climate: outlook and operational planning jayantha obeysekera (’obey’), ph.d.,p.e.,d.wre...

Climate: Outlook and Operational Planning

Jayantha Obeysekera (’Obey’), Ph.D.,P.E.,D.WRE

Department Director

Hydrologic & Environmental Systems Modeling

Mean AnnualRain (cm)

48

505560

Orlando

Ft. Pierce

WestPalmBeach

Miami

Naples

Spatial Pattern of Rainfall

6566

676869

707172 73

7475

76 7778

7980 81

8283

8485

8687

88

9091

92 93

95

89

94

-15

-10

-5

0

5

10

15

20

Rainfall Deviations from Annual Average of 52 inches

1965-1995

Rai

nfa

ll D

evia

tio

n (

inch

es)

MonthlyDistribution Ja

n

Feb Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

0

1

2

3

4

5

6

7

8

9

10Wet

inch

es

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 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

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 (~1900-1925, 1970-1994)

Warm Phase (1926-1969, 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 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?

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

Rainfall Atlantic HurricanesWet Season Dry Season

El Niño No clear pattern

Wetter Less activity

La Niña No clear pattern

Drier More 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

High Low

Protect the integrity of the Dike

Protect Estuaries

Meet Water Supply needs

Maintain a healthy Littoral Zone Need lake to be between 12.5' -15.5'

Provide water to Everglades

Maintain Navigation

undesirable desirable

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 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)

& MeteorologicalForecast

Seasonal Climate Outlook

TributaryHydrologicConditions Multi-

SeasonalClimateOutlook

No Dischargeto Tidewater

Up to Maximum Pulse Release

to the Estuaries


Up to Maximum Discharge Capacity

To Tidewater

WSE Operational Guidelines Decision TreePart 2: Define Lake Okeechobee Discharges to Tidewater (Estuaries)

Apply TributaryCondition

Criteria Weekly


Criteria Weekly

Apply Meteorological Forecasts on aWeekly Basis; apply Seasonal and Multi-Seasonal Climate Outlooks

on a Monthly Basis


on a Monthly Basis

Check Special LakeCriteria daily as needed

for Zones B & D


for Zones B & D

STARTLake Okeechobee

Water Level

ZONE A

DRY

VERY WET

ZONE B

ZONE C

ZONE D

TributaryHydrologicConditions


Lake Stagewithin 0.5 feet

of Zone C


of Zone C



Multi-SeasonalClimateOutlook

Zone C Steady FlowS-80 Up to 2500cfsS-77 Up to 4500cfs


to the Estuaries

Zone B Steady FlowS-80 Up to 3500cfsS-77 Up to 6500cfs

Up to 30 dayMeteorological

Forecast

LakeLess than 17.5’ & it’s the Dry

Season


Forecast

Up to Zone BS-80 Up to 3500cfsS-77 Up to 6500cfs

Up to Zone CS-80 Up to 2500cfsS-77 Up to 4500cfs


to the Estuaries



Forecast

WET TO VERY WET

NO

RM

AL

EXTREMELY WET TRUE

FALSE

FALSE

TRUE

OTHERWISE

WET TO VERY WET

NORMAL TO DRY

VERY WET

OTHERWISE

NORMAL TO DRY

WET TO VERY WET

EXTREMELY WETWET 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

& MeteorologicalForecast

Seasonal Climate Outlook

TributaryHydrologicConditions Multi-




to the Estuaries


Up to Maximum Discharge Capacity

To Tidewater

WSE Operational Guidelines Decision TreePart 2: Define Lake Okeechobee Discharges to Tidewater (Estuaries)


Criteria Weekly


Criteria Weekly


on a Monthly Basis


on a Monthly Basis


for Zones B & D


for Zones B & D

STARTLake Okeechobee

Water Level

ZONE A

DRY

VERY WET

ZONE B

ZONE C

ZONE D




of Zone C


of Zone C



Multi-SeasonalClimateOutlook

Zone C Steady FlowS-80 Up to 2500cfsS-77 Up to 4500cfs


to the Estuaries

Zone B Steady FlowS-80 Up to 3500cfsS-77 Up to 6500cfs


Forecast

LakeLess than 17.5’ & it’s the Dry

Season


Forecast

Up to Zone BS-80 Up to 3500cfsS-77 Up to 6500cfs

Up to Zone CS-80 Up to 2500cfsS-77 Up to 4500cfs


to the Estuaries



Forecast

WET TO VERY WET

NO

RM

AL

EXTREMELY WET TRUE

FALSE

FALSE

TRUE

OTHERWISE

WET TO VERY WET

NORMAL TO DRY

VERY WET

OTHERWISE

NORMAL TO DRY

WET TO VERY WET

EXTREMELY WETWET 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 DRY

DRY

631

16.75

16.25

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

9.0

11.0

13.0

15.0

17.0

19.0

J-98 A-98 S-98 O-98 N-98 D-98 J-99 F-99 M-99 A-99 M-99

Current State

POSITION ANALYSIS

1969

19841975

1970

1989

Stage simulated by a model

95%

50%

25%

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

Questions?

climate: outlook and operational planning jayantha obeysekera (’obey’), ph.d.,p.e.,d.wre...

Documents

wet season dry season

nio roller coasterel

normal rainfall

niosouthern oscillation

dry season monthsla

year cycleel nio

lake okeechobee water

week climate