1. Summer 2010 Forecast

2. Outline Review seasonal predictors Focus on two predictors: ENSO Soil moisture Summer forecast Look back at winter forecast Questions © AER 2010 – All Rights Reserved

3. Seasonal Forecasting Tools Climatology - Past history is used to predict the future. Persistence - Extrapolating recent past into the future. El Nino/Southern Oscillation - The most important recent discovery which has improved seasonal climate forecasts. Trends - Extrapolating multi-year and multi- decadal trends into the future. Soil moisture - In summer dry soil is associated with warm temperatures and vice versa. Atmospheric precursors – Using regional anomalies in sea level pressure, wave energy, etc. to predict future large-scale atmospheric patterns. Snow cover (winter months only) - Extensive snow cover is conducive to cold air masses.

4. © AER 2010 – All Rights Reserved Equatorial Pacific Warm sea surface temperature anomalies dominate the eastern equatorial Pacific though anomalies are weakening.

5. © AER 2010 – All Rights Reserved ENSO Forecast Forecast models all predicting El Niño conditions to wane during the spring and summer.

6. © AER 2010 – All Rights Reserved Soil Moisture Wet in the South, the East Coast and the Plains with dry in the West and the Great Lakes.

7. © AER 2010 – All Rights Reserved Summer Temperature Forecast

8. © AER 2010 – All Rights Reserved Summer Precipitation Forecast

9. Verification of Winter Forecast © AER 2010 – All Rights Reserved

10. October Siberian Snow Cover During the last 3 weeks of October 2009 there was a rapid increase in Siberian snow cover… …that was equivalent to the snow cover advance across North America from September through January

11. © AER 2010 – All Rights Reserved 2009/10 Winter Temperatures

12. © AER 2010 – All Rights Reserved El Niño, Snow & Winter Temperatures

13. © AER 2010 – All Rights Reserved Anomaly Correlation - a measure of how well the forecast compares to the observations at one point for all the available forecasts. For the real-time forecasts there are a total of 37 forecasts. 37 years of hindcasts for sCast model Skill Score – a measure of how well the forecast compares to a forecast derived from climatology. Forecast Verification

14. © AER 2010 – All Rights Reserved City Forecasts

15. © AER 2010 – All Rights Reserved 2009/10 Winter Temperatures

16. © AER 2010 – All Rights Reserved 2009 Winter Precipitation

17. © AER 2010 – All Rights Reserved AER Summer Forecast Weakening El Nino is predicted for the summer, this is usually associated with less heat ridging in the interior US and somewhat wetter, consistent with model precipitation forecast. Soil moisture is wet in the South and in the Plains with dry in the Great Lakes and in the Pacific Northwest. This favors warmer temperatures in the Northeastern quadrant of the country and the West with cooler in the South and the Plains. Thank You!