© Crown copyright Met Office Developing and Communicating Warnings Sarah Davies UK Met Office Wednesday 17 th April 2013

© Crown copyright Met Office

Developing and Communicating WarningsSarah Davies UK Met Office

Wednesday 17th April 2013


In this session

• Using the UK Met Office National Severe Weather Warning Service (NSWWS) as an example

• Understand what makes a weather warning effective

• Essential elements of an effective warning

• Communicating warnings

• Communicating uncertainty

• Verifying warnings


What makes a weather warning effective

Effective

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Criteria for issuing a warning

• Need to find out• what types of weather affect the general

public and emergency/disaster responders• If it doesn't affect them, do you need a

warning?• Establish and research

• which types of weather need a warning and why

• how much rain has to fall or how strong does the wind need to be to warrant a warning?

• if thresholds or potential impacts are the best measure for issuing a warning


Criteria for issuing a warning

• Thresholds• 20mm/hr• 30mm/hr• 40mm/hr• 10mm/24hr• 50mm/24hr• 50mph gusts• 60 mph gusts• 2m tidal surge

• Impacts• Saturated ground/Large

puddles• Flooding of agricultural land

from rainfall/ from river bursting banks/coastal

• Flooding of road networks from rainfall/ river bursting banks/coastal

• Flooding of towns/cities from rainfall/ river bursting banks/coastal

• Trees blown down/boats overturned/ power cables brought down

Which is more important?


History of NSWWSGreat Storm 1987


UK Severe weather

• Severe Gales• Heavy Snow• Heavy Rain• Dense Fog• Freezing rain/widespread icy roads• Heat wave

Exceptionally severe when:

• Severe gales/storms

• Very heavy snowfall, blizzards, drifting snow

All based on meteorological thresholds


National Severe Weather Warning Service

• Warns community of severe or hazardous weather

• Widespread disruption of communications

• Transport difficulties

• Threat to lives, welfare, property



THREE TIERS

• ADVISORY

• Issued daily at around11am

• EARLY WARNING

• Issued several days in advance of the severe weather (typically 3-5 days)

• FLASH

• Issued when the severe weather is imminent (up to 6 hours in advance)


Severe/Extreme

• Severe weather – these events are not unusual and are experienced on a number of occasions throughout the year, but more commonly winter months. They will impact on individual areas, but often not significantly.

• Extreme weather – these events are unusual and only happen around 3 or 4 times per year. They have a significant impact on infrastructure and may lead to casualties.


Early Warnings

• Issued in advance of the expected severe weather (typically 3-5 days)

• Assessment of the risk of disruption when it is above 60%

• Each region is assigned percentage risk of disruption (impact based)

• Disruption map published on website

• Allows time for preparations to be made

• Once issued, updated daily until the event


Early Warning on the web 1/2/09


Flash Warnings

• Issued when the severe weather is imminent (target of 2 hours, up to 6 hours in advance)

• Issued if certain critical meteorological thresholds are likely to be met with an 80% probability

• Issued on county/local authority basis

• React to rather than prepare for


An evolving process

In 2009, we asked our stakeholders about:

• Usefulness of warnings

• Timeliness

• Clarity


• We worked with partner agencies to develop a risk matrix

• The alert/warning will provide a combination of• The potential impact the weather will have• The likelihood of the weather happening

NSWWS since 2011


Likelihood

• Allows us to communicate uncertainty

• In general uncertainty is greater at longer lead times

• Most alerts at 3 to 4 day lead time will be assigned a low/very low likelihood


Generic Impacts


Impactshttp://www.metoffice.gov.uk/weather/uk/advice/

Very Low Low Medium High

Impact and advice associated with SNOW

Small amounts of snow lying on roads and pavements so some slippery road surfaces possible.Traffic may move generally slower than normal.Take extra care when walking, cycling or driving in affected areas.

More widespread snow lying on roads and pavements but road networks generally open.Care needed with only localised travel disruption.Problems mostly confined to usual prone areas.Take extra care when walking, cycling or driving in affected areas.Journeys through affected areas may take longer than usual.

Widespread snow with a number of road closures, others passable only with care.BE PREPARED for some disruption to road, rail and air transport with difficult driving conditions likely and longer journey times.

Widespread deep snow with many roads closed or impassable.Roads likely to become impassable with high risk of drivers becoming stranded.Significant disruption to road, rail and air transport.Risk to personal safety.Expect significant disruption to normal day to day life as a result of transport issues, school closures etc.Avoid making unnecessary journeys.

Other impacts specific to rain, wind, ice and fog also listed.

http://www.metoffice.gov.uk/weather/uk/advice/


Colour of warnings (Impact Matrix)

• Colour determined by combination of likelihood and impact

• Matrix below shows a high likelihood of a medium impact event produces an AMBER warning


Severe Weather WarningsColour Codes

NO SEVERE WEATHER EXPECTEDKeep up to date with latest forecast

BE AWARE Remain alert and keep up to date with latest forecast

BE PREPAREDRemain vigilant, keep up to date with latest forecast and take precautions where possible

TAKE ACTIONRemain extra vigilant, keep up to date with latest forecast. Follow orders and any advice given by authorities and be prepared for extraordinary measures


Interpreting the colours

• ‘Be Aware’ means

• Remain alert and keep up to date with latest forecast

• ‘Be prepared’ means

• Remain vigilant, keep up to date with latest forecast and take precautions where possible

• ‘Take action’ means

• Remain extra vigilant, keep up to date with latest forecast. Follow orders and any advice given by authorities and be prepared for extraordinary measures


Impacts

• Important to ascertain which impact column is being used

• Do not get into habit of dismissing yellow warnings/alerts

• “it’s only a yellow”

• Yellow could be a very low likelihood of high impacts


Access to warnings

• All warnings/alerts appear on the Met Office website and Hazard Manager

• http://www.metoffice.gov.uk/public/weather/warnings/

• Amber and Red Warnings are sent to Category 1 and 2 responders via a self registration scheme

• Email- pdf

• Email- plain text

• SMS

• Can select up to 3 emails, 1 sms, and 1 fax

http://www.metoffice.gov.uk/public/weather/warnings/


• Snow

• Ice

• Strong Winds

• Fog

• Heavy Rain



• Sent to ~850 organisations

• Over 2,500 delivery points, including…• Blue Lights (Police, Fire and Ambulance)• Central, regional and local government• NHS• Utilities• Media

Cascaded through individual organisations


Warnings on the webHomepage ticker banner


UK Warnings


Chief Forecasters Assessment


Communicating our forecasts and warnings - UK• Met Office website• Text and email alerts• Public Weather Service • TV and radio• You Tube• Twitter• Facebook• Flickr• Blog• Mobile Phone / Apps


Public Appreciation

90% of the public think Met Office weather warnings are useful


Communicating our forecasts and warnings• Met Office forecasts are broadcast on:

• BBC TV• BBC National Radio• BBC Local Radio• BBC websites• ITV and other commercial TV networks• Commercial Radio• Newspapers


BBC Weather Centre


We have two BBC TV studios


Verifying warnings

• Why do we need to?

• What do we need to know?

• How can we develop a severe weather database• Example from Met Office/UK• How could you do it in your country?


Why?

• What happened?

• Did we forecast it?• At the right time• In the right place• What were the impacts?

• Was the warning communicated effectively

• Improve understanding, better warning next time


What do we do?

• Verification

• Objective verification• Did we issue a warning when a threshold was

exceeded?

• Subjective verification• Did the warning give good advice• What happened? What were the impacts….


Subjective verification

• Verifying the impacts• Media reports• Twitter feeds• Impacts reported by responders

• Verifying the usefulness• Right place?• Right time?• Enough lead time?• Good advice?


On Call Log


How do we do it?

• On call log• Verification folder




How do we do it?

• On call log• Verification folder• Meetings each month• All data kept


How could you do it?

Things to think about

• How could you develop a severe weather database?

• What are your issues?

• How could you collect severe weather information from remote corners of the country?


Recap

• The National Severe Weather Warning Service uses a combination of LIKELIHOOD and IMPACT to give a single colour

• Easy to understand• Aims to change peoples behaviour• Use a variety of methods of communication• Verification is important to continually improve

• Work with stakeholders….


Questions?

Documents

© Crown copyright Met Office Developing and Communicating Warnings Sarah Davies UK Met Office Wednesday 17 th April 2013