Severe Thunderstorms and Tornadoes: Predicting the Unpredictable (Kelvin Droegemeier, Ph.D.)

8/7/2019 Severe Thunderstorms and Tornadoes: Predicting the Unpredictable (Kelvin Droegemeier, Ph.D.)

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Kelvin K. DroegemeierSchool of Meteorology

Center for Analysis and Prediction of StormsUniversity of Oklahoma

National Press Foundation Program Understanding ViolentWeather26 October 2005

Advances in theAdvances in the

Observation andObservation andComputer Prediction ofComputer Prediction of

Severe StormsSevere Storms


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Copyright 2003 WGN-TV

Everyone is Familiar With ThisEveryone is Familiar With This

Person!!Person!!


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Copyright 2003 WGN-TV

Computer ModelsComputer Models are the Primary Sourceare the Primary Source

of Information for All Weather Forecastsof Information for All Weather Forecasts


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Numerical WeatherNumer ca Weat er

PredictionPrediction

The use of computer modelsThe use of computer models

of the atmosphere toof the atmosphere topredict

predict the weather given athe weather given a

set of current observationsset of current observations


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According to WebsterAccording to Webster

s predictpredict: To state, tell about, or: To state, tell about, or

make known in advance, especiallymake known in advance, especially

on the basis of special knowledge.on the basis of special knowledge.


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MeteorologistsMeteorologists

s predictpredict: To state, tell about, or: To state, tell about, or

make known in advance, trying notmake known in advance, trying not

to lie and always keeping the cointo lie and always keeping the coinconcealed from curious onlookers.concealed from curious onlookers.


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The Prediction ProcessThe Prediction Process

Analyze ResultsAnalyze Results

Co

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areandV

erify

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area

ndVerify

Observe the AtmosphereObserve the Atmosphere

Identify and ApplyIdentify and Apply

Physical LawsPhysical Laws

Create a MathematicalCreate a Mathematical

ModelModel

Create and Run aCreate and Run a

Computer ModelComputer Model


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Co

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ModelModel




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Upper-AirUpper-Air

BalloonsBalloons

SatellitesSatellites

NEXRADNEXRAD

DopplerDoppler

RadarRadar

Commercial AircraftCommercial Aircraft

AutomatedAutomated

SurfaceSurfaceNetworksNetworks


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Co

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erify

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ndVerify Identify and ApplyIdentify and Apply



ModelModel





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LawsLaws

F=ma


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erify

Co

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ModelModel







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Create a Mathematical ModelCreate a Mathematical Model


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erify

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Verify







ModelModel


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Create Computer ModelCreate Computer Model


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Create Computer ModelCreate Computer Model


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s Solve highly nonlinear partial differential equationsSolve highly nonlinear partial differential equationss East/West WindEast/West Winds North/South WindNorth/South Winds Vertical WindVertical Winds TemperatureTemperatures Water VaporWater Vapors Cloud WaterCloud Waters Precipitating WaterPrecipitating Waters

Cloud IceCloud Ices GraupelGraupels HailHails Surface TemperatureSurface Temperatures Surface MoistureSurface Moistures Soil TemperatureSoil Temperatures Soil MoistureSoil Moistures Sub-Grid TurbulenceSub-Grid Turbulence

Run the Computer ModelRun the Computer Model


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s Over the course of a single forecast, the computerOver the course of a single forecast, the computer

model solves billions ofmodel solves billions of

equationsequations

s

Requires the fastestRequires the fastestsupercomputers in thesupercomputers in the

world -- capable ofworld -- capable of

performing trillions ofperforming trillions of

calculationscalculations

each secondeach second

Run the Computer ModelRun the Computer Model


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s Finer resolution allows the model to captureFiner resolution allows the model to capture

more detailmore detail

s Requires more computer powerRequires more computer power doubling the number of grid boxes in 3-D increases thedoubling the number of grid boxes in 3-D increases the

computer requirements by a factor of 16!computer requirements by a factor of 16!

More Power!!!More Power!!!


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ModelModel




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Results/Compare/VerifyResults/Compare/Verify


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In the Beginning ENIACIn the Beginning ENIAC


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ENIAC Versus TodayENIAC Versus Today

s Weighed 30 tonsWeighed 30 tons

s Had 18,000 vacuum tubes, 1,500Had 18,000 vacuum tubes, 1,500

relays thousands of resistors,relays thousands of resistors,

capacitors, inductorscapacitors, inductors

s Peak speed of 5000 adds/second andPeak speed of 5000 adds/second and

300 multiplies/sec300 multiplies/secs A 1.2 GHz Pentium IV processor isA 1.2 GHz Pentium IV processor is

500,000 times faster than the ENIAC500,000 times faster than the ENIAC

s A desktop PC with 1 Gbyte of RAMA desktop PC with 1 Gbyte of RAM

can store 5 million times as muchcan store 5 million times as muchdata as the ENIACdata as the ENIAC


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1950: The First Computer Weather1950: The First Computer Weather

Forecast ModelForecast Model

450 Miles


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Todays ModelsTodays Models

A T i l F t F T d A T i l F t F T d


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A Typical Forecast From TodaysA Typical Forecast From Todays

ModelsModels

W at auses t e Ma ora auses e a or


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W at auses t e Ma ora auses e a orProblems?Problems?


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Model?Model?

This Thunderstorm

Falls Through the Cracks


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Model?Model?


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A Foundational QuestionA Foundational Question

Can computer forecastCan computer forecast

technology. . .technology. . .

. . . explicitly predict this. . . explicitly predict this

type of weather?type of weather?

Would This Capability BeWould This Capability Be


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Would This Capability BeWould This Capability Be

Useful?Useful?

s Intense local weather causes economic losses in the US that averageIntense local weather causes economic losses in the US that average$300 M$300 Mper weekper week

s Over 30% of the $10 trillion US economy is impacted each yearOver 30% of the $10 trillion US economy is impacted each year

s Commercial aviation losesCommercial aviation loses $1-2 B per year$1-2 B per year due to diversions, delays,due to diversions, delays,and cancellations (one diverted flight costs $150K)and cancellations (one diverted flight costs $150K)

s Agriculture losses exceedAgriculture losses exceed $10 B/year$10 B/year


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Dutton (2002)Dutton (2002)


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Dutton (2002)Dutton (2002)


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Actual Losses Extreme EventsActual Losses Extreme Events

Pielke and Carbone (2002)Pielke and Carbone (2002)


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s Cargo shippingCargo shipping

Most expeditious route can save $40,000 per voyage thousands of ships travel continuously!Most expeditious route can save $40,000 per voyage thousands of ships travel continuously!

ExamplesExamples

s High temperature and humidity can cause grain to germinate in cargo holdsHigh temperature and humidity can cause grain to germinate in cargo holds

s Ships affected differently by wavelength of ocean swellsShips affected differently by wavelength of ocean swells

s Commercial aviationCommercial aviation

Single diversion averages $10,000 per domestic flightSingle diversion averages $10,000 per domestic flight

Not unusual for one carrier to have 70 diversions at a hub for a single weather event (1-2 hours)Not unusual for one carrier to have 70 diversions at a hub for a single weather event (1-2 hours)

Cost is $700,000 per eventCost is $700,000 per event

Industry loses $1-2 B per year due to weatherIndustry loses $1-2 B per year due to weather

Specific ExamplesSpecific Examples

Source: Weathernews, Inc.Source: Weathernews, Inc.


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About 50% of the loss is deemed preventable with better forecasts!


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s 876876 deaths annually due to severedeaths annually due to severeweatherweather

s 7000+7000+ weather-related traffic fatalitiesweather-related traffic fatalities

s 450,000450,000 weather-related traffic injuriesweather-related traffic injuries

LifeLife


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TypesTypesGlobal(2 weeks)


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Continental

(few days)


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Continental

(few days)

Special


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Continental

(few days)

Special

Operational


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Continental

(few days)

Regional

(day)

Local

(few hours)

Special

Experimental


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Increasin

gSki l

l

Trends in Large-Scale Forecast SkillTrends in Large-Scale Forecast Skill


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10 km 1 km

Crossing the DivideCrossing the Divide

s The next quantum leap in NWPThe next quantum leap in NWPwill come when we startwill come when we startresolving explicitly the mostresolving explicitly the most

energetic weather features,energetic weather features,e.g., individual convectivee.g., individual convectivestorms in 3-Dstorms in 3-D

s

For global models, theFor global models, thepredictability increases for allpredictability increases for allresolvable scales as theresolvable scales as thespatial resolution increasesspatial resolution increases The improvement isThe improvement is boundedbounded

Going finer than a few 10s of kmGoing finer than a few 10s of kmin grid spacing gives little payoffin grid spacing gives little payoff

60 km 30 km

30 km 10 km

Importance of Finer Grid Spacing in Models


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Importance of Finer Grid Spacing in Models

Courtesy NCAR

512 km


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256 km


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128 km


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64 km


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32 km


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8 km


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Where Are We Today?Where Are We Today?

s Tremendous advances are being made in the computer-based predictionTremendous advances are being made in the computer-based predictionof high-impact local weather, such asof high-impact local weather, such as thunderstormsthunderstorms, owing to, owing to

Increases in computer power and networking capacityIncreases in computer power and networking capacity

Affordability of computersAffordability of computers

Availability of fine-scale observations (NEXRAD Doppler radar)Availability of fine-scale observations (NEXRAD Doppler radar)

Improved understanding of the atmosphereImproved understanding of the atmosphere

Societal need, especially that of weather impacted industries (aviation, energy,Societal need, especially that of weather impacted industries (aviation, energy,

recreation, defense)recreation, defense)


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Example : March 28, 2000 FortExample : March 28, 2000 Fort

Worth Tornadic StormsWorth Tornadic Storms


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Tornado

NoNo Explicit EvidenceExp

licit Evidence of Precipitation in Northof Precipitation in North


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o p c de cep o ec p a o op

TexasTexas

6 pm 7 pm 8 pm


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Radar

Hourly Radar Observations

(Fort Worth Shown by the Pink Star)

6 pm 7 pm 8 pm


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Radar

Com

puterFor

ecast

2 hr 3 hr 4 hr


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As a ForecasterAs a Forecaster

Worried AboutWorried About

This RealityThis Reality

7 pm


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As a ForecasterAs a Forecaster

Worried AboutWorried AboutThis RealityThis Reality

How MuchHow Much

Trust WouldTrust Would

You Place inYou Place inThis ModelThis Model

Forecast?Forecast?

3 hr

7 pm


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UncertaintyUncertainty

s We never know the complete state of theWe never know the complete state of theatmosphere everywhere, with perfect accuracyatmosphere everywhere, with perfect accuracy

s Small observation errors can grow with time in aSmall observation errors can grow with time in aforecast (chaos)forecast (chaos)

s Rather than run aRather than run a singlesingle forecast from one estimateforecast from one estimateof the current conditions, we runof the current conditions, we run severalseveral basedbasedupon equally plausible initial conditions to accountupon equally plausible initial conditions to accountfor observational uncertaintyfor observational uncertainty

s This is ensemble forecastingThis is ensemble forecasting


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Actual RadarActual Radar


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Forecast #1Forecast #1 Forecast #2Forecast #2

Forecast #3Forecast #3 Forecast #5Forecast #5Forecast #4Forecast #4

Actual RadarActual Radar

P b bili f I P i i i


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Probability of Intense PrecipitationProbability of Intense Precipitation

Model Forecast Radar Observations


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MUCH MORE Computing Power isMUCH MORE Computing Power is

Required!!Required!!Forecast #1Forecast #1

Forecast #50Forecast #50



Recent Real Time Experimental ForecastsRecent Real Time Experimental Forecasts


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pp

Run by OU for the National WeatherRun by OU for the National Weather

ServiceService

Actual Radar Observations

Recent Real Time Experimental ForecastsRecent Real Time Experimental Forecasts


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pp

Run by OU for the National WeatherRun by OU for the National Weather

ServiceService

24 Hour Forecast Actual Radar Observations


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A Foundational QuestionA Foundational Question

Can computer forecastCan computer forecast

technology. . .technology. . .

. . . explicitly predict this. . . explicitly predict this

type of weather?type of weather?

The Answer Appears to be Yes, But NewMethodologies May Be Needed

Tornadoes Requires Fine-ScaleTornadoes Requires Fine-Scale


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qq

ObservationsObservations

NEXRAD Doppler Radar Network

yUSUS


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USUS

NEXRAD Doppler Radar Network

The Limitations of NEXRADThe Limitations of NEXRAD


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#2. Earths curvature prevents 72% of the atmosphere below 1#2. Earths curvature prevents 72% of the atmosphere below 1

km from being observedkm from being observed

#1. Operates largely independent#1. Operates largely independent

of the prevailing weather conditionsof the prevailing weather conditions

#3. Operates entirely independent from#3. Operates entirely independent from

the models and algorithms that use itsthe models and algorithms that use its

datadata

The Limitations of NEXRADThe Limitations of NEXRAD

The ConsequenceThe Consequence


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Source: NWS Office of Science and Technology

NEXRAD

NEXRAD

The ConsequenceThe Consequence

Research Center forResearch Center for


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Adaptive Sensing of theAdaptive Sensing of the

Atmosphere (CASA)Atmosphere (CASA)

s UMass/Amherst, OU, CSU, UPRMUMass/Amherst, OU, CSU, UPRMs Concept: inexpensive, phased array Doppler radars onConcept: inexpensive, phased array Doppler radars on

cell towers and buildingscell towers and buildings

s Dynamically adaptive dynamicDynamically adaptive dynamic sensing of multiplesensing of multipletargets while simultaneously meeting multiple end-usertargets while simultaneously meeting multiple end-user

needsneeds


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O SOkl h T t B d S i 2006


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Oklahoma Test Bed: Spring 2006Oklahoma Test Bed: Spring 2006


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The $1M Question: Will Numerical Models Ever Be Able to Predict Tornadoes?


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Schematic Diagram of a Supercell Storm (C. Doswell)


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Th F


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The FutureThe Future

s The National Weather Service will begin running models toThe National Weather Service will begin running models to explicitlyexplicitly

predictpredict thunderstormsthunderstormss Private companies willPrivate companies will

play a major role inplay a major role inproviding customizedproviding customizednumerical forecasts fornumerical forecasts forweather-sensitiveweather-sensitiveindustries, especiallyindustries, especially

energy and aviationenergy and aviation



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s

Human forecasters will continue toHuman forecasters will continue tobe essential, though with changingbe essential, though with changing

rolesroles

C f iC t t I f ti


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Contact InformationContact Information

Kelvin K. Droegemeier

University of Oklahoma

Sarkeys Energy Center, Suite 1110

100 East Boyd StreetNorman, OK 73019

Email: [email protected]

Phone: 405-325-0453

Fax: 405-325-7614Mobile: 405-413-7847

Documents

Severe Thunderstorms and Tornadoes: Predicting the Unpredictable (Kelvin Droegemeier, Ph.D.)