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Week 13 Notes

TONIGHT Weather Forecasting ( Chp 14) Nov 23 No Class – Fall Recess Nov 30 Earth’s Changing Climate ( Chp 15) Review Term Papers Due Dec 7 FINAL EXAM Extra Credit Term Papers Due. Week 13 Notes. CHAPTER 14 WEATHER FORECASTING. Classwork (HW#11). Divide into 6 groups

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Week 13 Notes

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  1. TONIGHT • Weather Forecasting (Chp 14) • Nov 23 • No Class – Fall Recess • Nov 30 • Earth’s Changing Climate (Chp 15) • Review • Term Papers Due • Dec 7 • FINAL EXAM • Extra Credit Term Papers Due Week 13 Notes

  2. CHAPTER 14 WEATHER FORECASTING

  3. Classwork (HW#11) • Divide into 6 groups • Find 2 different forecasts for Saturday, Nov. 20 • Groups 1 & 4: Seattle • Groups 2 & 5: Reno • Groups 3 & 6: San Francisco • What sites did you use? Why? • Discuss what was forecast. • How were they different?

  4. Weather Forecasting in US • Ben Franklin • Used Post Service • 1870s Congress Established Weather Services • Branch of Army Signal Corps • 1890 Transferred to Department of Agriculture • US Weather Bureau • 1942 Transferred to Department of Commerce • 1970 National Oceanic and Atmospheric Administration (NOAA) • Renamed National Weather Service (NWS)

  5. Forecast Methods • Persistence • Trend (Steady State) • Climatology • Interpolation • Analogue • Weather Types • Numerical Weather Prediction (NWP)

  6. Climatology Fig. 14.8, p. 409

  7. Numerical Weather Prediction • Model Inputs (Initial Conditions) • Temperature • Moisture • Wind • Pressure

  8. Numerical Weather Prediction • Initial Conditions • Surface • Airports • Auto Remote Weather Stations • Buoys • Ships • Upper Air • Radiosondes • Satellite Sounders • Aircraft

  9. Numerical Weather Prediction • Interpolation of Initial Conditions • Horizontal Grids • Vertical Grids • Other Inputs • Topography • Date/Season • Ground Cover • Numerical Models • Time Step Forward • 12, 24, 36, 48…384hrs

  10. NAM Numerical Model • Semi-staggered Arakawa E grid • 32km horizontal resolution • 45 vertical eta layers

  11. NAM Numerical Model • Now do it in 3-D

  12. Numerical Weather Prediction • Some of the Current Models • NAM/WRF • NGM (Nested Grid) • GFS (Global Forecast System) • Meso-ETA • MM5 • RUC • UK • ECMWF • NOGAPS • Ensemble Forecasts

  13. NAM Numerical Model

  14. ETA Topography

  15. GFS Topography

  16. Numerical Weather Prediction • Model Outputs • Raw Data • Temperature • Pressure • Moisture • Derived Outputs • Wind (x,y,z) • Stability • Vorticity • Precipitation • MOS • Model Output Statistics

  17. NWP Output - Raw

  18. NWP Output - Raw

  19. NWP Output - Raw

  20. NWP Output - Raw

  21. NWP Output - Derived

  22. Day 2 Ensemble Forecasts

  23. Day 5 Ensemble Forecasts

  24. Day 8 Ensemble Forecasts

  25. Day 11 Ensemble Forecasts

  26. Rainfall Forecasts & Resolution

  27. Human Output

  28. MOS Output KOAK AVN MOS GUIDANCE 3/24/2003 0600 UTC DT /MAR 24 /MAR 25 /MAR 26 / HR 12 15 18 21 00 03 06 09 12 15 18 21 00 03 06 09 12 15 18 00 06 X/N 64 49 66 55 64 TMP 51 51 56 61 62 57 54 52 51 52 58 64 64 59 57 57 56 58 60 62 55 DPT 46 45 45 44 44 45 45 45 44 44 47 48 50 51 52 52 52 51 49 45 43 CLD BK BK SC SC CL CL CL CL SC SC BK BK OV OV OV OV OV OV BK SC CL WDR 28 27 26 27 28 28 30 29 31 28 23 26 26 27 26 24 25 24 26 27 31 WSP 07 07 09 11 12 10 05 04 01 01 03 08 12 13 07 09 10 10 10 15 09

  29. Types of Forecasts • Quantitative Forecast Amount of Forecast Variable Is Specified An Inch of Rain High Temperature Will Be 45°F • Qualitative Forecast Categorical Value for Forecast Variable Above / Below Normal Cloudy / Partly Cloudy / Mostly Cloudy • Probability Forecast Chance of Something Happening Rather Than a Certainty Cloud Cover Will be 70% Probability of PrecipitationPoP Forecast 75% Chance of Rain Odds of Precipitation Are 3:1

  30. Weather Products • Public Forecasts • Weather • Temperatures • Wind • Advisories • Types of Forecasts • Now cast < 6 hrs • Short range 12-72 hrs • Medium range 3 - 8.5 days • Long Range > 8.5 days

  31. Weather Products • Aviation Forecasts • Terminal Conditions • EnrouteConditions • Marine Forecasts • Winds • Seas • Swells • Weather

  32. Watches and Warnings • Advisories • Less Severe • Dense Fog, Wind, Urban Flooding • Watches (usually 6-24 hours in advance) • Possible Severe Weather • Tornadoes, Severe Thunderstorms, Flash Flooding • Warnings (imminent or occurring) • Probable Severe Weather • Tornadoes, Severe Thunderstorms, Flash Flooding

  33. Specialized Weather Products • Fire Weather Forecasts • Weather • Temperatures • Wind • Humidity • Agricultural Forecasts • Frosts and Freezes • Temperatures • Precipitation • Flood Forecasts • Avalanche Forecasts

  34. Weather Dissemination • Where do you get weather information? • How reliable is it?

  35. Weather Forecast Sources • National Weather Service • NCEP • Digital data • Long range • Local Offices • Public, Aviation, Marine Forecasts • Private Weather Companies • Media • Electronic • Print • Internet

  36. Making a Forecast • Initial Conditions • Satellite • Radar • Surface observations • Look at the models • Forecasts discussions • Other forecasts

  37. Making a Forecast http://ggweather.com/4cast.htm

  38. What is a Meteorologist? • Do you have to have a degree in meteorology? • Who certifies? • Television meteorologists? • Other careers: • Academia • Research • Applied • Forensic

  39. Forecast Accuracy • What to Verify? When to Verify? Who to Verify? • Temperature • Rain • Probability • Amount • Storminess • Bay Area Storm Index (BASI) • Farmer’s Almanac ?

  40. Forecast Accountability • Suing the Weatherperson • Bad hair day? Ruined Picnic? Cancelled Concert? • Brazil • “Sounding a False Alarm” • Peru • 10 inches of Rain, Floods and 17 Drowned • “Sovereign Immunity” • Federal Tort Claims Act • Negligence or wrongful act or omission • Private vs. Government Forecasts

  41. NO CLASS NEXT WEEK!! HAPPY THANKSGIVING

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