Nowcasting and Short-Term Weather Prediction: A High Priority for the Forecasting Community

1. Nowcasting and Short-Term Weather Prediction: A High Priority for the Forecasting Community Cliff Mass University of Washington

2. Minutes to Hours Although weather prediction on the scale of days and climate prediction over decades and longer are undoubtedly important, only modest emphasis, outside of severe convective forecasting, has been given to the periods of minutes to hours.

3. The Premise • Understanding and predicting weather features on times scales of minutes to hours has the potential for huge societal benefits—saving lives, protecting economic assets, improving the quality of life. • Recent technological and scientific advances have opened the door to huge improvements in short-term diagnosis and prediction as well as the communication of this information to the public.

4. Bottom Line: We need more emphasis on NOWCASTING

5. AMS Nowcasting Definition A description of current weather and a short-term forecast varying from minutes to a few hours; typically shorter than most operational short-range forecasts. American Meteorological Society’s Glossary of Weather and Climate

6. Some Examples of Why We Need It

7. Nowcasting and Auto Accidents

8. More People are Killed or Injured by Auto Accidents Associated with Roadway Icing, Fog, and Heavy Rain Than Any Other Traditional Weather Threat (Floods, Hurricane, Thunderstorms) Consider the statistics of accidents occurring in the presence of rain, sleet, snow and fog, and on wet, snowy, slushy or icy pavement.

9. U.S. Weather-Related Accidents Accidents: 1,561,430 police-reported weather-related accidents per yearInjuries: 673,000 per year on averageFatalities: 7400 per year on averageBottom Line: A quarter of all reported crashes are weather-related, and the National Highway Traffic Safety Administration estimates 57 percent of all weather-related accidents go unreported.

10. State-of-the-art Nowcasting Coupled With New Data Delivery Approaches (smartphones, electronic message boards) Could Reduce the Toll of Death, Injury, and Loss

11. Heavy Rain Crossing Roadways • Many examples of multi-vehicle crashes when convective cells cross roadways. • Leaving the heavy precipitation in daylight often blinds drivers…and major accidents occur, sometimes involving tens of cars/trucks.

12. Nowcasting Solution • Use time extrapolation of intense radar echoes—perhaps providing 10-15 minutes warning lead time. • Use electronic message boards to slow down the traffic and instruct drivers to leave more room for cars in front of them.

13. Multi-vehicle Accidents in Fog and Dust

14. Interstate 10 Dust Storm in ArizonaThree died, 22 vehicles Oct 22, 2009

15. Nowcasting Approaches • Dust-lofting algorithms coupled with real-time observations could predict visibility loss. • Satellite-based observations of dust and fog. • Fog diagnosis from highway observations. • Use of electronic message boards, flow control, and smartphone warning systems to get the message out.

16. Guiding Road Maintenance Crews • Road maintenance crews need real-time information to pre-position trucks with deicer and plows. • This information is often lacking with bad results. • Example: November 22, 2010—Seattle was thrown into gridlock when maintenance crews did not realize severe icing conditions were imminent. • Obvious from weather observations—cold air was surging southward and elevated roadways were covered in slush.

17. Once the traffic locked up, it was too late—some people abandoned cars, others took 12 hr to get home. Probably could have been avoided if real-time weather data was effectively used.

18. Construction • Unexpected weather events cost the construction industry many millions of dollars per year (if not billions). • Some of these losses could be prevented if a short-term warnings of adverse weather were readily available.

19. Local Example: UW Molecular Engineering Bldg. Waterproofing goes on one day

20. Washes off a few hours later

21. Reapplied the Next DayHow Much Did This Cost?

22. Wind Energy

23. The Ramp-Up, Ramp-Down Problem Costs Millions • Current automated forecasts have been poor at predicting steep energy ramps in the short-term • More effective nowcasting would greatly enhanced wind energy’s potential.

24. Predicting Heavy Precipitation Events an Hour in Advance—Perhaps By Temporally Extrapolating Radar-- Could Save Lives and Property December 13, 2006: The Madison Valley Storm One-hour totals December 14, 2006 Nearly 1 inch in an hour

25. Do We Expect Such Events to Increase in Frequency or Intensity Under Global Warming? A woman drowned in her basement and dozens of cars lost.

26. Recreation and Commuting • Should I head out on my bicycle?

27. NO!!!

28. Short-Term Warning For Severe Convection • Obvious and profound benefit. • The one area in which nowcasting is well-developed and often effective.

29. Current Status of Nowcasting • U.S. National Weather Service: not much emphasis except for convective storms • 6-hr basic forecast cycle • Bias towards forecast consistency even when there is a suggestion that reality is going elsewhere. • For significant weather NWS sometimes releases special statements. • Not unusual for short-term forecast and observed weather to be inconsistent.

30. Forecast Released at 8:41 AM Sept 18, 2010

31. Reality: Sunny Warm Morning

33. Infrequently, a short-term forecast is provided

34. Gridded Forecasts Every Three Hours,Updated Every 6 hr, Modified If Necessary

35. The Weather Channel

36. WeatherChannel’s TruPoint (0-6 hr) • TruPoint uses weather radar, satellite, a lightning detection network, weather prediction models, surface sensors and observations to derive the current weather conditions. • Temperature, wind, humidity, precipitation, visibility, and cloud cover are updated several times each hour for points every 1.5 miles across the country.

38. Short-Term Objective Forecast • Start with NWS model output (RUC) as a "first guess." • Statistically combines with geographical data, conventional surface observations, satellite data, Doppler radar, and lightning data to produce the forecast. • Apples quality-control procedures to ensure a sensible weather report/forecast

39. Local TV StationsMorning, noon, dinnertime, and late night updates

40. Radar Temporal Extrapolation: The Predominant Automated Nowcasting Technology NCAR (RAL) AutoNowcaster

41. The Key Ingredients For Next-Generation Nowcasting Are Now Available

42. Ingredients • The Communication Revolution • The Weather Data Revolution • New Generation of Data Assimilation and Modeling Systems • Nowcasting Testbeds

43. The Communication Revolution • Until recently, a major problem for nowcasting was the inability to get weather information rapidly to users…quickly enough for decision making. • But that has all changed now.

44. First, PCs Connected to the InternetHardwired, WIFI, or 3G

45. Today Smartphones Offer a Powerful, Portable Platform for Viewing Weather Information, Forecasts, and Warnings

46. Smartphones are Ideal! • Lots of bandwidth • They know where they are, so forecast information can be tailored to the user • Substantial computational capacity.

47. And other real-time delivery approaches now exist

48. The Weather Data Revolution • Exponential increase in surface and upper air data has given us a highly detailed view of the conditions at the surface over land. • Extraordinary number of new surface networks, from highway departments and air quality agencies, to utility companies and local governments. • Plus amateurs with good weather stations on the internet.

49. Example: The Pacific Northwest Based on 72 different networks 3000-4000 observations per hour over WA and OR

50. And much more.. • ACARS and TAMDAR data from aircraft flying in and out of airports.