- Published: February 4, 2022
- Updated: February 4, 2022
- Language: English
- Downloads: 33
Summer Severe Weather Geoff Coulson Warning Preparedness Meteorologist Environment Canada Sept 11 2009 ICLR Friday Forum 1 Contents – – – – Ontario Storm Prediction Centre Forecasting Technology Watch/Warning Program A closer look at August 20th tornado outbreak 2 Ontario Storm Prediction Centre Toronto 3 Radar data… 4 Weather Technology 5 Satellite Data… 6 Computer Models… 7 Forecast Area of Responsibility 8 Scale of a Summer Storm 9 One storm covering part of a county Scale of a Winter Storm Snow L Heavy Snow Freezing Rain X Rain Showers One storm covering thousands of square kilometres 10 Severe Weather Lead Times – Summer Severe Weather (severe thunderstorms, tornadoes etc..) minutes to hours – Winter Severe Weather (heavy snow, freezing rain, strong winds etc..) — hours to days 11 Weather Watch vs. Weather Warning – Weather Watch means there is the potential for severe weather — Be Alert Weather Warning means that severe weather will soon occur or is occurring — Take Action Ron Gravelle – 12 Severe Thunderstorms — A Breed Apart – 5% of Ontario thunderstorms are categorized as severe each year… – Severe thunderstorm has one or more of the following characteristics — Wind gusts of 90 km/h or more — Hail of 2 cm diameter or larger (size of a nickel or larger) — Flooding rains — Tornado(s) 13 By the Numbers – On average around 120 summer severe events in Ontario each season (late April to early October) — — — — 70 due damaging winds 20 heavy rain/flooding 20 hail 11 tornadoes 14 Fujita Wind Damage Scale – F0 — winds up to 115 km/h — Shingle, siding damage – F1 — winds 120 to 170 km/h — Numerous shingles, partial roof removal – F2 — winds 180 to 240 km/h — Roof removed from well-built home – F3 — winds 250 to 320 km/h — Roof and some exterior walls removed – F4 — winds 330 to 410 km/h — 2 storey brick house left with only a few walls remaining – F5 — winds 420 to 510 km/h — Brick house destroyed to foundation 15 Tornado Characteristics – Duration – 5 minutes to 120 minutes – Speed of Motion – 30-70 km/h – Path length – Less than 1 km-150 km – Path Width – 10’s of metres – 2 km – Direction of travel – Usually southwest to northeast – IMPORTANT — Appearance of Tornado NOT an indication of its strength Ontario Tornadoes – Vast majority are either F0 or F1 – 1 F2 every year or so – 1 F3 every 8 years or so — Last confirmed Ontario F3 Violet Hill, April 20, 1996 — OVERDUE! – 1 F4 every 15 years or so — Last confirmed Ontario F4 Barrie and Grand Valley tornadoes, May 31, 1985 — OVERDUE! – No confirmed F5’s in Ontario — OVERDUE? 17 Tornado Warnings – Strong evidence on radar — Rotation at multiple levels in storm…however… — “ hook” echo – Credible Eyewitness/Video Report — CANWARN trained spotter — Police/Fire/Municipal Official — Multiple public reports/videos…right place at right time 18 CANWARN Storm Spotters 19 Project OPPortunity 20 CANWARN/OPP reports important… – Ground-truth info from radars, lightning detector and satellites – Help protect members of the affected community and communities where storm may be headed – Information could be used to issue/update Watches and Warnings 21 August 20th 2009 Tornado Outbreak Jeff Scheper 22 23 24 25 26 Staying on Top of the Weather Media Internet Weatheradio Cell Phone/PDA 27 Time to React – May be a few minutes or less – Not all storms will have a watch/warning – Not all storms will be easily visible — Haze — Rain — Surrounding hills or trees – Preparation before event is key — Check weather before going out…keep an eye on the sky — Where is my best shelter? — React… 28 Ways Forward – How do you alert people for the most significant of events? — National Alert System? – Red banner on TV – Interrupt radio broadcasts (syndicated programming?) — Cell phone alerting? – Liability for cell phone companies if system unable to handle all the alerts that need to go out? — Reverse 911? — Sirens? – Education — If caught outside do…. 29