1. NOAA Seasonal Drought Outlooks: Status and Progress Douglas Le Comte SRH/ERH Climate Workshop Peachtree City, GA June 2007

2. Outline Current Techniques for Drought ForecastingCurrent Techniques for Drought Forecasting A closer look at the tools used to forecast the Southeast DroughtA closer look at the tools used to forecast the Southeast Drought Ideas for the future of drought forecastingIdeas for the future of drought forecasting

3. New Forecast Tool Cambodian royal cows predict drought, poor harvest this year (2007/5/6 PHNOM PENH, AFP)Cambodian royal cows predict drought, poor harvest this year (2007/5/6 PHNOM PENH, AFP) PHNOM PENH PHNOM PENH Cambodia's royal cows signaled a drought and poor harvests in an ancient ceremony Saturday to mark the beginning of the kingdom's planting season.Cambodia's royal cows signaled a drought and poor harvests in an ancient ceremony Saturday to mark the beginning of the kingdom's planting season.Cambodia's

4. Recent Draft Drought Outlook

5. The Three Pillars of the Forecast Two-week soil moisture forecastsTwo-week soil moisture forecasts Climatology: Palmer probabilities, analogues, compositesClimatology: Palmer probabilities, analogues, composites Seasonal temperature, precipitation, and soil moisture forecastsSeasonal temperature, precipitation, and soil moisture forecasts

6. Features of the Seasonal Drought Outlook A schematic designed to provide a broad indication of drought trends for the following ~3 monthsA schematic designed to provide a broad indication of drought trends for the following ~3 months Four categories: improve, some improvement (e.g., better soil moisture and grassland growth but continuing water supply shortages), persist/worsen, developmentFour categories: improve, some improvement (e.g., better soil moisture and grassland growth but continuing water supply shortages), persist/worsen, development Issued 3 rd and 1 st Thursday each month (NEW!)Issued 3 rd and 1 st Thursday each month (NEW!) Incorporates forecasts from all time periodsIncorporates forecasts from all time periods Starts with the most recent U.S. Drought monitor D1 areasStarts with the most recent U.S. Drought monitor D1 areas

7. 2-Wk Soil Moisture Constructed Analogue Soil Model Medium-Range Fcst Palmer 4-mo Probabilities CPC Long-Lead Precip. Outlook Principal Drought Outlook Inputs

8. Selected Forecast Tools “These are some of my favorite things.”

9. CPC 2-Week Soil Moisture Forecast http://www.cpc.noaa.gov/products/soilmst/mrf.shtml

10. Constructed Analogues from Soil (CAS) Moisture http://www.cpc.noaa.gov/products/soilmst/forecasts.shtml

11. CFS Modeled Soil Moisture http://www.cpc.ncep.noaa.gov/products/people/wwang/cfs_fcst/

12. Palmer Probability Data September Palmer Probabilities http://www.ncdc.noaa.gov/oa/climate/research/drought/current.html

13. Historical Analogues: Soil Moisture June 1 Oct. 1 2000 1987 http://www.hydro.washington.edu/forecast/monitor/index.shtml

14. Historical Analogues June 1 Oct. 1 1986 1985

15. Drought Composites Jun-Sep: Palmers Rainfall Temperatures June PDI Sep PDI

16. Mean score=49% Mean improvement over persistence =13% Verification: Percent Area Correct

17. Two Path Drought Forecast Approach Continue current schematic for the general publicContinue current schematic for the general public Produce objective probability maps for technical usersProduce objective probability maps for technical users

18. Near-term Changes to Drought Outlook Have increased frequency to twice/monthHave increased frequency to twice/month Propose adjustment of forecast categories so all categories can be verified (include category for intensification?)Propose adjustment of forecast categories so all categories can be verified (include category for intensification?) Propose using more current GFS ensemble runs for soil moisture forecasts and initializing CAS with 2-week forecastPropose using more current GFS ensemble runs for soil moisture forecasts and initializing CAS with 2-week forecast Considering drought probability mapConsidering drought probability map

19. Proposed Category Change

20. Possible Probability Map

21. Drought Recovery Prediction Methodology Use observed forcings to drive the model and produce “best knowledge” initial conditions for forecastUse observed forcings to drive the model and produce “best knowledge” initial conditions for forecast Drive the model with precipitation and temperature forcings unconditionally sampled from climatology creating an ensemble of model trajectoriesDrive the model with precipitation and temperature forcings unconditionally sampled from climatology creating an ensemble of model trajectories At different lead times, estimate probability of soil moisture/runoff percentile exceeding threshold from ensemble = probability of recoveryAt different lead times, estimate probability of soil moisture/runoff percentile exceeding threshold from ensemble = probability of recovery Prototype forecast product from UW

22. Probability of Drought Recovery Initial Conditions (2/2006) 1-month lead forecast (3/2006) 6-month lead forecast (8/2006) 3-month lead forecast (5/2006) Prototype forecast product from UW

23. Current Princeton Probability Forecasts

24. Thoughts for the Future Statistical and dynamic (GCM) techniques can be used to forecast the probabilities for reaching various levels of the drought variable—need to effectively combine ST and LT forecastsStatistical and dynamic (GCM) techniques can be used to forecast the probabilities for reaching various levels of the drought variable—need to effectively combine ST and LT forecasts For a drought early warning system, need to consider current conditions, trends, and forecastsFor a drought early warning system, need to consider current conditions, trends, and forecasts Effective early warning systems (DEWS) provide alerts (e.g. watch, warning) and assessment, not just data. “Alert” for developing droughts? “Advisories” for ongoing droughts?Effective early warning systems (DEWS) provide alerts (e.g. watch, warning) and assessment, not just data. “Alert” for developing droughts? “Advisories” for ongoing droughts? Do we ring a bell for drought?