Climate: Outlook and Operational Planning

1. Climate: Outlook and Operational Planning Jayantha Obeysekera (’Obey’), Ph.D.,P.E.,D.WRE Department Director Hydrologic & Environmental Systems Modeling

2. Orlando Ft. Pierce West Palm Beach Naples Mean Annual Rain (cm) Miami 48 50 55 60 Spatial Pattern of Rainfall

3. Wet Dry inches MonthlyDistribution months Rainfall Deviations from Annual Average of 52 inches Rainfall Deviation (inches) 1965-1995

4. Weather vs. Climate • Weather pertains to occurrences from hour to hour, or day to day, in a specific location • Forecasting: Typical lead time up to few hours to a week • Climate pertains to average weather over an extended period of time • Outlook: Typical lead time ranges from weeks to multiple seasons (e.g. remainder of the wet season + dry season) • Based on “Teleconnections”: El Niño-Southern Oscillation (ENSO) and Atlantic Multidecadal Oscillation (AMO)

5. El Niño – Southern Oscillation (ENSO) • An oscillation in the ocean-atmosphere system in the Equatorial Pacific • Generally 3-7 year “cycle” • El Niño: warmer than normal ocean temperatures • La Niña: colder than normal ocean temperatures

6. El Niño Roller Coaster

7. El Niño / La Niña Effects inSouth Florida • El Niño: Greater chance of wetter than normal rainfall during dry season months • La Niña: Greater chance of drier than normal rainfall during dry season months • No clear tendency in wet season months • Less Atlantic tropical storm activity during El Niño and more during La Niña

8. warm warm cold cold Atlantic Multidecadal Oscillation (AMO) • Decadal to multi-decadal scale fluctuations in the sea surface temperature (only about 1º F) in the North Atlantic Ocean • Cold Phase (~1900-1925, 1970-1994) • Warm Phase (1926-1969, 1995-???)

9. Effect of AMO on South Florida • Warm Phase • Wet season rainfall appears to be generally greater. Severe droughts are still possible (remember 2000-2001) • The number of tropical storms that mature into major hurricanes is greater • ENSO effect is reinforced during Feb-March period • Cold Phase • Rainfall generally below the long term average. Wet years are still possible • Unknown: When will it switch from the current warm phase to cold phase?

10. Summary of What We Know(These are tendencies and not absolutes!)

11. Operational Planning • Operational decisions today may significantly influence the system conditions months from now. Tools are needed to look ahead. • Tools of Operational Planning • Climate Outlook and associated uncertainties • Operating rules which incorporate climate outlooks • Computer models to simulate future possible scenarios

12. Balancing the Objectives undesirable desirable

13. Achieving Balance:Tools for Managing Lake Okeechobee • Water Supply and Environment (WSE) Regulation Schedule • Manages high stages • Designed to preserve flood protection and balance competing objectives • Water Shortage Plan • Manages low lake stages • Designed to ration water supplies during extended dry periods

14. Water Shortage Lake Okeechobee Management Zones Flood Control

15. WSE Regulation ScheduleOperational Elements • Lake Okeechobee Water Level • Tributary Hydrologic Condition • 30 Day Net Rainfall • Average Kissimmee River (Tributary watershed) inflow • Lake Okeechobee Net Inflow Outlook • Seasonal Outlook (6 month) • Multi-seasonal Outlook (7 to 12 months)

16. WSE Operational Guidelines Decision Tree Part 2: Define Lake Okeechobee Discharges to Tidewater (Estuaries) Apply Tributary Condition Criteria Weekly Check Special Lake Criteria daily as needed for Zones B & D Apply Meteorological Forecasts on a Weekly Basis; apply Seasonal and Multi-Seasonal Climate Outlooks on a Monthly Basis Up to Maximum Discharge Capacity To Tidewater ZONE A Up to 30 day Meteorological Forecast EXTREMELY WET Zone B Steady Flow S-80 Up to 3500cfs S-77 Up to 6500cfs Tributary Hydrologic Conditions WET TO VERY WET NORMAL TO VERY WET Seasonal Climate Outlook ZONE B Up to Maximum Pulse Release to the Estuaries NORMAL TO VERY WET FALSE NORMAL TO DRY Up to 30 day Meteorological Forecast Lake Less than 17.5’ & it’s the Dry Season TRUE DRY DRY START Lake Okeechobee Water Level Up to Zone B S-80 Up to 3500cfs S-77 Up to 6500cfs Up to 30 day Meteorological Forecast EXTREMELY WET WET TO VERY WET Zone C Steady Flow S-80 Up to 2500cfs S-77 Up to 4500cfs Tributary Hydrologic Conditions WET TO VERY WET NORMAL TO DRY ZONE C EITHER FORECAST INDICATES WET TO VERY WET Up to Maximum Pulse Release to the Estuaries NORMAL TO VERY WET Seasonal Climate Outlook Multi- Seasonal Climate Outlook NORMAL TO DRY BOTH FORECASTS INDICATE NORMAL TO DRY No Discharge to Tidewater & Meteorological Forecast DRY Lake Stage within 0.5 feet of Zone C Seasonal Climate Outlook Up to Zone C S-80 Up to 2500cfs S-77 Up to 4500cfs EXTREMELY WET VERY WET TRUE Tributary Hydrologic Conditions OTHERWISE WET TO VERY WET FALSE ZONE D TRUE NORMAL Seasonal Climate Outlook Lake Stage within 0.5 feet of Zone C Multi- Seasonal Climate Outlook WET TO VERY WET Up to Maximum Pulse Release to the Estuaries FALSE VERY WET OTHERWISE DRY NORMAL TO DRY No Discharge to Tidewater

17. WSE Operational Guidelines Decision Tree Part 2: Define Lake Okeechobee Discharges to Tidewater (Estuaries) 16.75 16.5 (Zone C) 16.25 DRY DRY DRY 6 3 1 Apply Tributary Condition Criteria Weekly Check Special Lake Criteria daily as needed for Zones B & D Apply Meteorological Forecasts on a Weekly Basis; apply Seasonal and Multi-Seasonal Climate Outlooks on a Monthly Basis Up to Maximum Discharge Capacity To Tidewater ZONE A Up to 30 day Meteorological Forecast EXTREMELY WET Zone B Steady Flow S-80 Up to 3500cfs S-77 Up to 6500cfs Tributary Hydrologic Conditions WET TO VERY WET NORMAL TO VERY WET Seasonal Climate Outlook ZONE B Up to Maximum Pulse Release to the Estuaries NORMAL TO VERY WET FALSE NORMAL TO DRY Up to 30 day Meteorological Forecast Lake Less than 17.5’ & it’s the Dry Season TRUE DRY DRY START Lake Okeechobee Water Level Up to Zone B S-80 Up to 3500cfs S-77 Up to 6500cfs Up to 30 day Meteorological Forecast EXTREMELY WET WET TO VERY WET Zone C Steady Flow S-80 Up to 2500cfs S-77 Up to 4500cfs Tributary Hydrologic Conditions WET TO VERY WET NORMAL TO DRY ZONE C EITHER FORECAST INDICATES WET TO VERY WET Up to Maximum Pulse Release to the Estuaries NORMAL TO VERY WET Seasonal Climate Outlook Multi- Seasonal Climate Outlook NORMAL TO DRY BOTH FORECASTS INDICATE NORMAL TO DRY No Discharge to Tidewater & Meteorological Forecast DRY Lake Stage within 0.5 feet of Zone C Seasonal Climate Outlook Up to Zone C S-80 Up to 2500cfs S-77 Up to 4500cfs EXTREMELY WET VERY WET TRUE Tributary Hydrologic Conditions OTHERWISE WET TO VERY WET FALSE ZONE D TRUE NORMAL Seasonal Climate Outlook Lake Stage within 0.5 feet of Zone C Multi- Seasonal Climate Outlook WET TO VERY WET Up to Maximum Pulse Release to the Estuaries FALSE VERY WET OTHERWISE DRY NORMAL TO DRY No Discharge to Tidewater

18. Weekly Implementation • Tributary Hydrologic Condition • Based on past 4-week net rainfall and past 2-week mean inflows from Kissimmee Basin • 6 Classes: Very Dry to Extremely Wet • Climate Outlook • Net Inflow = Inflow + Rainfall – Evapotranspiration converted to equivalent depth • Outlook classes: Dry, Normal, Wet, Very Wet • 6 month Seasonal Outlook • 7-12 month Multi-seasonal Outlook

19. Current State Stage simulated by a model 1969 95% 1984 50% 1975 25% 1970 1989 POSITION ANALYSIS

20. Lake Okeechobee August 1st, 2007 Position Analysis (preliminary)

21. Questions?