REVIEW OF RECOMMENDATIONS FROM THE 3 RD ENSEMBLE USER WORKSHOP (OCT. 2006)

1. Zoltan Toth Environmental Modeling Center NOAA/NWS/NCEP Acknowledgements: Louis Uccellini, Steve Lord & Ensemble Team Paul Schultz, DJ Seo, Tom Hamill, Steve Mullen, Julie Demargne http://wwwt.emc.ncep.noaa.gov/gmb/ens/index.html REVIEW OF RECOMMENDATIONS FROM THE 3RD ENSEMBLE USER WORKSHOP (OCT. 2006)

2. MAJOR RECOMMENDATIONS - 1 FOLLOW NRC REPORT RECOMMENDATIONS All major recommendations embraced • Develop roadmap for assessing & communicating forecast uncertainty • Based on science, technology, workforce considerations • Consistent with NOAA’s mission, NWS plans, embraced by “Enterprise” • Define end goal, 5-10 years horizon • Adopt ensemble-based forecast process • Maximize forecast skill • Unify scientific, software, and technological infrastructure across NOAA • Weather, water, climate applications • Suggested in Mar 2007 to develop roadmap by Sept. 2007

3. MAJOR RECOMMENDATIONS - 2 • Develop roadmap for assessing & communicating forecast uncertainty • Revise operational requirements to make them probabilistic • Make probabilistic format the primary requirement • For each forecast application: • Replace single value/categorical format with probabilistic format as primary requirement • Revise/supplement corresponding performance measures (GPRA) • Essential for orderly transition from traditional to new forecast process • NWS is requirement-driven organization • Without clear new requirements, process is doomed • Phased implementation schedule in consultation with responsible offices • Allows orderly transition to new requirements • Suggested in Mar 2007 to prepare plan by March 2008

4. MAJOR RECOMMENDATIONS - 3 • Develop roadmap for assessing & communicating forecast uncertainty (.5 yr) • Revise operational requirements to make them probabilistic (1 year) • Design, develop, and gradually implement new forecast process • Focus on missing scientific, technological, and human components • Identify self-contained components with • Clear requirements and interfaces between components • Define basic capabilities achievable in 2-3 years • Limited but consistent with and leading to end goal • Full capabilities in 5-10 years • Interface with NOAA THORPEX program • Research/development to improve skill & utility of probabilistic forecasts • Leverage related major NOAA, national, and international efforts • Integrate with NWS, NOAA, national activities • NOAA-wide regional service plans • NUOPC planning/development • Provide long-term funding support through PPBES • Overlap with W&W High Impact Event Theme Team • Form development teams for specific tasks/components following workshp • Identify potential contributors within & outside of NWS & NOAA

5. SPECIFIC RECOMMENDATIONS – 1-3 • Continue development of expanded forecast process • Focus on adaptive methods applicable for high impact events • Collection & use of observations (targeted observations) • Data assimilation (case dependent background error estimation) • Numerical modeling (adaptive resolution & high impact modeling) • Ensemble forecasting (case dependent variations in membership & composition) • Decision support systems (flexible user actions depending on forecast probabilities) • Bias correction & downscaling methods for ensembles • Estimate/correct lead-time dependent bias in ensemble forecasts (on model grid) • Generate fine resolution (NDFD grid) uncertainty/ensemble data • Establish connection between (bias corrected) coarse model vs. fine user grids • Use reanalysis & hind-casts with operational systems as needed • Define summary ensemble information to be used to (ST) • Collapse vast amount of ensemble data for inclusion in expanded NDFD/NDGD • E.g., 10, 50, and 90 percentile of forecast distribution (in place of single value) • Manually inspect/modify summary ensemble information ST – Short Term (2-3 yrs); LT – Long Term (5-10 yrs)

6. SPECIFIC RECOMMENDATIONS – 4-6 • Contribute to establishment of NOAA-wide environmental data depository • Expand NDFD/NDGD database to include forecast uncertainty (ST) • Develop capability to hold all ensemble trajectories (LT) • All members, variables, lead times • Develop ensemble interrogation, modification, & product generation tools to • Derive summary information from ensemble (ST) • Manually modify summary ensemble info (ST) • Derive additional statistics from summary info (product generation, ST) • Automatically modify ensemble trajectories based on modified summary info (LT) • Derive any info from full ensemble data (product generation, LT) • Develop telecommunication facilities to access data • Summary info & limited derived products (ST) • All ensemble forecasts & derived products (LT) ST – Short Term (2-3 yrs); LT – Long Term (5-10 yrs)

7. SPECIFIC RECOMMENDATIONS – 7-9 • Develop unified NWS/NOAA probabilistic verification package to (ST) • Assess statistical reliability and resolution for • Computing official performance measures • Evaluating value added along forecast chain • Assessing value in newly developed vs. operational techniques • Develop & implement comprehensive training to • Prepare all participants for their new roles in expanded forecast process, incl. • Statistical background • Ensemble methods • Best forecast practices in assessing uncertainty • Applications of probabilistic & other uncertainty information • Develop outreach program on use & communication of uncertainty • In partnership with entire Weather, Water & Climate Enterprise • Determine best ways of communicating uncertainty • Compile sample of Decision Support Systems using uncertainty information • Establish close partnership with public sector users (e.g., emergency, water management) • User feedback on new activities • Explore how forecast process can be adapted according to user requirements ST – Short Term (2-3 yrs); LT – Long Term (5-10 yrs)

8. NEW DEVELOPMENTS SINCE WG RECOMMENDATIONS NOAA/NWS Forecast Uncertainty Team (NFUSE) formed Early 2007 Assess and discuss status, search for solutions AMS ACUF Team formed Enterprise planning activities NOAA/NWS Forecast Uncertainty program formed Outgrowth of NFUSE Oversight panel established Budget planning for out-years Uncertainty-related activities wide-spread, affect all forecasting What is next? Coordinated Work level plans Related activities

9. 2008 WORKSHOP CONTRIBUTIONS Agree on long term plan What we want in 5-10 yrs – desired end result/framework Not how we achieve goal Multiple avenues can be tested within single framework Agree on what we can achieve in next 2-3 years with expected resources Limited version of long term goal – interim result/framework Development of short term solution will contribute to long term plan Contribute to forming of Work Teams addressing well defined sub-problems Separate pieces that can be worked on independently Leads/principles provide overall coordination

10. DISCUSS / AGREE ON LONG TERM GOAL Capability to answer any question related to future weather, climate, water, including forecast uncertainty Considering state of related science, what do we need for that? Bias corrected, downscaled ensemble forecasts – Ultimate dataset Allows derivation of single/joint probabilities Information on spatial/temporal/cross-variable correlations Trajectories (scenarios) Work independent of particular product/service needs (all questions covered) Major technical requirements Storage for ensemble data 20-100 times more data compared to current “NDFD” Distribution of / access to ensemble data 20-100 fold increase in bandwidth Technical tools to display / manipulate ensemble data Special AWIPS-2 capabilities Forecasters trained to work with ensemble data 2-step approach warranted First implement limited capability Will provide large portion of total benefit with relatively small investment

11. DISCUSS / AGREE ON INTERMEDIATE GOAL Capability to provide uncertainty/probabilistic info on any weather element with some approximation Considering state of related science, what do we need for that? Summary info that allows the generation of single-variable cdf/pdf Bias corrected, downscaled Can be generated based on a single or ensemble NWP Allows derivation of single-variable probabilities Including information on spatial/temporal/cross-variable correlations Technical requirements Storage for summary info 3-fold increase in NDFD data Distribution of / access to ensemble data 3-fold increase in bandwidth Technical tools to display / manipulate ensemble data Subset of long term toolkit in AWIPS-2 Connect summary stats & cdf/pdf Forecasters trained to work with ensemble data With right choice of summary info, forecasters eased into new paradigm

12. PHASE 1 PLAN • Important element Definition of basic format for forecast uncertainty • Advantages of using a common format • Facilitates flow of info between three major elements in forecast process • Numerical guidance • Human forecasters • External users • Provides basis for collaboration among various groups • Inter-comparison of different approaches • Requirements • Can be easily interpreted by users • Intuitive meaning • Can be manipulated by forecasters • Related to current forecast modification practices • Can be easily communicated • Limited data volume • Can be stored in NDFD • Related to current forecast format • Additional formats can be easily derived • Based on standard statistical considerations • Choice of exact format not critical • As long as software available to generate alternate formats

13. CHOICE OF FORMAT FOR ASSESSING AND COMMUNICATING FORECAST UNCERTAINTY • Background on suggested type of format • Recommended by Predictability WG at WR/NWS SOO/DOH Workshop (Salt Lake City, May 2003) • Discussed and recommended by Predictability Workshop at Univ. Wisconsin (Madison, Mar 2004) • Studied in detail and adopted at UKMET Office (2006) • Suggested format • Beyond mid-point estimate (50%, or mode, or mean?), include • Two additional fields for each NDFD variable • 10 percentile value of forecast distribution • 90 percentile value of forecast distribution • Readiness • Numerical guidance • Can be generated based on ensemble data, using NAWIPS software • Forecasters • Can use same tools to manipulate 2 new fields as with most likely field • Users • UKMET research indicates this is intuitive

14. BACK

15. EXAMPLE FROM UK METOFFICE - TEMP Courtesy of Mark Roulston

16. EXAMPLE FROM UK METOFFICE - PRECIP Courtesy of Mark Roulston

17. QUESTIONS ABOUT SUGGESTED FORMAT • Does it make sense, reasonable format? • No need to worry (too much) • Just need a common format to connect three main areas • Alternative formats can/will be generated • What NDFD grids describe currently? • Most likely value (mode of pdf)? • Expected value (mean of pdf)? • 50% exceedence value (median of pdf)? • What mid-point parameter an expanded NDFD should have? • What do users need? • What is most intuitive to forecasters? • Would median (50 percentile) be best choice? Similar to 10, 90 percentile value • What threshold may work best for limits? • 10 & 90 - not too narrow, not too wide? • 5 & 95 percentile may be too extreme for forecasters? • 20 & 80 may not be inclusive enough? • What software needs to be developed to generate other formats? • Fit parametric distribution to 3 points • Roman Krzysztofowicz’ library of 40+ distributions • Any probability or its inverse can be derived for single variables • Basic probabilistic forecast data-base

18. TOOLS NEEDED FOR INTERMEDIATE STEP Modify summary statistics (forecasters’ role) Fit parametric distribution to modified summary statistics Adjust ensemble members to be consistent with official forecast For users who need trajectories Derive probabilities from fitted cdf/pdf Same statistical tools must be used across organization Ensemble generation, display, manipulation, product generation, etc Same tools can be used in final stage to manipulate ensemble distribution Summary statistics inspected & modified by forecasters Changes back-propagated to ensemble data set

19. WORK AREAS All topics need to be developed in coordination Plenary sessions for interactions Topics A & B are especially connected in each WG Same groups discussing both topics in 2 sessions Third WG session to focus on connections Working Group 1 Topic A Operational requirements Topic B Corporate outreach Working Group 2 Topic A Ensemble forecasting Topic B Statistical post-processing Working Group 3 Topic A Ensemble data depository / access Topic B Database interrogation / forecaster tools Working Group 4 Topic A Forecaster’s role Topic B Forecaster training

20. WORK AREAS Operational requirements General requirements first to “justify” effort Detailed requirements later as effort unfolds Corporate outreach Link with ACUF process Promote quantitative use of uncertainty information in Decision Support Systems Ensemble forecasting Centerpiece of uncertainty effort THORPEX NOAA, national, international research/development NAEFS, NUOPC, TIGGE, GIFS

21. WORK AREAS – CONT Statistical post-processing Problem Relate coarse resolution biased forecast to user relevant fine resolution information Break up problem to facilitate collaboration Bias correction of coarse resolution forecast grid wrt NWP analysis Cheap Sample of forecasts / hind-casts needed Downscaling Relate coarse resolution NWP and fine resolution observationally based analyses Perfect prog approach No need for hind-casts Creation of observationally based fine resolution analysis Estimate of truth Groups can collaborate on each topic Addressing all 3 problems in one swoop limits collaboration

22. NAEFS RESULTS • 8 days total gain in skill • Downscaling more important than bias correction • Less need for hindcasting? • Need for local observationally based analysis • Multicenter approach adds 1-2 days skill NCEP biascorrected-downscaled NCEP raw-downscaled NCEP raw NAEFS final

23. WORK AREAS – CONT 2 Ensemble data depository / access Create NOAA digital forecast database (linked with other NOAA data) Summary statistics in phase 1 All ensemble members in phase 2 Provide easy access to internal / external users NOMADS, etc? Link with multi-center ensembles NAEFS – NUOPC – GIFS Database interrogation / forecaster tools Derive information from summary stats / ensembles Modify summary stats Back-propagate modified info into ensemble Verify added value at each step of forecast process Need for unified verification capability across forecast process Common requirement across all WGs

24. WORK AREAS – CONT 3 Forecaster’s role Traditional role Generate forecast, or modify numerical guidance Changing environment Need to generate very large amount of forecast data Quality of automatic numerical guidance improves New role: Direct and quality control forecast process Identify high impact events Assign adaptively configurable observational, modeling, etc resources Interfere with automated process only during critical high impact events User outreach Interpret probabilistic forecast Forecaster training Prepare for new role related to ensemble / probabilistic forecasting Modification Interpretation Outreach

25. Surface Temperature MAE CONUS, Sept. 2007 00Z GMOSvs. 00Z NAEFS Surface Temperature MAE CONUS, Sept. 2007 12Z NDFD vs. 00Z MOS/GMOS/NAEFS RTMA Analysis METAR obs. 1221 sites GMOS forecast 0.5°C NAEFS products 0.5°C

26. Surface Temperature Pointwise Bias CONUS, Sept. 2007 00Z GMOSvs. 00Z NAEFS Surface Temperature Area Mean Bias CONUS, Sept. 2007 12Z NDFD vs. 00Z MOS/GMOS/NAEFS Area Mean Bias Pointwise Bias RTMA Analysis METAR obs. 1221 sites GMOS forecast 0.6°C 0.6°C NAEFS products

27. BACKGROUND

28. Example for using new mask

29. MDL GMOS & NAEFS Downscaled Forecast Mean Absolute Error w.r.t. RTMA Average For Sept. 2007 12-h GMOS Forecast 12-h NAEFS Forecast For CONUS: NAEFS(1.01) : GMOS(1.59) 36% impr. over GMOS

30. MDL GMOS & NAEFS Downscaled Forecast Mean Absolute Error w.r.t. RTMA Average For Sept. 2007 24-h GMOS Forecast 24-h NAEFS Forecast For CONUS: NAEFS(1.45) : GMOS(1.72) 15% impr. over GMOS

31. Surface Temperature MAE CONUS, Sept. 2007 00Z GMOSvs. 00Z NAEFS Surface Temperature MAE CONUS, Sept. 2007 12Z NDFD vs. 00Z MOS/GMOS/NAEFS RTMA Analysis METAR obs. 1221 sites GMOS forecast 0.5°C NAEFS products 0.5°C

32. Surface Temperature Pointwise Bias CONUS, Sept. 2007 00Z GMOSvs. 00Z NAEFS Surface Temperature Area Mean Bias CONUS, Sept. 2007 12Z NDFD vs. 00Z MOS/GMOS/NAEFS Area Mean Bias Pointwise Bias RTMA Analysis METAR obs. 1221 sites GMOS forecast 0.6°C 0.6°C NAEFS products

33. Western Rgn Pointwise Bias Western Rgn Area Mean Bias Western Rgn MAE Western Rgn MAE

34. Central Rgn Pointwise Bias Central Rgn Area Mean Bias Central Rgn MAE Central Rgn MAE

35. Eastern Rgn Area Mean Bias Eastern Rgn Pointwise Bias Eastern Rgn MAE Eastern Rgn MAE

36. Southern Rgn Area Mean Bias Southern Rgn Pointwise Bias Southern Rgn MAE Southern Rgn MAE

37. NCEP-raw NAEFS-final NCEP-raw-downs NCEP-biasc-downs BACK Bo et al.

38. BACKGROUND

39. NFUSE GOALS Need to clarify goals (be)for(e) brainstorming • Premise • We accept and plan to follow major NRC recommendations • What’s needed? • Design, develop, and gradually implement changes in forecast process for assessing, communicating, and using forecast uncertainty • Basic capabilities (by 2009-2010) • Detailed draft plan (including low hanging fruit) by Oct 07 • Full capabilities (by 2012-2017) • Conceptual draft plan by Oct 07 • Corporate commitment • Funding for both phases • Reallocation / reprioritization for phase 1 • PPBES for phase 2 • New / revised operational requirements • Part of planning / development

40. TWO-PHASE PLAN • Phase 1 (2-3 yrs) • Limited time and resources - Build on existing and emerging efforts • Not all users within/outside NWS can access ensemble data • Limited capabilities • Ability to express basic forecasts in probabilistic terms • Uni-variate pdf • Joint probab. computation assumes probabilities for different variables are independent • Other formats derived from uni-variate pdf • Phase 2 (5-10 yrs) • Full capabilities • All interested users within/outside NWS have access to ensemble data • Joint probabilities derived from ensemble • Exhaustive set of forecast formats/products supported

41. BACKGROUND

42. LINKS WITH NFUSE PLANS • Current system • Single value format • Short-term (2-3 yrs) plan – 3 values format (pdf) • Provide best (bias corrected) numerical guidance in agreed upon format • Provide bias corrected ensemble data to external and selected internal users • Human forecasters modify numerical guidance using agreed upon format • Distribute and store agreed upon format • Convert format into single variable pdf format • External users provided with products in format of their choice • Multiple options • Software needed to derive user requested format from single value pdf • Long-term (5-10 yrs) plan – ensemble format • Provide best numerical guidance in agreed upon format • Human forecasters modify numerical guidance using agreed upon format • Propagate information to modify bias corrected ensemble data • Modified bias corrected ensemble data is complete and final forecast dataset includes • Uncertainty information regarding spatial, temporal, cross-variable co-variances • Human forecasters need access to ensemble data to assist in • Manipulation (added value) • Interpretation (user outreach) • External users provided with products in format of their choice • Multiple options • Software needed to derive user requested format from ensemble data

44. SYNERGIES • Choice / acceptance of format for uncertainty info enables inter-comparisons • Verification using common framework possible • Added value can be traced • Choice of THORPEX performance measures • Related to major application areas (previous discussion) • Use 3-value format to verify uncertainty/probabilistic information?

45. INTRODUCTION • Plans need to be coordinated between three major areas • Probabilistic numerical guidance for high impact events (THORPEX) • Provides objective numerical guidance • Human forecasters • Add value to numerical guidance • Interpret guidance / products • Products to be distributed to and used by external community • Interface with “Weather enterprise” • Format of forecast uncertainty estimate can/must link three major areas • Numerical methods • Must be able to produce chosen format • Forecasters • Must be able to manipulate guidance • Must be simple and intuitive • Users • Must find clear value in product given in chosen format • Choice of exact format not critical • As long as software available to generate alternate formats

46. PROPOSED NEW / LEGACY PRODUCTS TO BE MONITORED • Possible new probabilistic guidance products for high impact events • Hydrometeorology • Extreme hydro-meteorological events, incl. dry and wet spells (CONUS) • Exceedance of 1 & 5 inch thresholds • Exceedance of 6-hr flash flood guidance (or numerical outlook) thresholds • Quantitative extreme river flow forecasting (OCONUS) • Tropical / winter storm prediction • Extreme surface wind speed • Radii of gale, storm, hurricane force wind • Maximum surface wind (for intensity) • Extreme precipitation (related to wet spells) • Storm surges • Storm surge values along US Coast • Aviation forecasting • Flight restriction • Icing, visibility, fog, clear air turbulence • Health and public safety • Hot and cold spells • “Legacy” internal probabilistic scores to assess long-term progress • With years of existing archive and/or • Can be easily recomputed • General circulation • Probabilistic 1000 & 500 hPa height forecasts • Tropical storm • Strike probability for track • Probability of intensity (central pressure or wind-based)

47. BACKGROUND

48. NFUSE PRIORITIES? Issues to be discussed/worked out in this order: • NRC Recommendations • Do we agree on major recommendations? • If not, let’s discuss any issues • If so, can we accept those as the basis/guidelines for our work • 3rd Ensemble User Workshop Recommendations • Three major recommendations in response to NRC Report • High level roadmap guiding our collaboration (Sept 2007) • New operational requirements (March 2008) • Design, develop, and gradually implement new forecast process • Basic capabilities (2009-2010) • Full capabilities (2012-2017) • Nine specific recommendations on design, development, implementation • Work areas identified, links to be worked out • Continue development of expanded forecast process • Bias correction & downscaling methods for ensembles • Define summary ensemble information to be used (ST) • Contribute to establishment of NOAA-wide environmental data depository • Develop ensemble interrogation, modification, & product generation tools • Develop telecommunication facilities to access data • Develop unified NWS/NOAA probabilistic verification package (ST) • Develop & implement comprehensive training • Develop outreach program on use & communication of uncertainty Do we need to modify/augment etc these recommendations?

49. Zoltan Toth Environmental Modeling Center NOAA/NWS/NCEP Acknowledgements: NRC Report; Louis Uccellini, Steve Lord & Ensemble Team http://wwwt.emc.ncep.noaa.gov/gmb/ens/index.html COMPLETING THE FORECAST:ASSESSING AND COMMUNICATING FORECAST UNCERTAINTY

50. OUTLINE • REVIEW OF 3RD ENSEMLBE USER WORKSHOP • MAJOR RECOMMENDATIONS REGARDING NRC REPORT • WHAT, WHY, AND HOW TO CHANGE? • SPECIFIC RECOMMENDATIONS