Forecasts for early action

1. Forecasts for early action

2. Objectives of this session • Increase understanding of forecast information • Describe how short, medium and seasonal forecasts can be used for early action

3. Outline: Forecasts • What? • How? • Who? • When? • Why? • What makes a good forecast? • How well can we predict extreme events? Mongolia, Early Action for Dzud February 2018

4. What? What is a forecast? The forecast is a statement explaining what meteorological conditions we can expect: • for a specified time • for a specified location It often provides information on the likelihood or probability of an event happening (e.g. 50% chance of rain tomorrow in a specific location).

5. How? How are forecasts made? Forecasters use many sources of information to predict what will happen next: • Current and recent weather conditions • Models of how air and water move around (called dynamical computer models) • Past data on which conditions have been linked to which events (called statistical models) • Expert judgement Traditional local forecasts are made based on observing current conditions, locally-known indicators, and using expert judgement.

6. Who? National forecasting institutes Collectively referred to as National Meteorological and Hydrological Services (NMHS), national government meteorological (or ‘Met’) services and national level hydrological (or ‘Hydro’) services often have the best information on climate and weather for humanitarian use.

7. Who? Regional foreacasting centres

8. Who? International products

9. When? How far ahead can we forecast?

10. When? How far ahead can we forecast?

11. Why? How are forecasts used? Using climate science can help Governments and humanitarian organizations to protect the lives, livelihoods and infrastructure of people around the world, particularly the most vulnerable.

12. How are forecasts used? Weather forecasts are used throughout society to help people! Here are some common ways that weather forecasts are used: 1. Businesses and people plan for power production and how much power to use (i.e. power companies, where to set thermostat) 2. Prepare for extreme weather (i.e. umbrella, rain coat, sun screen) 3. Plan outdoor activities (i.e. to see if rain/storms/cold weather will impact outdoor event) 4. Farmers and gardeners plan for crop irrigation and protection (irrigation scheduling, freeze protection)

13. Why? We can anticipate hazard events. If we can use forecasts to anticipate a hazard, we can take early action to prepare for a potential disaster.

14. Forecasts can helpinform Early actions If we can use forecasts to anticipate a hazard, we can take early action to prepare for a potential disaster. Source: ODI 2019. Scaling FbF in Kenya study Source: ODI 2019. Scaling FbF in Kenya study Source: ODI 2019. Scaling FbF in Kenya study Source: ODI 2019. Scaling FbF in Kenya study

15. What makes a good forecast? What do you consider a “good” or “bad” forecast, and why?

16. What makes a good forecast? Consistency Value Quality

17. When might a forecaster say something different from what he/ she really thinks will happen?

18. What makes a “good” forecast? Forecast: Joey Chestnut will win the hot dog eating contest in the US in 2019. Verification: Who cares? Forecasts are only useful when they have value.

19. Are we forecasting something of value?

20. What makes a “good” forecast? Forecast: Tomorrow the water level will be 2.3 meters. Verification: It was 2.5 meters. If the forecast is above the danger level and the event happens, then this is a hit!

21. What makes a good forecast?

22. What makes a “good” forecast? Forecast: 20% chance of rain tomorrow. Verification: It rained every time I issued a 20% forecast. I should have issued a 100% forecast. My probabilities were not reliable. .

23. Forecast skill around the world How well can we predict heatwaves?

24. Where can we prepare seasonally for heatwaves?

25. Where can we take action on heatwave forecasts?

26. How well can we predict coldwaves? Forecast skill around the world

27. Where can we prepare seasonally for coldwaves?

28. Where can we take action on coldwave forecasts?

29. How well can we predict cyclones? Cyclones, hurricanes, typhoons.

31. How well can we predict floods? Flash floods are very difficult to predict. If a hydrological model is available in your area, it can usually predict floods on big rivers several days or weeks in advance.

32. Global map of reservoirs and dams Source: Global Reservoirs and Dams

33. How well can we predict drought? Drought is a complex disaster, and “drought” means different things to different people

34. How well can we predict drought? Seasonal rainfall forecasts can help us predict droughts. Here is a map of how useful seasonal rainfall forecasts can be when they predict dry/wet for different parts of the world. Dry Dec-Jan-Feb Wet Dec-Jan-Feb Wet Jun-Jul-Aug Dry Jun-Jul-Aug

35. Common myths about forecasts Consensus forecasting’ is the best approach All mathematical approaches work from the assumption that the future is more or less like the past, which is often not the case. Rainy rooster Another bird-related bit of lore, it has been thought that hearing a rooster crow at night is a sure sign that there will be rain by morning. Cricket thermometer It has been said that listening to a cricket’s chirp can give you an idea of the temperature outside. Could there be any validity to this? Lightning never strikes the same place twice We’ve all heard this old refrain. But is there any truth behind it?