Lesson 1: Introducing the Lesson 1: Introducing the Enhanced Fujita ScaleEnhanced Fujita Scale

Lesson 1: Introducing the Lesson 1: Introducing the Enhanced Fujita ScaleEnhanced Fujita Scale

Dan McCarthy ( NWS SPC)Dan McCarthy ( NWS SPC)

and and

Jim LaDue (NWS WDTB)Jim LaDue (NWS WDTB)

Goal and Scope of TrainingGoal and Scope of TrainingGoal and Scope of TrainingGoal and Scope of Training

• The Goal of this Training is to effectively integrate The Goal of this Training is to effectively integrate the EF-Scale into the post storm damage the EF-Scale into the post storm damage assessment.assessment.

• Two lessons, each followed by a quizTwo lessons, each followed by a quiz

– Comparison of the EF and F-ScaleComparison of the EF and F-Scale

– Using the EF-Scale to estimate tornado strengthUsing the EF-Scale to estimate tornado strength

MotivationMotivationMotivationMotivation

• EF-Scale to be used by the NWS starting 01 Feb, EF-Scale to be used by the NWS starting 01 Feb, 20072007

• More complex than F-ScaleMore complex than F-Scale

Lesson 1: Learning ObjectivesLesson 1: Learning ObjectivesLesson 1: Learning ObjectivesLesson 1: Learning Objectives

1.1. Understand why the EF-Scale was created Understand why the EF-Scale was created

2.2. Identify the methodology in creating the EF-Scale. Identify the methodology in creating the EF-Scale.

3.3. Understand the structure of the EF-ScaleUnderstand the structure of the EF-Scale

4.4. Identify differences between the EF- and F-ScaleIdentify differences between the EF- and F-Scale

5.5. Understand the strengths of the EF-ScaleUnderstand the strengths of the EF-Scale

6.6. Understand the limitations of the EF-ScaleUnderstand the limitations of the EF-Scale

Performance ObjectivePerformance ObjectivePerformance ObjectivePerformance Objective

• Apply the strengths and limitations of the EF-Scale Apply the strengths and limitations of the EF-Scale when rating damage produced by a tornadowhen rating damage produced by a tornado

Why the EF-Scale was createdWhy the EF-Scale was createdWhy the EF-Scale was createdWhy the EF-Scale was created

• Need more Need more damage damage indicatorsindicators

• recalibrate windsrecalibrate winds associated with F-scale associated with F-scale ratingsratings

• better better correlate wind correlate wind and ratingand rating

• account for account for construction construction variabilityvariability

• Flexibility, Extensibility, Flexibility, Extensibility, ExpandabilityExpandability

Evidence indicates a well Evidence indicates a well constructed house can be blown constructed house can be blown away by winds much less than away by winds much less than 260 mph 260 mph ((Phan and Simiu,2003)..

Objectives: 1, Why the EF-Scale?

The framed house is one of only The framed house is one of only a few F-scale damage a few F-scale damage indicators.indicators.

EF-Scale history: Steering CommitteeEF-Scale history: Steering CommitteeEF-Scale history: Steering CommitteeEF-Scale history: Steering Committee

Organize a Steering Committee (2001)

Jim McDonald - TTUJoe Schaefer - SPC

Brian Smith, NWS OAX

Michael Riley - NIST

Objectives: 2, Methodology

Kishor Mehta -TTU

Don Burgess – NSSL

The Steering Committee Organizes a ForumThe Steering Committee Organizes a ForumThe Steering Committee Organizes a ForumThe Steering Committee Organizes a Forum

• Led by Wind Science Led by Wind Science and Engineering and Engineering Center, Texas Tech Center, Texas Tech University, 7-8 March University, 7-8 March 20012001

• ObjectivesObjectives– Representative group of Representative group of

usersusers– ID key issuesID key issues– Make recommendationsMake recommendations– Develop a strategyDevelop a strategy

Objectives: 2, Methodology

The forum identifies EF-Scale development The forum identifies EF-Scale development strategiesstrategies

The forum identifies EF-Scale development The forum identifies EF-Scale development strategiesstrategies

• Identify additional Damage Indicators (DI)sIdentify additional Damage Indicators (DI)s• Correlate damage to wind speedCorrelate damage to wind speed

– Degrees of Damage (DOD) for each DIDegrees of Damage (DOD) for each DI

• Preserve the historical databasePreserve the historical database• Seek input from usersSeek input from users• Maximize usabilityMaximize usability

Objectives: 2, Methodology

EF-Scale Damage Indicators (DIs)EF-Scale Damage Indicators (DIs)EF-Scale Damage Indicators (DIs)EF-Scale Damage Indicators (DIs)

• 28 DIs were identified by the Steering Committee28 DIs were identified by the Steering Committee• DIs and DODs can be added or modifiedDIs and DODs can be added or modified• Each DI has several Degrees of Damage (DOD) Each DI has several Degrees of Damage (DOD)

Objectives: 2, methodology; 3, EF-Scale structure

Framed house Single wide mobile home Small Retail Building

28 Damage Indicators28 Damage Indicators28 Damage Indicators28 Damage Indicators

Objectives: 3, EF-Scale structure

Residences

Commercial/retail structures

Schools

Professional buildings

Metal buildings/canopies

Towers/poles

Vegetation

DOD Damage Description EXP LB UB

1 Threshold of visible damage ? ? ?

2 Loss of roof covering material (<20%), gutters and/or awning; loss of vinyl or metal siding

3 Broken glass in doors and windows

4 Uplift of roof deck and loss of significant roof covering material (>20%); collapse of chimney; garage doors collapse inward or outward; failure of porch or carport

5 Entire house shifts off foundation

6 Large sections of roof structure removed; most walls remain standing

7 exterior walls collapsed

8 Most walls collapsed except small interior rooms.

9 All walls collapsed

10 Destruction of engineered and/or well constructed residence; slab swept clean

Degrees of DamageDegrees of DamageDegrees of DamageDegrees of Damage

DOD for a Framed House, FR12 or DOD2

Objectives: 2, methodology; 3, EF-Scale structure

Reason behind an upper and lower bound Reason behind an upper and lower bound wind speedwind speed

Reason behind an upper and lower bound Reason behind an upper and lower bound wind speedwind speed

EXP: Design exhibits typical

construction

One, Two Family House

0

50

100

150

200

250

1 2 3 4 5 6 7 8 9 10

DOD

WIn

d S

peed (m

ph)

EXP

LB

UB

Win

d S

pee

d (

mp

h)

Objectives: 2, methodology; 3, EF-Scale structure

Reason behind an upper and lower bound Reason behind an upper and lower bound wind speed (contd)wind speed (contd)

Reason behind an upper and lower bound Reason behind an upper and lower bound wind speed (contd)wind speed (contd)

EXP: Design exhibits typical

construction

UB: Design exceeds codes for typical US home,

better than average load path.

LB: Design fails to meet US building

codes, poor maintenance

and/or load path

One, Two Family House

0

50

100

150

200

250

1 2 3 4 5 6 7 8 9 10

DOD

WIn

d S

peed (m

ph)

EXP

LB

UB

Win

d S

pee

d (

mp

h)

Objectives: 2, methodology; 3, EF-Scale structure

How the winds were derived for each DODHow the winds were derived for each DODHow the winds were derived for each DODHow the winds were derived for each DOD

• Possible CandidatesPossible Candidates– Structural analysis to determine resistance and Structural analysis to determine resistance and

theoretical failure modestheoretical failure modes– Simulation of tornado winds to produce structural

damage – Expert Elicitation

• Chosen method?– Expert Elicitation

Objectives: 2, EF-Scale methodology

Chosen Experts:Greg Forbes – Meteorologist, TWCDon Burgess – Meteorologist, NSSLDoug Smith – Engineer, TTUTim Reinhold – Engineer, Clemson UniversityTom Smith – Architect, ConsultantTim Marshall – Meteorologist/Engineer, Haag Engineers

Derive Wind Speeds by Expert Elicitation Derive Wind Speeds by Expert Elicitation Derive Wind Speeds by Expert Elicitation Derive Wind Speeds by Expert Elicitation

Objectives: 2, EF-Scale methodology

Describe the DIs and

DODs and present to

experts

Train the experts in elicitation process

Experts individually

estimate wind speeds for each

DOD

Mehta and McDonald analyze results and

present to experts for review

Experts revise their wind speeds

Iterate again

Present final estimates to

forum for review

Degrees of DamageDegrees of DamageDegrees of DamageDegrees of Damage

DOD Damage Description EXP LB UB

1 Threshold of visible damage 63 53 80

2 Loss of roof covering material (<20%), gutters and/or awning; loss of vinyl or metal siding 79 63 97

3 Broken glass in doors and windows 96 79 114

4 Uplift of roof deck and loss of significant roof covering material (>20%); collapse of chimney; garage doors collapse inward or outward; failure of porch or carport

97 81 116

5 Entire house shifts off foundation 121 103 141

6 Large sections of roof structure removed; most walls remain standing 122 104 142

7 exterior walls collapsed 132 113 153

8 Most walls collapsed except small interior rooms. 152 127 178

9 All walls collapsed 170 142 198

10 Destruction of engineered and/or well constructed residence; slab swept clean 200 162 220

Objectives: 3, EF-Scale structure

Example DODs for a Framed House DI (FR12 or DI2)

Note some consecutive DODs have larger overlap than others

DOD Damage Description EXP LB UB

1 Threshold of visible damage 63 53 80

2 Loss of roof covering material (<20%), gutters and/or awning; loss of vinyl or metal siding 79 63 97

3 Broken glass in doors and windows 96 79 114

4 Uplift of roof deck and loss of significant roof covering material (>20%); collapse of chimney; garage doors collapse inward or outward; failure of porch or carport

97 81 116

5 Entire house shifts off foundation 121 103 141

6 Large sections of roof structure removed; most walls remain standing 122 104 142

7 exterior walls collapsed 132 113 153

8 Most walls collapsed except small interior rooms. 152 127 178

9 All walls collapsed 170 142 198

10 Destruction of engineered and/or well constructed residence; slab swept clean 200 162 220

Degrees of DamageDegrees of DamageDegrees of DamageDegrees of Damage

DOD Damage Description EXP LB UB

1 Threshold of visible damage 63 53 80

2 Loss of roof covering material (<20%), gutters and/or awning; loss of vinyl or metal siding 79 63 97

3 Broken glass in doors and windows 96 79 114

4 Uplift of roof deck and loss of significant roof covering material (>20%); collapse of chimney; garage doors collapse inward or outward; failure of porch or carport

97 81 116

5 Entire house shifts off foundation 121 103 141

6 Large sections of roof structure removed; most walls remain standing 122 104 142

7 exterior walls collapsed 132 113 153

8 Most walls collapsed except small interior rooms. 152 127 178

9 All walls collapsed 170 142 198

10 Destruction of engineered and/or well constructed residence; slab swept clean 200 162 220

Example DODs for a Framed House DI (FR12 or DI2)

Note some consecutive DODs have larger overlap than others

One, Two Family House

0

50

100

150

200

250

1 2 3 4 5 6 7 8 9 10

DOD

WIn

d S

peed (m

ph)

EXP

LB

UB

Win

d S

pee

d (

mp

h)

Objectives: 2, methodology; 3, EF-Scale structure

Relating the F-scale with the EF-ScaleRelating the F-scale with the EF-ScaleRelating the F-scale with the EF-ScaleRelating the F-scale with the EF-Scale

• Need of historical Need of historical continuitycontinuity

• 22ndnd set of experts set of experts assigned F-scale assigned F-scale ratings to the same ratings to the same damage damage descriptionsdescriptions

• Median F-scale Median F-scale wind speeds wind speeds compared to that of compared to that of expected EF-Scale expected EF-Scale wind speedswind speeds

Objectives: 2, methodology; 4, EF vs F-Scale

The F-Scale wind speed was converted from the fastest ¼ mi to a 3 sec gust.

Bill Bunting – NWSFO – Fort Worth, TexasBrian Peters – NWSFO – Calera, AlabamaJohn Ogren – NWSFO – Indianapolis, IndianaDennis Hull – NWSFO – Pendleton, OregonTom Matheson – NWSFO – Wilmington, North CarolinaBrian Smith – NWSFO – Valley, Nebraska

Y = 0.6246x + 36.393R2 = 0.9118

F5 to EF5 threshold wind speed

F-Scale Converted to EF-Scale F-Scale Converted to EF-Scale

F ScaleF Scale Wind SpeedWind Speed EF-ScaleEF-Scale Wind SpeedWind Speed

F0F0 45-7845-78 EF0EF0 65-8565-85

F1F1 79-11779-117 EF1EF1 86-10986-109

F2F2 118-161118-161 EF2EF2 110-137110-137

F3F3 162-209162-209 EF3EF3 138-167138-167

F4F4 210-261210-261 EF4EF4 168-199168-199

F5F5 262-317262-317 EF5EF5 200-234200-234

Wind speeds in mph, 3-second gust

Objectives: 3, EF-Scale structure; 4, EF vs F-Scale

DOD to Wind Speed to EF-ScaleDOD to Wind Speed to EF-Scale

EF-Scale CategoriesEF-Scale Categories Wind Speed RangesWind Speed Ranges

EF0EF0 65-8565-85

EF1EF1 86-11086-110

EF2EF2 111-135111-135

EF3EF3 136-165136-165

EF4EF4 166-200166-200

EF5EF5 >200>200

Objectives: 3, EF-Scale structure

Wind speeds in mph, 3-second gust

Comparing Beaufort, F, and Mach ScalesComparing Beaufort, F, and Mach ScalesComparing Beaufort, F, and Mach ScalesComparing Beaufort, F, and Mach Scales

1 2 3 4 5 6 7 8 9 10 11 120Beaufort Scale

1 2 3 4 5 6 7 8 90 10 11 12Fujita Scale

0.6 1.0

Mach Scale

B1 B3B5

B7B9

B11

F0F1

F2

F3

F4

F5

F12M1.0

M0.6

M0.7

M0.8

B17

Beaufort: V = 1.870B3/2 mph F – scale: V = 14.1(F+2)3/2 mphMach scale: V = (742 +1.3)M mph

These scales have wind speed defined first, impacts/damage were assigned to wind speeds.

Objectives: 3, EF-Scale structure; 4, EF vs F-Scale

Comparing F and EF-ScalesComparing F and EF-ScalesComparing F and EF-ScalesComparing F and EF-Scales

1 2 3 4 5 6 7 8 9 10 11 120Beaufort Scale

1 2 3 4 5 6 7 8 90 10 11 12Fujita Scale

0.6 1.0

Mach Scale

B1 B3B5

B7B9

B11

F0F1

F2

F3

F4

F5

F12M1.0

M0.6

M0.7

M0.8

B17

EF0EF1

EF2EF3

EF4

EF5

0 1 2 3 4 5

EF-Scale

The EF-Scale is a damage scale: speeds were estimated from the damage

Objectives: 3, EF-Scale structure; 4, EF vs F-Scale

DOD to Wind Speed to EF-Scale questionDOD to Wind Speed to EF-Scale questionDOD to Wind Speed to EF-Scale questionDOD to Wind Speed to EF-Scale questionDOD Damage Description – Framed House EXP LB UB

1 Threshold of visible damage 63 53 80

2 Loss of roof covering material (<20%), gutters and/or awning; loss of vinyl or metal siding

79 63 97

3 Broken glass in doors and windows 96 79 114

4 Uplift of roof deck and loss of significant roof covering material (>20%); collapse of chimney; garage doors collapse inward or outward; failure of porch or carport

97 81 116

5 Entire house shifts off foundation 121 103 141

6 Large sections of roof structure removed; most walls remain standing 122 104 142

7 exterior walls collapsed 132 113 153

8 Most walls collapsed except small interior rooms. 152 127 178

9 All walls collapsed 170 142 198

10 Destruction of engineered and/or well constructed residence; slab swept clean

200 162 220

Objectives: 3, EF-Scale structure

Quiz: What DOD best corresponds with this damage?

DOD to Wind Speed to EF-Scale reviewDOD to Wind Speed to EF-Scale reviewDOD to Wind Speed to EF-Scale reviewDOD to Wind Speed to EF-Scale reviewDOD Damage Description – Framed House EXP LB UB

1 Threshold of visible damage 63 53 80

2 Loss of roof covering material (<20%), gutters and/or awning; loss of vinyl or metal siding

79 63 97

3 Broken glass in doors and windows 96 79 114

4 Uplift of roof deck and loss of significant roof covering material (>20%); collapse of chimney; garage doors collapse inward or outward; failure of porch or carport

97 81 116

5 Entire house shifts off foundation 121 103 141

6 Large sections of roof structure removed; most walls remain standing 122 104 142

7 exterior walls collapsed 132 113 153

8 Most walls collapsed except small interior rooms. 152 127 178

9 All walls collapsed 170 142 198

10 Destruction of engineered and/or well constructed residence; slab swept clean

200 162 220

Objectives: 3, EF-Scale structure

Expected wind 97 mph

EF-Scale answerEF-Scale answer

EF-Scale CategoriesEF-Scale Categories Wind Speed RangesWind Speed Ranges

EF0EF0 65-8565-85

EF1EF1 86-11086-110

EF2EF2 111-135111-135

EF3EF3 136-165136-165

EF4EF4 166-200166-200

EF5EF5 >200>200

Wind Speed in mph, 3-Second gust

Objectives: 3, EF-Scale structure

Strengths of EF-ScaleStrengths of EF-ScaleStrengths of EF-ScaleStrengths of EF-Scale

• EF-ScaleEF-Scale– 28 DIs28 DIs

– Accounts for differences of Accounts for differences of structural integrity within a DIstructural integrity within a DI

– Wind speeds determined from Wind speeds determined from damagedamage

– Continuity from the F-scale Continuity from the F-scale

– Expandibility, Flexibility, Expandibility, Flexibility, ExtensibilityExtensibility

• F ScaleF Scale– Only a Couple DIsOnly a Couple DIs

– No accounting for differences of No accounting for differences of structural integrity within a DIstructural integrity within a DI

– Wind speeds not derived from Wind speeds not derived from damagedamage

Objectives: 5, EF-Scale strengths

EF-Scale limitationsEF-Scale limitationsEF-Scale limitationsEF-Scale limitations

• Change in scale may introduce artifacts into the Change in scale may introduce artifacts into the historical recordhistorical record

• Complicated Complicated • Wind speeds subject to change for each ratingWind speeds subject to change for each rating• No function relating wind speed to ratingNo function relating wind speed to rating• Debate continues about wind speed assignmentsDebate continues about wind speed assignments

Objectives: 6, EF-Scale limitations

Summary: Lesson 1Summary: Lesson 1Summary: Lesson 1Summary: Lesson 1

• EF-Scale created to provide more DIs, more EF-Scale created to provide more DIs, more realistic wind speedsrealistic wind speeds

• EF-Scale winds were estimated using expert EF-Scale winds were estimated using expert elicitationelicitation

• EF-Scale contains 28 DIs, each with several DODs EF-Scale contains 28 DIs, each with several DODs ranging from first damage to destruction or if the ranging from first damage to destruction or if the estimated wind speeds correspond to an EF 5 estimated wind speeds correspond to an EF 5 rating.rating.

• EF-Scale winds significantly lower than F-scale for EF-Scale winds significantly lower than F-scale for EF (F3) and higherEF (F3) and higher

• EF-Scale is complicated requiring a longer time for EF-Scale is complicated requiring a longer time for familiarizationfamiliarization

Objectives: 1-6

References and suggested readingReferences and suggested readingReferences and suggested readingReferences and suggested reading

McDonald, J.R. and K.C. Mehta, 2001: Summary report of the Fujita Scale forum. Wind Science and Engineering, Texas Tech University, Lubbock, TX, 36 pp.

Phan, L.T. and E. Simiu, 1998: The Fujita tornado intensity scale: a critique based on observations of the Jarrell tornado of May 27, 1997. NIST Tech. Note 1426, U.S. Department of Commerce, Gaithersburg, MD, 20 pp.

SSHAC, 1997: Recommendations for probabilistic seismic hazard analysis: guidelines on uncertainty and use of experts, NUREG/CR6372, UCRL-ID-122160, Vol. I, Lawrence Livermore National Laboratory, Livermore, CA, 131 pp.

Suggested reading: A Recommendation for the Enhanced Fujita Scale: http://

www.spc.noaa.gov/efscale/

In Lesson 2In Lesson 2In Lesson 2In Lesson 2

• Lesson 2 provides you a chance to use the EF-Lesson 2 provides you a chance to use the EF-Scale on some damage tracksScale on some damage tracks

ContactsContactsContactsContacts

• If you have any questions about this lesson, contactIf you have any questions about this lesson, contact– Jim LaDue, Jim LaDue, James.G.LaDue@noaa.govJames.G.LaDue@noaa.gov– Dan McCarthy, Daniel.McCarthy@noaa.govDan McCarthy, Daniel.McCarthy@noaa.gov