SPC Convective Outlook Changes Changes in Category
Names/Definitions Bill Sammler Warning Coordination Meteorologist
National Weather Service, Wakefield VA http://weather.gov/akq
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Storm Prediction Center (SPC) Located in Norman, OK since 1997
Issues Outlooks for Thunderstorms/Severe Thunderstorms and Fire
Weather Issues All Tornado and Severe Tstm WATCHES nationwide
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Current SPC Outlooks 3 Tiers - SLGT, MDT and HIGH See Text Used
for Marginal Situations Increased Coverage and Higher Intensity
with MDT/HIGH
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Rationale for Proposed Changes Limitations of SEE TEXT and SLGT
SLGT, MDT, HIGH have been used for 40 years and have some
established understanding. Breakpoint thresholds for these
categories remain essentially unchanged Addition of ENH addresses
concern about SLGT (word meaning and probabilistic range)
Numbers/colors on legend will further aid interpretation Social
science informed SPC discussions on the change
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Day10%2%5%10%10% sig15%15% sig30%30% sig45%45% sig60%60% sig
Tor Wind Hail Day20%5%15%15% sig30%30% sig45%45% sig60%60% sig All
Svr Day30%5%15%15% sig30%30% sig45%45% sig All Svr Day4-815%30% All
Svr TSTMS SLGT MARGINAL ENHANCED MDT HIGH SPC Severe Weather
Outlook Probability-to-Categorical Description Tables (2014)
Increase risk categories to 5 levels for Day 1, Day 2, & Day 3
Outlooks Category 1 = MRGL Category 2 = SLGT Category 3 = ENH
Category 4 = MDT Category 5 = HIGH Day 1-3 Outlook Changes sig =
Significant Severe Tstms = Hail 2+ and/or Wind 65KT/75 MPH
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Increase risk categories to 5 levels for Day 1, Day 2, &
Day 3 Outlooks Replace See Text with Marginal for lowest risk
probabilities (Day 1 - Day 3) Day10%2%5%10%10% sig15%15% sig30%30%
sig45%45% sig60%60% sig Tor Wind Hail Day20%5%15%15% sig30%30%
sig45%45% sig60%60% sig All Svr Day30%5%15%15% sig30%30% sig45%45%
sig All Svr Day4-815%30% All Svr TSTMS SLGT MARGINAL ENHANCED MDT
HIGH SPC Severe Weather Outlook Probability-to-Categorical
Description Tables (2014) Day 1-3 Outlook Changes sig = Significant
Severe Tstms = Hail 2+ and/or Wind 65KT/75 MPH
Slide 7
Increase risk categories to 5 levels for Day 1, Day 2, &
Day 3 Outlooks Replace See Text with Marginal for lowest risk
probabilities (Day 1 - Day 3) Insert Enhanced between high-end SLGT
& low-end MDT probabilities Day10%2%5%10%10% sig15%15%
sig30%30% sig45%45% sig60%60% sig Tor Wind Hail Day20%5%15%15%
sig30%30% sig45%45% sig60%60% sig All Svr Day30%5%15%15% sig30%30%
sig45%45% sig All Svr Day4-815%30% All Svr TSTMS SLGT MARGINAL
ENHANCED MDT HIGH SPC Severe Weather Outlook
Probability-to-Categorical Description Tables (2014) Day 1-3
Outlook Changes sig = Significant Severe Tstms = Hail 2+ and/or
Wind 65KT/75 MPH
Slide 8
Increase risk categories to 5 levels for Day 1, Day 2, &
Day 3 Outlooks Replace See Text with Marginal for lowest risk
probabilities (Day 1 - Day 3) Insert Enhanced between high-end
Slight & low-end Moderate probabilities Add a 15 percent
(Slight Risk) to Day 4-8 Outlooks Day10%2%5%10%10% sig15%15%
sig30%30% sig45%45% sig60%60% sig Tor Wind Hail Day20%5%15%15%
sig30%30% sig45%45% sig60%60% sig All Svr Day30%5%15%15% sig30%30%
sig45%45% sig All Svr Day4-815%30% All Svr TSTMS SLGT MARGINAL
ENHANCED MDT HIGH SPC Severe Weather Outlook
Probability-to-Categorical Description Tables (2014) Day 4-8
Outlook Changes Expected to result in better alignment with WFO
forecasts and DSS
Slide 9
13Z Day 1 (Current) 6/1/2011 13Z Day 1 LSRs 6/1/2011 Example of
Change (Day 1) 13Z Day 1 (New) 6/1/2011
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SPC Outlook Changes Current Timeline for Implementing Changes:
September 2014
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Slide 12
Building a Weather-Ready Nation Impact Based Warning
Experimental Product
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Building a Weather-Ready Nation Impact Based Warning
Experimental Product Spring 2014 Expansion IBW began in 2012.
Positive feedback supported expansion to 38 central region offices
in 2013. Positive feedback supported expansion to 38 central region
offices in 2013. In 2014, six new offices, including NWS
Blacksburg, were added. In 2014, six new offices, including NWS
Blacksburg, were added. Expansion is expected in the future.
Expansion is expected in the future. IBW began in 2012. Positive
feedback supported expansion to 38 central region offices in 2013.
Positive feedback supported expansion to 38 central region offices
in 2013. In 2014, six new offices, including NWS Blacksburg, were
added. In 2014, six new offices, including NWS Blacksburg, were
added. Expansion is expected in the future. Expansion is expected
in the future.
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Building a Weather-Ready Nation Impact Based Warning
Experimental Product Goals: Provide additional valuable information
to media and Emergency Managers Provide additional valuable
information to media and Emergency Managers Facilitate improved
public response and decision making Facilitate improved public
response and decision making Better meet societal needs in the most
life-threatening weather events Better meet societal needs in the
most life-threatening weather events
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Building a Weather-Ready Nation Impact Based Warning
Experimental Product Intended Outcomes: Optimize the convective
warning system within the existing structure Optimize the
convective warning system within the existing structure Motivate
proper response to warnings by distinguishing situational urgency
Motivate proper response to warnings by distinguishing situational
urgency Realign the warning message in terms of societal impacts
Realign the warning message in terms of societal impacts
Communicate recommended actions/precautions more concisely
Communicate recommended actions/precautions more concisely Evaluate
ability to distinguish between low impact and high impact events
Evaluate ability to distinguish between low impact and high impact
events 2011 Raleigh EF3 Tornado?
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Building a Weather-Ready Nation Impact Based Warning
Experimental Product
Slide 17
Building a Weather-Ready Nation Tornado Radar Indicated or
Observed Impact Based Warning Examples
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Building a Weather-Ready Nation Tornado Tag: Considerable
Impact Based Warning Examples
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Building a Weather-Ready Nation Tornado Tag: Catastrophic
Impact Based Warning Examples
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Building a Weather-Ready Nation Severe Thunderstorm Warning:
Tornado Possible Impact Based Warning Examples
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Building a Weather-Ready Nation Impact Based Warning
Experimental Product Enhancements By: Improving communication of
critical information Improving communication of critical
information Making it easier to quickly identify the most valuable
information Making it easier to quickly identify the most valuable
information Enabling users to prioritize the key warnings in your
area of interest Enabling users to prioritize the key warnings in
your area of interest Providing different levels of risk within the
same product Providing different levels of risk within the same
product Enabling the NWS to express a confidence level of potential
impacts Enabling the NWS to express a confidence level of potential
impacts
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Building a Weather-Ready Nation Impact Based Warning
Experimental Product Evaluation: Performed by social science
research groups and National Weather Service Performed by social
science research groups and National Weather Service Using focus
groups and surveys Using focus groups and surveys Media partners
Media partners Emergency Management Emergency Management Public
Public NWS Forecasters NWS Forecasters
Slide 23
Building a Weather-Ready Nation Impact Based Warning
Experimental Product
http://www.weather.gov/survey/nws-survey.php?code=IBW
www.weather.gov/impactswww.weather.gov/impacts