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User-driven Climate Forecasts in the Southeast U.S.

David F. Zierden Assistant State Climatologist Center for Ocean-Atmospheric Prediction Studies The Florida State University Tallahassee, FL. User-driven Climate Forecasts in the Southeast U.S. World Map. ENSO Impacts in the Southeast. EL Niño Very wet winter and spring

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User-driven Climate Forecasts in the Southeast U.S.

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  1. David F. Zierden Assistant State Climatologist Center for Ocean-Atmospheric Prediction Studies The Florida State University Tallahassee, FL User-driven Climate Forecasts in the Southeast U.S.

  2. World Map

  3. ENSO Impacts in the Southeast • EL Niño • Very wet winter and spring • Greatly reduces Atlantic • hurricanes • decreases tornadoes in • the tornado alley • La Niña • Dry Fall, Winter, and Spring • Greatly increases Atlantic • hurricanes • Increases tornadoes in • the deep south • Greatly increases wildfire • activity Neutral ENSO phase increases the risk of severe freezes by 3:1 odds.

  4. ENSO Effects on Precipitation

  5. ENSO Effects on Temperature

  6. Impact Freezes of the last century Freeze Date ENSO State *Dec 1894 Neutral Feb 1899 Neutral Dec 1934 Neutral Jan 1940 Neutral *Dec 1961 Neutral Jan 1977 El Nino Jan 1981 Neutral *Dec 1983 Neutral Jan 1985 Neutral *Dec 1989 Neutral Jan 1997 Neutral * High Impact

  7. ENSO and Florida FreezeProbabilites

  8. Return Frequencies

  9. Extended Freeze Events

  10. Late Season Freezes

  11. La Niña and Wildfires April • La Niña brings drier than normal conditions (30%-40%) and warmer temperatures from November through April. • Wildfire activity is increased throughout the wildfire season. • The increased activity can be expected during nearly all La Niña episodes. Anomalous Wildfire activity (acres burned) during La Niña episodes

  12. Mallory Swamp Fire during the last La Niña

  13. Forecasting Potential Wildfire Activity • Forecast based on the Keetch-Byram Drought Index (KBDI). • Historical weather observations from the NWS Coop network provides coverage at nearly county level. • Forecast is presented in probabilistic terms. • “Bootstrapping” used to generate probability distributions for each station.

  14. KBDI Forecast Method

  15. Wildfire Threat forecast • The end product is a monthly, county-by-county forecast of the KBDI. • Graphic shows the probability of at least 7 days in the month being above or below critical thresholds. • Thresholds were determined with input from forestry and wildfire experts. • Forecast was based on the Neutral ENSO phase.

  16. More uses for climate forecasts that just wildfire • Harvesting - cannot harvest in low areas during El Nino winters. • Planting - Survival rate low during La Nina • Managed Forests - Herbicides, pesticides, prescribed burns

  17. Visit Our Websites COAPS: www.coaps.fsu.edu Florida Climate Center: www.coaps.fsu.edu/climate_center Florida Automated Weather Network: fawn.ifas.ufl.edu For More Information:

  18. Determining Probability Distributions using “Bootstrapped” Data • Begin with the CURRENT KBDI value at the beginning of the forecast cycle. • Use over 50 years of DAILY observations at each station (13 El Nino, 13 La Nina, and 28 neutral). • Constuct a “bootstrapped” month by randomly selecting temperature and precipitation values each day from the group with similar ENSO phase. • Repeat until you have 1,000 realizations of the specific ENSO phase in each month.

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