SPC Convective Outlook
Changes
Changes in Category
Names/Definitions
Bill Sammler
Warning Coordination Meteorologist
National Weather Service, Wakefield VA
http://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
Day 1-3 Outlook Changes
• 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
SPC Severe Weather Outlook Probability-to-Categorical Description Tables (2014)
Day1
0%
2%
5%
10%
10% sig
15%
15% sig
30% sig
45%
45% sig
Tor
TSTMS MARGINAL
Wind
TSTMS
MARGINAL
SLGT
ENHANCED
MDT
Hail
TSTMS
MARGINAL
SLGT
ENHANCED
MDT
Day2
0%
5%
15%
TSTMS
MARGINAL
SLGT
0%
5%
15%
All Svr
TSTMS
MARGINAL
SLGT
Day4-8
15%
30%
All Svr
SLGT
ENHANCED
All Svr
Day3
ENHANCED
30%
SLGT
15% sig
30%
MDT
30% sig
45%
30%
30% sig
45% sig
MDT
ENHANCED
45%
60% sig
HIGH
ENHANCED
15% sig
60%
60%
HIGH
60% sig
HIGH
45% sig
MDT
“sig” = Significant Severe
Tstms = Hail 2+ and/or
Wind ≥ 65KT/75 MPH
Day 1-3 Outlook Changes
•
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)
SPC Severe Weather Outlook Probability-to-Categorical Description Tables (2014)
Day1
0%
2%
5%
10%
10% sig
15%
15% sig
30% sig
45%
45% sig
Tor
TSTMS MARGINAL
Wind
TSTMS
MARGINAL
SLGT
ENHANCED
MDT
Hail
TSTMS
MARGINAL
SLGT
ENHANCED
MDT
Day2
0%
5%
15%
TSTMS
MARGINAL
SLGT
0%
5%
15%
All Svr
TSTMS
MARGINAL
SLGT
Day4-8
15%
30%
All Svr
SLGT
ENHANCED
All Svr
Day3
ENHANCED
30%
SLGT
15% sig
30%
MDT
30% sig
45%
30%
30% sig
45% sig
MDT
ENHANCED
45%
60% sig
HIGH
ENHANCED
15% sig
60%
60%
HIGH
60% sig
HIGH
45% sig
MDT
“sig” = Significant Severe
Tstms = Hail 2+ and/or
Wind ≥ 65KT/75 MPH
Day 1-3 Outlook Changes
• 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
SPC Severe Weather Outlook Probability-to-Categorical Description Tables (2014)
Day1
0%
2%
5%
10%
10% sig
15%
15% sig
30% sig
45%
45% sig
Tor
TSTMS MARGINAL
Wind
TSTMS
MARGINAL
SLGT
ENHANCED
MDT
Hail
TSTMS
MARGINAL
SLGT
ENHANCED
MDT
Day2
0%
5%
15%
TSTMS
MARGINAL
SLGT
0%
5%
15%
All Svr
TSTMS
MARGINAL
SLGT
Day4-8
15%
30%
All Svr
SLGT
ENHANCED
All Svr
Day3
ENHANCED
30%
SLGT
15% sig
30%
MDT
30% sig
45%
30%
30% sig
45% sig
MDT
ENHANCED
45%
60% sig
HIGH
ENHANCED
15% sig
60%
60%
HIGH
60% sig
HIGH
45% sig
MDT
“sig” = Significant Severe
Tstms = Hail 2+ and/or
Wind ≥ 65KT/75 MPH
Day 4-8 Outlook Changes
• 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
SPC Severe Weather Outlook Probability-to-Categorical Description Tables (2014)
Day1
0%
2%
5%
10%
10% sig
15%
15% sig
30% sig
45%
45% sig
Tor
TSTMS MARGINAL
Wind
TSTMS
MARGINAL
SLGT
ENHANCED
MDT
Hail
TSTMS
MARGINAL
SLGT
ENHANCED
MDT
Day2
0%
5%
15%
TSTMS
MARGINAL
SLGT
0%
5%
15%
All Svr
TSTMS
MARGINAL
SLGT
Day4-8
15%
30%
All Svr
SLGT
ENHANCED
All Svr
Day3
ENHANCED
30%
SLGT
15% sig
30%
MDT
30% sig
45%
30%
30% sig
45% sig
MDT
ENHANCED
45%
60% sig
HIGH
ENHANCED
15% sig
60%
60%
HIGH
60% sig
HIGH
45% sig
MDT
Expected to result in better alignment with WFO forecasts and
DSS
Example of Change (Day 1)
13Z
13ZDay
Day11(New)
(Current)
6/1/2011
6/1/2011
13Z Day 1 LSRs
6/1/2011
SPC Outlook Changes
Current Timeline for
Implementing Changes:
September 2014
Impact Based Warning
Experimental Product
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.
• In 2014, six new offices,
including NWS Blacksburg,
were added.
• Expansion is expected in
the future.
Building a Weather-Ready Nation
Impact Based Warning
Experimental Product
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
Building a Weather-Ready Nation
Impact Based Warning
Experimental Product
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?
Building a Weather-Ready Nation
Impact Based Warning
Experimental Product
Building a Weather-Ready Nation
Impact Based Warning Examples
Tornado – Radar Indicated or Observed
Building a Weather-Ready Nation
Impact Based Warning Examples
Tornado – Tag: Considerable
Building a Weather-Ready Nation
Impact Based Warning Examples
Tornado – Tag: Catastrophic
Building a Weather-Ready Nation
Impact Based Warning Examples
Severe Thunderstorm Warning: Tornado Possible
Building a Weather-Ready Nation
Impact Based Warning
Experimental Product
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
Building a Weather-Ready Nation
Impact Based Warning
Experimental Product
Evaluation:
• Performed by social science research groups and National Weather Service
•
•
•
•
•
Using focus groups and surveys
Media partners
Emergency Management
Public
NWS Forecasters
Building a Weather-Ready Nation
Impact Based Warning
Experimental Product
http://www.weather.gov/survey/nws-survey.php?code=IBW
www.weather.gov/impacts
Building a Weather-Ready Nation
The End!!
Are There Any
Additional
Questions?
william.sammler@noaa.gov
phil.hysell@noaa.gov