Data Sources and Methods for the Weather Warning Index
Data
3.1 Data source
The index’s data sources include timeliness performance information for the identified six severe weather warning types. This information is compiled by comparing warnings issued by Environment Canada against severe weather reports submitted by the public and data collected by Environment Canada’s observation network.
Timeliness statistics reflect the average lead-time and target lead-time for each of the six warning types, as determined by our warning performance targets. Accuracy statistics reflect the Extremal Dependency Index (EDI), which incorporates the number of hits, misses and false alarms for each of the six warning types.
These statistics are compiled by Environment Canada from available meteorological observations, archived warning bulletins, and existing verification procedures. This information is available in the quarterly and annual reports from the Meteorological Service of Canada (MSC) warning program prepared by the Performance Management Division of the Business Policy Directorate.
3.2 Spatial coverage
Information reported in selected geographic regions for each warning group is used in calculating the WWI. These selected geographic regions are representative of Canada’s climate and are areas that regularly have sufficient event data against which to compare severe weather warnings.
Public forecast regions with those used in the WWI highlighted – rainfall, snowfall, freezing rain and wind warnings
Note: Some public forecast regions are not visible at the national scale. See Table 1 for the complete list.
| Pacific and Yukon | Prairie and Northern | Ontario | Quebec | Atlantic |
|---|---|---|---|---|
| Metro Vancouver | City of Winnipeg | Windsor – Essex – Chatham-Kent | Metro Montreal - Laval | Saint John and County |
| Fraser Valley- West Including Abbotsford | Thompson – Nelson House – Split Lake | London - Middlesex | Quebec | Moncton and Southeast New Brunswick |
| East Vancouver Island | City of Regina | City of Hamilton | Saguenay | Halifax Metro and Halifax County West |
| Greater Victoria | City of Saskatoon | City of Toronto | Rimouski – Mont Joli | Charlottetown (Queens County P.E.I.) |
| North Coast – Inland Sections | Prince Albert – Shellbrook – Spiritwood – Duck Lake | City of Ottawa | Forillon National Park - Gaspe - Perce | Sydney Metro and Cape Breton County |
| Central Okanagan – Including Kelowna | City of Calgary | North Bay – West Nipissing | Abitibi | Inverness County (Les Suetes Wind only) |
| West Kootenay | City of Edmonton | Greater Sudbury and Vicinity | Chibougamau | St. Georges (Wreckhouse Wind only) |
| Prince George | Yellowknife Region | Sault Ste. Marie – St. Joseph Island | Sept-Iles – Port-Cartier | Gander and Vicinity |
| BC North Peace River | Resolute | City of Thunder Bay | Blanc Sablon | St. John’s and Vicinity |
| Whitehorse | Iqaluit | Kapuskasing - Hearst | Fermont | Goose Bay and Vicinity |
| Kuujjuaq | Labrador City and Wabush |
Public forecast regions with those used in the WWI highlighted – severe thunderstorm warnings
Note: Some public forecast regions are not visible at the national scale. See Table 2 for the complete list.
| Pacific and Yukon | Prairie and Northern | Ontario | Quebec | Atlantic |
|---|---|---|---|---|
| Metro Vancouver | City of Winnipeg | Windsor – Essex – Chatham-Kent (Windsor - Leamington -Essex County) | Montréal métropolitain – Laval (l’ile de Montréal) | Saint John and County |
| Fraser Valley- West Including Abbotsford | Brandon – Carberry – Treherne (City of Brandon) | London – Middlesex (London - Parkhill - Eastern Middlesex County) | Vaudreuil - Soulanges – Huntingdon (Huntingdon) | Moncton and Southeast New Brunswick |
| East Vancouver Island | Dauphin – Roblin – Winnipegosis (R.M. of Dauphin including Sifton and Valley River) | City of Hamilton | Vallée du Richelieu - Saint-Hyacinthe (Saint-Hyacinthe – Acton Vale) | Halifax Metro and Halifax County West |
| Greater Victoria | City of Regina | City of Toronto | Lanaudière (Rawdon – Joliette) | Charlottetown (Queens County P.E.I.) |
| North Coast – Inland Sections | City of Saskatoon | City of Ottawa (Ottawa North - Kanata – Orléans) | Lachute - Saint-Jérôme (Lachute) | Sydney Metro and Cape Breton County |
| Central Okanagan – Including Kelowna | Prince Albert – Shellbrook – Spiritwood – Duck Lake (City of Prince Albert) | North Bay – West Nipissing (North Bay - Powassan – Mattawa) | Laurentides (Mont-Tremblant – Sainte Agathe) | Inverness County (Les Suetes Wind only) |
| West Kootenay | City of Calgary | Greater Sudbury and Vicinity | Haute-Gatineau - Lièvre – Papineau (Reserve Papineau-Labelle) | St. Georges (Wreckhouse Wind only) |
| Prince George | City of Edmonton | Sault Ste. Marie – Superior East (Sault Ste. Marie – St. Joseph Island) | Abitibi (Val D’Or – Louvicourt) | Gander and Vicinity |
| BC North Peace River | Lethbridge – Taber – Milk River (City of Lethbridge) | City of Thunder Bay | Estrie (Granby – Waterloo) | St. John’s and Vicinity |
| Whitehorse | Grande Prairie – Beaverlodge – Valleyview (Co. of Grande Prairie near Grande Prairie and Wembley) | Kapuskasing - Hearst (Kapuskasing - Hearst -Smooth Rock Falls) | Québec | Goose Bay and Vicinity |
| Lac Saint-Jean (Alma – Desbiens) | Labrador City and Wabush |
Marine forecast areas with those used in the WWI highlighted – gale warnings
Note: Some marine forecast areas are not visible at the national scale. See Table 3 for the complete list.
| Pacific and Yukon | Prairie and Northern | Ontario | Quebec | Atlantic |
|---|---|---|---|---|
| Strait of Georgia – South of Nanaimo | Great Slave Lake Basin | Western Lake Superior | Donnacona to Isle-aux-Coudres | Georges Bank |
| West Vancouver Island North | Tuktoyaktuk | Eastern Lake Superior | Tadoussac to Pointe-des-Monts | Sable |
| Queen Charlotte Sound - Western Half | Frobisher Bay | Northern Lake Huron | Pointe-des-Monts to Anticosti - southern half | Gulf – Magdalen |
| West Brevoort – southern half | Southern Lake Huron | Northeast Gulf | ||
| Barrow | Western Lake Erie | Southwest Coast | ||
| Lake Manitoba | Eastern Lake Erie | Northeast Coast | ||
| Lake Winnipeg – South Basin | Western Lake Ontario | Northern Grand Banks | ||
| Lake Winnipeg – North Basin | Eastern Lake Ontario |
3.3 Temporal coverage
To reduce volatility from year to year, a three-year moving average is used for reporting purposes. Data from calendar years 2009, 2010 and 2011 are used in the calculation of the first iteration of the index. Furthermore, the WWI will be updated annually. Each spring, a value is calculated for the previous calendar year using available information.
3.4 Data completeness
Data for selected geographic regions for each warning type are used in calculating the WWI. These regions are representative of Canada’s climate and are areas that regularly have sufficient event data against which to compare severe weather warnings.
3.5 Data timeliness
Data are available for each calendar by the end of February of the following year. The index will be updated each year in the spring with these data.
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