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

Mean Annual Rain (cm) Orlando Ft. Pierce West Palm Beach Miami Naples Spatial Pattern of Rainfall

Rainfall Deviations from Annual Average of 52 inches Rainfall Deviation (inches) Monthly Distribution Wet inches months Dry

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)

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

El Niño Roller Coaster

El Niño / La Niña Effects in South 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

warm cold warm cold Decadal to multi-decadal scale fluctuations in the sea surface temperature (only about 1º F) in the North Atlantic Ocean  Cold Phase (~ , )  Warm Phase ( , 1995-???) Atlantic Multidecadal Oscillation (AMO)

Effect of AMO on South Florida Warm Phase  Wet season rainfall appears to be generally greater. Severe droughts are still possible (remember )  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?

Summary of What We Know (These are tendencies and not absolutes!) RainfallAtlantic Hurricanes Wet SeasonDry Season El Ni ñ o No clear pattern WetterLess activity La Ni ñ a No clear pattern DrierMore activity AMO Warm Phase Wetter decades; drought still possible Greater # of major storms AMO Cold Phase Drier decades; wet years still possible Lesser # of major storms

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

Balancing the Objectives Key Management Objective Lake Level HighLow Protect the integrity of the Dike Protect Estuaries Meet Water Supply needs Maintain a healthy Littoral ZoneNeed lake to be between 12.5' -15.5' Provide water to Everglades Maintain Navigation undesirabledesirable

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

Flood Control Water Shortage Lake Okeechobee Management Zones

WSE Regulation Schedule Operational 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)

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

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

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

Current State POSITION ANALYSIS Stage simulated by a model 95% 50% 25%

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

Questions?