gridded warnings the next generation of nws warning product?

11 July 2007 2nd Wkshp on Severe Wx Technology for NWS Warning Decision Making

Contributions:David AndraHarold BrooksDon BurgessCharles KerrJim LaDueMike MagsigKiel OrtegaKevin ScharfenbergTravis SmithGreg StumpfLou Wicker

Contributions:David AndraHarold BrooksDon BurgessCharles KerrJim LaDueMike MagsigKiel OrtegaKevin ScharfenbergTravis SmithGreg StumpfLou Wicker

Gridded Warnings

The next generation of NWS warning product?

Gridded Warnings

The next generation of NWS warning product?

HWT/EWP Participants:Brad GrantLes LemonDan MillerSteve NelsonPatrick BurkeLiz QuoetoneDave SharpSteve Zubrick

HWT/EWP Participants:Brad GrantLes LemonDan MillerSteve NelsonPatrick BurkeLiz QuoetoneDave SharpSteve Zubrick


IntroductionIntroduction

This idea and project are nascent.

This work must consider many intersecting disciplines:

Meteorology

Technology

Sociology

Human Factors

This idea and project are nascent.

This work must consider many intersecting disciplines:

Meteorology

Technology

Sociology

Human Factors


Recap from 1st WkshpRecap from 1st Wkshp

Warnings (forecasts) are for areasReports (events) are points

Probability of Detection (POD):points within polygons / total points

False Alarm Ratio (FAR):polygons without points / total polygons

Measures of skill (e.g., CSI) cannot be calculatedThese definitions are inconsistentNo measure of correct null forecastsWarning area sizes are inconsistentVerification really affects areas, not points

Warnings (forecasts) are for areasReports (events) are points

Probability of Detection (POD):points within polygons / total points

False Alarm Ratio (FAR):polygons without points / total polygons

Measures of skill (e.g., CSI) cannot be calculatedThese definitions are inconsistentNo measure of correct null forecastsWarning area sizes are inconsistentVerification really affects areas, not points


Storm versus CountyStorm versus County

NWS implementing “Storm-based Warnings” for FY08.

Characterizes the area to be threatened with (supposedly) no regard to geopolitical boundaries

But there are still issues

NWS implementing “Storm-based Warnings” for FY08.

Characterizes the area to be threatened with (supposedly) no regard to geopolitical boundaries

But there are still issues


Area-Based WarningShortcomings


Storm-based warnings are still area forecasts verified by point events.

The polygons are just “differently shaped”

The threat information for the polygon remains “monotonic”

Each location inside polygon is under exact same threat for the exact same time period

Each location inside (outside) polygon is given 100% (0%) certainty of event

Storm-based warnings are still area forecasts verified by point events.

The polygons are just “differently shaped”

The threat information for the polygon remains “monotonic”

Each location inside polygon is under exact same threat for the exact same time period

Each location inside (outside) polygon is given 100% (0%) certainty of event


VisionVision

Warnings and Reports are GRIDDED

Consistency between forecasts and events

Consistency with other forecast products

Allows for growth (added detail)

Can be aggregated to simpler formats

Warnings and Reports are GRIDDED

Consistency between forecasts and events

Consistency with other forecast products

Allows for growth (added detail)

Can be aggregated to simpler formats


OB8.1 WarnGen Limitations

OB8.1 WarnGen Limitations

Allow toggling individual counties off/on

Automatically clip small portions of counties within an area threshold setting

Not provide for situations when threats straddle adjacent CWAs

Not match the edges of adjacent warnings where there was manual or automated county clipping

Not provide a easily-identifiable preview of the actual polygon until the after the warning was transmitted

Allow toggling individual counties off/on

Automatically clip small portions of counties within an area threshold setting

Not provide for situations when threats straddle adjacent CWAs

Not match the edges of adjacent warnings where there was manual or automated county clipping

Not provide a easily-identifiable preview of the actual polygon until the after the warning was transmitted


Polygon SliversPolygon Slivers

This storm produced adamaging tornado that went nearly down the unwarned “sliver” that the arrow points to!


Was this really intended?Was this really intended?


Downstream WarningsDownstream Warnings

Very little overlap between adjacent warnings

Many times, a new polygon is issued only when storm is just about to exit the previous polygon.

This gives inconsistent lead time to all points within each polygon, with some points getting much less and sometimes zero lead time.

Very little overlap between adjacent warnings

Many times, a new polygon is issued only when storm is just about to exit the previous polygon.

This gives inconsistent lead time to all points within each polygon, with some points getting much less and sometimes zero lead time.


A

t=0


A B

t=0

No Warning for User BNo Warning for User B


A B

t=5



A B

t=10



A B

t=15



A B

t=20



A B

t=25



A B

t=30



A B

t=35



A B

t=40



A B

t=45



A B

t=50

< 5 min lead time for User B



A B

t=55






WarnGen has a motion estimator (“Drag Me To Storm”):

But, once any vertex in the swath polygon is changed, the storm motion and swath become decoupled

e.g., if swath is lengthened or shortened, it no longer matches the storm speed and warning time.

Forecaster has no control over initial swath area provided by WarnGen (point and line motion only)

Forecaster has no control over motion uncertainty values (speed and direction)

Therefore, the forecaster can only guess the result of these variables when adjusting the swath polygon

WarnGen has a motion estimator (“Drag Me To Storm”):

But, once any vertex in the swath polygon is changed, the storm motion and swath become decoupled

e.g., if swath is lengthened or shortened, it no longer matches the storm speed and warning time.

Forecaster has no control over initial swath area provided by WarnGen (point and line motion only)

Forecaster has no control over motion uncertainty values (speed and direction)

Therefore, the forecaster can only guess the result of these variables when adjusting the swath polygon


HypothesisHypothesis

Instead of the forecaster guessing at the swath…

…we propose that much more robust warning information can be derived if the forecaster instead determines

the initial threat area at time=0, along with the motion vector, and adds motion uncertainty information

Instead of the forecaster guessing at the swath…

…we propose that much more robust warning information can be derived if the forecaster instead determines

the initial threat area at time=0, along with the motion vector, and adds motion uncertainty information


Drivers for growthDrivers for growth

This information used to integrate a more accurate swath

Continuously advecting threat areas

Meaningful guidance on time of arrival and time of departure

Allows for the addition of forecaster uncertainty information (e.g., probabilities)

This information used to integrate a more accurate swath

Continuously advecting threat areas

Meaningful guidance on time of arrival and time of departure

Allows for the addition of forecaster uncertainty information (e.g., probabilities)


Deriving SwathDeriving Swath

time = 0

User defines:Initial Threat Area at time=0


time = -20

Use cursor to repositionthreat area

MethodMethod

User:Drag Me To Storm


time = 0, 15, 30, 45, 60

MethodMethod

Motion Vector Calculated


MethodMethod

Threat Area Advected


MethodMethod

User Defines:Motion Uncertainty

± 5 m s-1 ±15°


MethodMethod

Speed uncertainty stretches threat along motion vector

± 5 m s-1 ±15°


MethodMethod

Direction uncertainty stretches threat perpendicular to motion vector

± 5 m s-1 ±15°


MethodMethod

Integrated threat area across warning time provides swath


Swath propertiesSwath properties

Greater (lesser) motion uncertainty leads to wider (more narrow) swath

Larger (smaller) initial threat area leads to wider (more narrow) swath

Neither of these factors can be controlled in WarnGen.

Swaths are truly independent of geopolitical boundaries.

Greater (lesser) motion uncertainty leads to wider (more narrow) swath

Larger (smaller) initial threat area leads to wider (more narrow) swath

Neither of these factors can be controlled in WarnGen.

Swaths are truly independent of geopolitical boundaries.


Advecting threatAdvecting threat

As threat area advects downstream, the area affects different grid points at different times.

For each grid point in the warning, the intersection of the threat area over time provides information about

time of arrivaltime of departure

As threat area advects downstream, the area affects different grid points at different times.

For each grid point in the warning, the intersection of the threat area over time provides information about

time of arrivaltime of departure


x

t=0

A B

A B

1

0

TOA TOD

Warn?

Time

NOTE:No warning (yet)For User B

Advecting Threat AreaAdvecting Threat Area


xA

t=5

B

A B

1

0

TOA TOD TODTOA

Warn?

Time

NOTE:> 40 min lead timeFor User B



xA

t=10

B


A B

1

0

TOA TOD TODTOA

Warn?

Time


xA

t=15

B

A B

1

0

TOA TOD TODTOA

Warn?

Time



xA

t=20

B

A B

1

0

TOA TOD TODTOA

Warn?

Time



xA

t=25

B

A B

1

0

TOA TOD TODTOA

Warn?

Time



xA

t=30

B

A B

1

0

TOA TOD TODTOA

Warn?

Time



xA

t=35

B

A B

1

0

TOA TOD TODTOA

Warn?

Time

NOTE:Point A alreadyIn “all clear”



xA

t=40

B

A B

1

0

TOA TOD TODTOA

Warn?

Time




xA

t=35

B

A B

1

0

TOA TOD TODTOA

Warn?

Time




xA

t=50

B

A B

1

0

TOA TOD TODTOA

Warn?

Time




Threat TypeThreat Type

Each severe weather type can be depicted on separate grids

HailWindTornadoLightning

Threat subtypes could also be depictedHail sizeWind speedLightning Density

Each severe weather type can be depicted on separate grids

HailWindTornadoLightning

Threat subtypes could also be depictedHail sizeWind speedLightning Density


Redefining threat areas

Redefining threat areas

As an analog to the Severe Weather Statement (an update to an issued warning)…

Regularly redefine threat areas in time intervals (e.g., every 15 min), or when threat begins to deviate from the forecast

This is a continually evolving process

As an analog to the Severe Weather Statement (an update to an issued warning)…

Regularly redefine threat areas in time intervals (e.g., every 15 min), or when threat begins to deviate from the forecast

This is a continually evolving process


A Real CaseA Real Case

We won’t tell you where or when!We won’t tell you where or when!


How is grid produced?How is grid produced?

Isolate current threat area at time=0Isolate current threat area at time=0


How is grid produced?How is grid produced?

Input:Warning type

Hail Wind Tornado

Warning lengthMotion vector

speed direction

Motion uncertainty Speed Direction

Input:Warning type

Hail Wind Tornado

Warning lengthMotion vector

speed direction

Motion uncertainty Speed Direction


Result is warning swathResult is warning swath


WDSSII Rotation Tracks

Summary ofentire event


NOTE:Very little overlap in some warningsSome areas never warnedVery few polygons seem to depict the actual swath

NOTE:Very little overlap in some warningsSome areas never warnedVery few polygons seem to depict the actual swath

NWS Tornado Warnings



HWT GriddedTornado Warnings



ProbabilitiesProbabilities

This method allows for the inclusion of probabilistic information:

As threat area grows with time, the probability that a grid point will receive severe weather will naturally drop.

We allow the user to define their initial uncertainty, as well as forecasted uncertainty

The forecast probabilities are multiplied with the probabilities derived from motion uncertainty.

This method allows for the inclusion of probabilistic information:

As threat area grows with time, the probability that a grid point will receive severe weather will naturally drop.

We allow the user to define their initial uncertainty, as well as forecasted uncertainty

The forecast probabilities are multiplied with the probabilities derived from motion uncertainty.


Probabilistic SwathProbabilistic Swath

>50%>25%

>10%>0%

A B


Does this look familiar?Does this look familiar?


Probabilistic InfoProbabilistic Info

For each grid point in the warning, the intersection of the threat area over time provides time of arrival and time of departure information, and probabilities of the event.

For each grid point in the warning, the intersection of the threat area over time provides time of arrival and time of departure information, and probabilities of the event.

A B

1

0

Warn?

Time


Adding probabilitiesAdding probabilities

Input:Initial ProbabilityPeak ProbabilityTime of Peak ProbabilityDecay Method

By Time By Area Time and Area

Input:Initial ProbabilityPeak ProbabilityTime of Peak ProbabilityDecay Method

By Time By Area Time and Area


Result is probabilistic swath

Result is probabilistic swath


SociologySociology

FAQ: “Will the public understand probabilistic warnings?”

Answer:

The Public ≠


Answer:

The Public ≠

A monolithic mass with equal needs


SociologySociology


Answer:

The Public =


Answer:

The Public =

Spectrum of Warning Users with differing needs


SociologySociology

Risk = Hazard * ExposureRisk = Hazard * Exposure

e.g., Tornado, wind, hail, hazardous materials

How to account for this?


SociologySociology

The NWS cannot anticipate everyone’s exposure

The NWS can make hazard warnings more adaptable to those that do know their own exposure

Adaptive warnings allow users to set their threshold criteria

Adaptive warnings need to exploit digital media

The NWS cannot anticipate everyone’s exposure

The NWS can make hazard warnings more adaptable to those that do know their own exposure

Adaptive warnings allow users to set their threshold criteria

Adaptive warnings need to exploit digital media


How this gridded data can be used

How this gridded data can be used

Any high resolution grid (space and time) can be aggregated into simpler and simpler formats across all levels of sophistication

Even right down to the original county-based warnings (needed for NOAA All-Hazards Radio, some tv crawl software).

The more-deatiled information can allow users to adapt, and third-party vendors to provide better information to their clients.

GIS

Any high resolution grid (space and time) can be aggregated into simpler and simpler formats across all levels of sophistication

Even right down to the original county-based warnings (needed for NOAA All-Hazards Radio, some tv crawl software).

The more-deatiled information can allow users to adapt, and third-party vendors to provide better information to their clients.

GIS


Which counties get warned?

Which counties get warned?


But….which users get warned?

But….which users get warned?

C

BA

ED


Human FactorsHuman Factors

Tested concept within the HWT/EWP this spring with visiting WFO forecasters, WDTB trainers, and CIMMS/NSSL/MDL scientists.

Feedback on technological improvements

Feedback on workload management

For example, worked best with this team set-up:

Tech interface (per sector) Storm interrogation (per sector) Near-storm environment

Tested concept within the HWT/EWP this spring with visiting WFO forecasters, WDTB trainers, and CIMMS/NSSL/MDL scientists.

Feedback on technological improvements

Feedback on workload management

For example, worked best with this team set-up:

Tech interface (per sector) Storm interrogation (per sector) Near-storm environment


Science QuestionsScience Questions

How do we define the initial threat area?

What do these probabilities mean?

How do we calibrate the probabilities?

Storm-type classification study

How do we define the initial threat area?

What do these probabilities mean?

How do we calibrate the probabilities?

Storm-type classification study


Science QuestionsScience Questions

Verification of grids (see Brooks’ 1st Workshop talk)

Storm reports are still points “Splat”? High density verification (e.g., SHAVE) Probabilistic verification (e.g., radar)

Will need new metrics!

Verification of grids (see Brooks’ 1st Workshop talk)

Storm reports are still points “Splat”? High density verification (e.g., SHAVE) Probabilistic verification (e.g., radar)

Will need new metrics!


Future ConsiderationsFuture Considerations

This is an opportunity, not necessarily “the solution”

Next-generation warning tool

C*STAR proposal

Must be a multi-disciplinary effort

This is an opportunity, not necessarily “the solution”

Next-generation warning tool

C*STAR proposal

Must be a multi-disciplinary effort


Questions?Questions?

[email protected]

NWS Meteorological Development Laboratory

Decision Assistance Branch

[email protected]

NWS Meteorological Development Laboratory

Decision Assistance Branch


Bonus SlidesBonus Slides


Multiple ThreatsMultiple Threats

Can provide TOA and TOD for multiple threats affecting same areas (e.g., training storms)

Can provide TOA and TOD for multiple threats affecting same areas (e.g., training storms)

x x


“Open-ended” warnings“Open-ended” warnings

An “open-ended” warnings is one with a very long expiration time

Can eventually merge upscale to watch and convective outlook probabilities.

“Warn on Forecast” can help bridge the gap between these scales.

An “open-ended” warnings is one with a very long expiration time

Can eventually merge upscale to watch and convective outlook probabilities.

“Warn on Forecast” can help bridge the gap between these scales.

AB

1h 4h

gridded warnings the next generation of nws warning product?

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