SPC Convective Outlook Changes

SPC Convective Outlook Changes

Changes in Category Names/Definitions

Bill SammlerWarning Coordination Meteorologist

National Weather Service, Wakefield VAhttp://weather.gov/akq

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

Current SPC Outlooks

• 3 Tiers - SLGT, MDT and HIGH– “See Text” Used for

Marginal Situations• Increased Coverage

and Higher Intensity with MDT/HIGH

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

Day1 0% 2% 5% 10% 10% sig 15% 15% sig 30% 30% sig 45% 45% sig 60% 60% sig

Tor

Wind

Hail

Day2 0% 5% 15% 15% sig 30% 30% sig 45% 45% sig 60% 60% sig

All Svr

Day3 0% 5% 15% 15% sig 30% 30% sig 45% 45% sig

All Svr

Day4-8 15% 30%

All Svr

TSTMS

TSTMS

TSTMS

TSTMS

TSTMS

SLGT

SLGTSLGT

SLGT

SLGT

SLGT

MARGINALMARGINAL

MARGINAL

MARGINAL

MARGINAL

ENHANCED

ENHANCED

ENHANCED

ENHANCED

ENHANCED

ENHANCED

MDT

MDT

MDT

MDT

MDT

HIGHHIGH

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/orWind ≥ 65KT/75 MPH

• 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)


Tor

Wind

Hail


All Svr

Day3 0% 5% 15% 15% sig 30% 30% sig 45% 45% sig

All Svr

Day4-8 15% 30%

All Svr

TSTMS

TSTMS

TSTMS

TSTMS

TSTMS

SLGT

SLGTSLGT

SLGT

SLGT

SLGT

MARGINALMARGINAL

MARGINAL

MARGINAL

MARGINAL

ENHANCED

ENHANCED

ENHANCED

ENHANCED

ENHANCED

ENHANCED

MDT

MDT

MDT

MDT

MDT

HIGHHIGH

HIGH




• 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


Tor

Wind

Hail


All Svr

Day3 0% 5% 15% 15% sig 30% 30% sig 45% 45% sig

All Svr

Day4-8 15% 30%

All Svr

TSTMS

TSTMS

TSTMS

TSTMS

TSTMS

SLGT

SLGTSLGT

SLGT

SLGT

SLGT

MARGINALMARGINAL

MARGINAL

MARGINAL

MARGINAL

ENHANCED

ENHANCED

ENHANCED

ENHANCED

ENHANCED

ENHANCED

MDT

MDT

MDT

MDT

MDT

HIGHHIGH

HIGH




• 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


Tor

Wind

Hail


All Svr

Day3 0% 5% 15% 15% sig 30% 30% sig 45% 45% sig

All Svr

Day4-8 15% 30%

All Svr

TSTMS

TSTMS

TSTMS

TSTMS

TSTMS

SLGT

SLGTSLGT

SLGT

SLGT

SLGT

MARGINALMARGINAL

MARGINAL

MARGINAL

MARGINAL

ENHANCED

ENHANCED

ENHANCED

ENHANCED

ENHANCED

ENHANCED

MDT

MDT

MDT

MDT

MDT

HIGHHIGH

HIGH



Expected to result in better alignment with WFO forecasts and DSS

13Z Day 1 (Current)6/1/2011

13Z Day 1 LSRs6/1/2011

Example of Change (Day 1)13Z Day 1 (New)

6/1/2011

SPC Outlook Changes

Current Timeline for Implementing Changes:

September 2014

Building a Weather-Ready Nation

Impact Based WarningExperimental Product

http://www.nws.noaa.gov/com/weatherreadynation/



Spring 2014 Expansion • IBW began in 2012.

• Positive feedback supported expansion to 38 central region offices in 2013.

• In 2014, six new offices, including NWS Blacksburg, were added.

• Expansion is expected in the future.



Goals:• Provide additional valuable information to media and Emergency Managers• Facilitate improved public response and decision making• Better meet societal needs in the most life-threatening weather events



Intended Outcomes:• Optimize the convective warning system within the existing structure• Motivate proper response to warnings by distinguishing situational urgency• Realign the warning message in terms of societal impacts• Communicate recommended actions/precautions more concisely• Evaluate ability to distinguish between low impact and high impact events

2011 Raleigh EF3 Tornado?


Tornado – Radar Indicated or ObservedImpact Based Warning Examples


Tornado – Tag: ConsiderableImpact Based Warning Examples


Tornado – Tag: CatastrophicImpact Based Warning Examples


Severe Thunderstorm Warning: Tornado PossibleImpact Based Warning Examples



Enhancements By:• Improving communication of critical information• Making it easier to quickly identify the most valuable information• Enabling users to prioritize the key warnings in your area of interest• Providing different levels of risk within the same product• Enabling the NWS to express a confidence level of potential impacts



Evaluation:• Performed by social science research groups and National Weather Service• Using focus groups and surveys• Media partners• Emergency Management• Public• NWS Forecasters



http://www.weather.gov/survey/nws-survey.php?code=IBW

www.weather.gov/impacts

http://www.weather.gov/survey/nws-survey.php?code=IBW

The End!!Are There Any

Additional Questions?

[email protected]@noaa.gov

SPC Convective Outlook Changes

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