of fcst events If all observed classes are preceded by distinctly different forecasts => PERFECT RESOLUTION Resolution CANNOT BE statistically corrected INTRINSIC VALUE OF FCST SYSTEM

17. Good forecast ??? – you may like it

18. Bad forecast??? – give you a trouble?

19. Medium Range Forecast - Global system out to 16 days Forecast objects –Mainly day 3-7 Weather pattern, front system, storm, cyclone tracks and etc… Variables: Temperature, precipitation and etc… –Week 2 Anomaly forecast, weather pattern transition, blockage and etc… 500hPa height, temperature (cold/warm), precipitation (dry/wet) Forecast Skills –Useful forecast for weather – 60% anomaly correlation –Useful skill for extended range – 50% anomaly correlation –Ensemble mean forecast skill – higher than deterministic forecast –Probabilistic forecast skill Forecast confidences –Evaluation/verification –Uncertainty levels –Confidence – good/bad example Forecast products –Deterministic – ensemble mean –Uncertainty forecast – ensemble spread, probabilistic forecast above/below thresholds Forecast examples –Deterministic or probabilistic? –Winter storm 2008 –Specific request project – Hanson Dam –Hurricane Sandy 2012

20. Need one slide for median-range forecast Day 3-7 forecast Surface pressure Deterministic

21. NAEFS 500hPa height mean/spread and mean vorticity

22. Medium Range Forecast - Global system out to 16 days Forecast objects –Mainly day 3-7 Weather pattern, front system, storm, cyclone tracks and etc… Variables: Temperature, precipitation and etc… –Week 2 Anomaly forecast, weather pattern transition, blockage and etc… 500hPa height, temperature (cold/warm), precipitation (dry/wet) Forecast Skills –Useful forecast for weather – 60% anomaly correlation –Useful skill for extended range – 50% anomaly correlation –Ensemble mean forecast skill – higher than deterministic forecast –Probabilistic forecast skill Forecast confidences –Evaluation/verification –Uncertainty levels –Confidence – good/bad example Forecast products –Deterministic – ensemble mean –Uncertainty forecast – ensemble spread, probabilistic forecast above/below thresholds Forecast examples –Deterministic or probabilistic? –Winter storm 2008 –Specific request project – Hanson Dam –Hurricane Sandy 2012

23. Case 1: Deterministic/Probabilistic Forecast QPF.vs. PQPF Northern California State Christmas-New Year flooding. Winter storm last more than 10 days. Total precipitation amount exceeding 660mm over the huge area. The homes of 100,000 residents who has been evacuated. Some stranded residents has to be rescued by helicopter. Caused a lot of damages include road, bridge and resident houses. Photo from Washington Post (1996)

24. 24 hours observation GFS ENS

25. High predictable heavy precipitation event February 12-13 1997 (Southern Louisiana flooding) Location and intensity GFS ENS GFS made a very good forecast, But Ensemble made a excellent forecast.

26. Case 2: Southern China Winter Storm 2008 Period of 01/15-01/30/2008 Location: South of China – very large area Continuous precipitation all over the area –Large area snowfall –Large area freezing rain, ice pellets and mixing rain Typical extreme event –Less than 1% chance in climate Timing –Chinese Lunar New Year preparing (transportation?) Prediction/protection –Very limited??? –Protection – cost/loss problem – economic values Loss –Lives –Powers –Closed highways and other transportations Question left for us: do we need to pay attention to study this case?

29. What is about NCEP global ensemble forecasts? 500hPa height pattern RMOP

30. Unstable pattern Since mid of January Stable weather pattern Starting from Jan. 23rd Key: The trough didn’t move that much for a week

32. NCEP GEFS real time Probabilistic Precipitation Type Forecast (10-day)

33. NCEP GEFS real time Probabilistic Precipitation Type Forecast (5-day)

34. NCEP GEFS real time Probabilistic Precipitation Type Forecast (1-day)

35. Case 3: Flood Risk Management BAMS article 2012: NOAA’S RAPID RESPONSE TO THE HOWARD A. HANSON DAM FLOOD RISK MANAGEMENT CRISIS NOAA operations and research personnel joined forces to better predict a possible flood and help calm public fears regarding reduced flood protection from a western Washington dam.

36. Results of sensitivity tests translating hypothetical heavy rainfall on the Green River over 24 h into HHD inflow. The runs were conducted by the NWRFC and used varying antecedent conditions (soil moisture and snow pack). The levels of risk were assigned based on inflow thresholds defined by the USACE. (Refer to BAMS)

37. ECMWF Ensemble Mean NCEP GFS Ensemble MeanHFIP GFS Ensemble Mean Case 4: Hurricane Sandy Forecast

38. Canadian Ensemble MeanNavy Ensemble Mean UKMET Ensemble Mean

40. 25% 50% 75%50% Climate Forecast 85% 95% 99% Schematics diagram for anomaly forecast (PDF) GEFS Based Anomaly Forecast

41. 25% 50% 75% 50% Climate Forecast 85% 95% 98% Schematics diagram for anomaly forecast (CDF) Ensemble member #5 (ranked) Ensemble member #11 (ranked) Ensemble member #16 (ranked) 68.2% 95.4% 99.6%

48. 8-day fcst6-day fcst 5-day fcst4-day fcst