Presentation on theme: "Severe weather warnings. Some definitions Natural Hazard: Weather or flood-related situation with potential to inflict loss or damage to the community."— Presentation transcript:
Severe weather warnings
Some definitions Natural Hazard: Weather or flood-related situation with potential to inflict loss or damage to the community or environment. While hazard may induce a crisis, they do not necessarily lead to disasters. Natural Disaster: A catastrophic event caused by a natural hazard that severely disrupts the fabric of a community and usually requires intervention of government to return the community to “normality”.
Some definitions In some instances, natural disasters can not be prevented from occurring, however their overall impact can be significantly reduced through Disaster Mitigation. Disaster mitigation: Process of managing the “risks” associated with potential natural disasters so that loss may be minimized and even eliminated. - Appropriate Response actions Disaster risk: The likelihood of harmful consequences arising from the interaction of natural hazards and the community.
Some definitions Risk = Hazard Probability x Vulnerability Nature of Hazard: Understand hazards of the past, monitoring of present, and predicting the future. Vulnerability: The extent of a communities susceptibility or resilience to loss or damage from a natural hazard. Reducing disaster vulnerability requires increasing knowledge about the likelihood, consequences, imminence and presence of natural hazards, and empowering individuals, communities and public authorities with that knowledge to lower the risk before severe weather events, and respond immediately during and afterwards.
Early warning Empower individuals and communities to respond appropriately to a threat in order to reduce the risk of death, injury, property loss and damage. Provide early warning of weather, water and climate hazards, for operational decisions Support risk and impact assessments to determine who is at risk and why To improve forecasts and analyses to help reduce or remove risks
Temperature: Very Cold conditions Maximum Temperature below 10 degrees Celsius Minimum Temperature below -10 degrees Celsius
Temperature: Very Cold conditions Maximum Temperature below 10 degrees Celsius Minimum Temperature below -10 degrees Celsius L L L Very Cold conditions: Meteorology EUMETSAT MSG: Air-mass image 26 August h00Z Cold air moving from the far south
Temperature: Very Cold conditions Maximum Temperature below 10 degrees Celsius Minimum Temperature below -10 degrees Celsius Very Cold conditions: High Risk areas EUMETSAT MSG: Air-mass image 26 August h00Z Mountains High lying areas Sutherland
Temperature: Very Cold conditions Maximum Temperature below 10 degrees Celsius Minimum Temperature below -10 degrees Celsius Wind Chill conditions EUMETSAT MSG: Air-mass image 26 August h00Z The colder effect that are felt on the skin as a result of cooling effect of the wind. Felt on the skin and eventually the whole body.
Temperature: Wind chill Sensible temperature less than or equal to -15 degrees Celsius Effects are worse under wet conditions
Very Cold conditions: At Risk People Mountaineers, climbers and hikers Homeless people People in informal settlements Added risk of FIRES Senior citizens Pets The sick Increase electricity usage
Temperature: Very High Maximum Temperature 40 degrees Celsius and above
Temperature: Very uncomfortable Discomfort Index of 38 degrees Celsius and above High temperatures and High humidity
Temperature: Effects Maximum Temperature 40 degrees Celsius and above Sunburn Danger Hikers Sports Diminishing Water Resources Traffic jams
Temperature: Heat-wave Three consecutive days when the Maximum temperature is expected to be at least 5 degrees higher than the average High Maximums of the hottest month.
Temperature and Wind: Veld Fires Weather conditions that could lead to runaway fires. Depends on Temperature, wind conditions, humidity, condition of fuel etc. Climate change: Longer fire season for west coast and adjacent interior, central Western Cape
Wind: Gale force winds or higher Winds speeds greater than 35kt or 65km/h Risk of falling, fallen and blowing debris Major effect on fishing Industry particularly off west coast
Wind: Widespread sandstorms Scouring effect Very low visibility Dangerous road conditions Dangerous flying conditions Normally in windy, low vegetative areas: West coast north of Lamberts Bay May become more prevalent in climate change scenarios
Temperature: Black frost The freezing of plant sap that results in black appearance Of the plants. Farmers and Gardeners
Wind: Tornadoes Harrismith Manenberg, 1999
Springbok!! In 2008
Severe Thunderstorms Lightning: Electricity spikes and power outages Traffic jams:Obvious danger to Aviation
Hail stones more than 19mm Property damageCrop damage
Heavy rain 80% probability of precipitation greater than 50mm over 24 hours Very low visibility and slippery roads Dangerous road conditions May flood low lying areas
Maritime: Waves higher than 5m, 7m Abnormal wave height High waves Offshore drilling Fishing Industry
Maritime: Tropical cyclones Lightning Storm Surge Heavy rain and flooding Huge waves
Aviation: Large Hail
Aviation: Severe Turbulence and Mountain waves
Aviation: icing and Ice accretion
Aviation: Volcanic Ash
Regional Specialist Meteorological Centre Heavy rainfall Strong Winds
Early warning Strive to ensure that every person or organization at risk Receives the information Understands the information BELIEVES the information Personalizes the risk Make correct decisions Respond in a timely manner
Early warning Effective early warning should be: Short, concise, understandable and actionable What, where, when, why, how to respond Should be presented in several different formats – text-graphics-color coded categories-audio; should included specific actions for people to take to respond to the event.
ains_winter.jpg res/thunderstorm.jpg Early warning