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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

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.

Table 1: Public forecast regions used in the WWI for rainfall, snowfall, freezing rain and wind warnings
Pacific and YukonPrairie and NorthernOntarioQuebecAtlantic
Metro VancouverCity of WinnipegWindsor – Essex – Chatham-KentMetro Montreal - LavalSaint John and County
Fraser Valley- West Including AbbotsfordThompson – Nelson House – Split LakeLondon - MiddlesexQuebecMoncton and Southeast New Brunswick
East Vancouver IslandCity of ReginaCity of HamiltonSaguenayHalifax Metro and Halifax County West
Greater VictoriaCity of SaskatoonCity of TorontoRimouski – Mont JoliCharlottetown (Queens County P.E.I.)
North Coast – Inland SectionsPrince Albert – Shellbrook – Spiritwood – Duck LakeCity of OttawaForillon National Park - Gaspe - PerceSydney Metro and Cape Breton County
Central Okanagan – Including KelownaCity of CalgaryNorth Bay – West NipissingAbitibiInverness County (Les Suetes Wind only)
West KootenayCity of EdmontonGreater Sudbury and VicinityChibougamauSt. Georges (Wreckhouse Wind only)
Prince GeorgeYellowknife RegionSault Ste. Marie – St. Joseph IslandSept-Iles – Port-CartierGander and Vicinity
BC North Peace RiverResoluteCity of Thunder BayBlanc SablonSt. John’s and Vicinity
WhitehorseIqaluitKapuskasing - HearstFermontGoose Bay and Vicinity
   KuujjuaqLabrador City and Wabush

Public forecast regions with those used in the WWI highlighted – severe thunderstorm warnings

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.

Table 2: Public forecast regions used in the WWI for severe thunderstorm warnings
Pacific and YukonPrairie and NorthernOntarioQuebecAtlantic
Metro VancouverCity of WinnipegWindsor – Essex – Chatham-Kent
(Windsor - Leamington -Essex County)
Montréal métropolitain – Laval
(l’ile de Montréal)
Saint John and County
Fraser Valley- West Including AbbotsfordBrandon – Carberry – Treherne
(City of Brandon)
London – Middlesex
(London - Parkhill - Eastern Middlesex County)
Vaudreuil - Soulanges – Huntingdon
(Huntingdon)
Moncton and Southeast New Brunswick
East Vancouver IslandDauphin – Roblin – Winnipegosis
(R.M. of Dauphin including Sifton and Valley River)
City of HamiltonVallée du Richelieu - Saint-Hyacinthe
(Saint-Hyacinthe – Acton Vale)
Halifax Metro and Halifax County West
Greater VictoriaCity of ReginaCity of Toronto

Lanaudière

(Rawdon – Joliette)

Charlottetown (Queens County P.E.I.)
North Coast – Inland SectionsCity of SaskatoonCity of Ottawa
(Ottawa North - Kanata – Orléans)
Lachute - Saint-Jérôme
(Lachute)
Sydney Metro and Cape Breton County
Central Okanagan – Including KelownaPrince 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 KootenayCity of CalgaryGreater Sudbury and VicinityHaute-Gatineau - Lièvre – Papineau
(Reserve Papineau-Labelle)
St. Georges (Wreckhouse Wind only)
Prince GeorgeCity of EdmontonSault Ste. Marie – Superior East
(Sault Ste. Marie – St. Joseph Island)
Abitibi
(Val D’Or – Louvicourt)
Gander and Vicinity
BC North Peace RiverLethbridge – Taber – Milk River
(City of Lethbridge)
City of Thunder BayEstrie
(Granby – Waterloo)
St. John’s and Vicinity
WhitehorseGrande Prairie – Beaverlodge – Valleyview
(Co. of Grande Prairie near Grande Prairie and Wembley)
Kapuskasing - Hearst
(Kapuskasing - Hearst -Smooth Rock Falls)
QuébecGoose Bay and Vicinity
   Lac Saint-Jean
(Alma – Desbiens)
Labrador City and Wabush

Marine forecast areas with those used in the WWI highlighted – gale warnings

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.

Table 3: Marine forecast areas used in the WWI for gale warnings
Pacific and YukonPrairie and NorthernOntarioQuebecAtlantic
Strait of Georgia – South of NanaimoGreat Slave Lake BasinWestern Lake SuperiorDonnacona to Isle-aux-CoudresGeorges Bank
West Vancouver Island NorthTuktoyaktukEastern Lake SuperiorTadoussac to Pointe-des-MontsSable
Queen Charlotte Sound
- Western Half
Frobisher BayNorthern Lake HuronPointe-des-Monts to Anticosti - southern halfGulf – Magdalen
 West Brevoort – southern halfSouthern Lake Huron Northeast Gulf
 BarrowWestern Lake Erie Southwest Coast
 Lake ManitobaEastern Lake Erie Northeast Coast
 Lake Winnipeg – South BasinWestern Lake Ontario Northern Grand Banks
 Lake Winnipeg – North BasinEastern 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.