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Storm Based WarningsStorm Based Warnings

A New Direction in the A New Direction in the Warning ProcessWarning Process

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National Weather ServiceNational Weather Service

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OverviewOverview

Brief History of Storm Based (SB) Brief History of Storm Based (SB) WarningsWarningsImplementation Schedule Implementation Schedule SB Methodology SB Methodology ResourcesResourcesBenefits Benefits Challenges Challenges Summary Summary


Brief History Brief History

Sub County Information Added to NWS Short Sub County Information Added to NWS Short Duration Warnings in the late 1990sDuration Warnings in the late 1990s– ““Area of Maximum Impact” Defined by Sets of Area of Maximum Impact” Defined by Sets of

LAT/LON Point Pairs At Bottom of Text LAT/LON Point Pairs At Bottom of Text WarningsWarnings

– Polygon – Graphical Depiction of the LAT/LON Polygon – Graphical Depiction of the LAT/LON Point Pairs Point Pairs

– Short Duration WarningsShort Duration Warnings – Tornado, Severe – Tornado, Severe Thunderstorm, Flash Flood and Special Marine Thunderstorm, Flash Flood and Special Marine

Sub County Information Added to Follow Up Sub County Information Added to Follow Up Statements in 2002 Statements in 2002 – Allowed Forecasters to Update the “Area of Allowed Forecasters to Update the “Area of

Maximum Impact” Based on Current Conditions Maximum Impact” Based on Current Conditions The Warning Still Involved the Entire County!The Warning Still Involved the Entire County!


Brief History Part II Brief History Part II

Demonstration at 25 Forecast Offices in 2005 Demonstration at 25 Forecast Offices in 2005 – Reduction in total area warned - Reduction in total area warned - 73% 73% – Reduction in total number of towns warned Reduction in total number of towns warned

- - 70%70%NWS Senior Leadership Approves The NWS Senior Leadership Approves The Change to Storm Based Warnings in Change to Storm Based Warnings in December 2005 December 2005 NWS Meets With National Private Weather NWS Meets With National Private Weather Vendors in December 2006 to Discuss Vendors in December 2006 to Discuss Software Changes Required to Support The Software Changes Required to Support The Change to Storm Based Warnings Change to Storm Based Warnings


SB Approach EliminatesSB Approach EliminatesArea FalseArea FalseAlarmedAlarmed

SB False Alarm Area SB False Alarm Area ReductionReduction


SB False Alarm Area SB False Alarm Area ReductionReduction

County Based Warnings Storm Based Warnings


Value of reduced area Value of reduced area warnedwarned

Dr. Daniel S. Sutter*, Associate Professor of Economics, Dr. Daniel S. Sutter*, Associate Professor of Economics, University of Oklahoma estimates that…University of Oklahoma estimates that…

If the typical polygon warning was about 1/4 the size If the typical polygon warning was about 1/4 the size of the typical warned county, the value of reduced of the typical warned county, the value of reduced area under warnings would be almost area under warnings would be almost $50 million per $50 million per yearyear; ;

Reducing the area of the typical tornado warning to Reducing the area of the typical tornado warning to 1/41/4 of the current county size would produce about of the current county size would produce about the same increase in value of the warning as reducing the same increase in value of the warning as reducing the false alarm rate to the false alarm rate to zerozero. .

* Author of “eco-weather” articles in * Author of “eco-weather” articles in Weather and ForecastingWeather and Forecasting 2002 and 2005 2002 and 2005


SB Implementation SB Implementation

Implementation Date – October 1, Implementation Date – October 1, 20072007

Products Impacted Products Impacted – Tornado Warnings Tornado Warnings – Severe Thunderstorm Warnings Severe Thunderstorm Warnings – Flash Flood Warnings Flash Flood Warnings – Special Marine Warnings Special Marine Warnings – Severe Weather StatementsSevere Weather Statements– Flash Flood StatementsFlash Flood Statements– Marine Weather Statements Marine Weather Statements


SB Methodology SB Methodology Forecast Office Issues a Warning For A Portion of Forecast Office Issues a Warning For A Portion of County or Counties County or Counties – Warned Area Defined and Depicted By The Polygon Warned Area Defined and Depicted By The Polygon

(LAT/LON Point Pairs) (LAT/LON Point Pairs) – Portions of Counties Verbally Described by Compass Points Portions of Counties Verbally Described by Compass Points

(e.g. North, Northeast, East, Southwest, Central etc.)(e.g. North, Northeast, East, Southwest, Central etc.)

Forecast Office Updates a Warning Using a Follow Forecast Office Updates a Warning Using a Follow Statement Statement – Polygon Can Shrink In Area, But Not Expand Polygon Can Shrink In Area, But Not Expand

Forecast Office Cancels the Warning or Allows It to Forecast Office Cancels the Warning or Allows It to Expire When Conditions No Longer Meet Warning Expire When Conditions No Longer Meet Warning Criteria Criteria IMPORTANT – More Than One Warning Can Be IMPORTANT – More Than One Warning Can Be In Effect For One County at the Same Time!In Effect For One County at the Same Time!


SB Warnings – Outbreak SB Warnings – Outbreak Days Days


SB Warnings – A Closer SB Warnings – A Closer Look Look


SB Resources SB Resources

NWS RIDGE Radar Display NWS RIDGE Radar Display – Available on Every WFO Web Site Available on Every WFO Web Site

Private Weather Vendors Were Briefed In Private Weather Vendors Were Briefed In December 2006 December 2006

Weather Data, WSIWeather Data, WSIBarons, MeteorologixBarons, Meteorologix

Graphical displays via weather radios, cell Graphical displays via weather radios, cell phones, PDAs, etc.phones, PDAs, etc.


RIDGE Radar DisplayRIDGE Radar Display


SB Benefits SB Benefits Warnings Focused on Weather and Water Hazards Warnings Focused on Weather and Water Hazards – Warned Area Reduced on Average By 75%; Up to 97% Warned Area Reduced on Average By 75%; Up to 97%

Reduction in Western U.S. CountiesReduction in Western U.S. Counties– ““Blue Sky” Effect Reduced By Finer Resolution WarningsBlue Sky” Effect Reduced By Finer Resolution Warnings

Warnings Defined By GIS CoordinatesWarnings Defined By GIS Coordinates– Adaptable to Local Distribution Via Cell Phones, PDAs, etc. Adaptable to Local Distribution Via Cell Phones, PDAs, etc. – Improved Display Capabilities for Television, Internet Improved Display Capabilities for Television, Internet

Better Public ServiceBetter Public Service– Improved Information For Decision Makers – Emergency Improved Information For Decision Makers – Emergency

Managers Managers – More Accurate Depiction of Threat To U.S. Citizens More Accurate Depiction of Threat To U.S. Citizens – Warnings Are The Best Science and Technology Can Warnings Are The Best Science and Technology Can

Provide Provide


One WFOs Study (2004)One WFOs Study (2004)

In 2004, issued tornado warnings for counties that In 2004, issued tornado warnings for counties that covered:covered:– 31,990 square miles31,990 square miles– Included 494 individual townsIncluded 494 individual townsUtilizing the polygon approach, the polygons Utilizing the polygon approach, the polygons covered:covered:– 9,500 square miles9,500 square miles– Included 152 individual townsIncluded 152 individual townsIf the polygon approach were in place:If the polygon approach were in place: – Would have Would have reducedreduced our total warning area by our total warning area by

22,490 square miles22,490 square miles– Would have unnecessarily warned 242 Would have unnecessarily warned 242 fewerfewer towns towns– That's a That's a reduction of 70%!reduction of 70%!


SB Benefits – Use By SB Benefits – Use By PartnersPartners


SB Benefits – Demographic/Census SB Benefits – Demographic/Census Information Information


SB Challenges SB Challenges Legacy Dissemination Technology Is County Based Legacy Dissemination Technology Is County Based – NOAA Weather Radio NOAA Weather Radio – EAS Activation (FCC) EAS Activation (FCC) – Majority of Siren Systems (County/Local Government) Majority of Siren Systems (County/Local Government)

Multiple Warnings in One County Multiple Warnings in One County – Easy To Differentiate Graphically; Easy To Differentiate Graphically; Hard to Describe Verbally Hard to Describe Verbally

– VTEC Event Tracking Number Uniquely Defines Multiple VTEC Event Tracking Number Uniquely Defines Multiple

Warnings For Parsing Computer Programs Warnings For Parsing Computer Programs

Environmental Factors and Drawing Polygons Environmental Factors and Drawing Polygons – Right and Left Turning Supercells Right and Left Turning Supercells – Pulse Thunderstorms Pulse Thunderstorms – Basin Flooding Basin Flooding


Multiple Warnings in One Multiple Warnings in One County/ParishCounty/Parish

Issue for text, Issue for text, radio, TV crawlsradio, TV crawls

Add reference to Add reference to other valid other valid warningswarnings

Include counties Include counties with directional with directional delimiters?delimiters?

Summary severe Summary severe weather weather statements?statements?

Madison

Bond

Clinton

Fayette

Marion

St. Clair

Washington

Randolph

Perry

Jackson

Franklin

Jefferson

Williamson

TOR until 3:30PM

SVR until 3:45PM


SUMMARYSUMMARY

SB Warnings Start On October 1, 2007 SB Warnings Start On October 1, 2007 These Warnings Are Weather and Water These Warnings Are Weather and Water Specific and Use GIS Coordinates to Define Specific and Use GIS Coordinates to Define the Warned Area the Warned Area Resources Such As The NWS RIDGE Radar Resources Such As The NWS RIDGE Radar Display Are Available Now For Partners and Display Are Available Now For Partners and Customers Customers Challenges Remain Such as Current NOAA Challenges Remain Such as Current NOAA Weather Radio and EAS Activation Weather Radio and EAS Activation Technology Technology SB Warnings Provide Better Public Service SB Warnings Provide Better Public Service and Reflect The Cutting Edge of Meteorology and Reflect The Cutting Edge of Meteorology and Hydrology and Hydrology


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