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Guide to Environment Canada Public Forecasts

Public forecast bulletins

There are two types of public weather forecast bulletins: the regular forecast bulletin, and the extended forecast bulletin.

The regular public forecast bulletin provides a description of the most significant weather conditions expected within the next two days (refer to Table 1 for exact time periods).

The extended forecast bulletin provides a description of the anticipated weather conditions beyond the time period covered by the regular public forecast bulletin: days three to seven. This extended forecast (also referred to as the long range forecast) is more general than the regular forecast. 

Issuing time of forecasts

Although there are some regional differences, the regular and extended public forecast bulletins are most commonly issued three times a day, at 5:00 a.m., 11:00 a.m., and 4:00 p.m. local time. Issue times of a few bulletins are different from the national standard due to time zone differences within a region.

Time period covered by forecasts

The following table indicates the time period that the forecast covers for each of the three above-mentioned forecast issue times.

Table 1 : Time periods for the public forecast bulletin
Forecast Issued at:TodayTonightTomorrowDays Three to Seven
5:00 a.m.5:00 a.m. to 6:00 p.m.6:00 p.m. to 6:00 a.m.6:00 a.m. to Midnight6:00 a.m. to 6:00 p.m.
11:00 a.m.11:00 a.m. to 6:00 p.m.6:00 p.m. to 6:00 a.m.6:00 a.m. to Midnight6:00 a.m. to 6:00 p.m.
4:00 p.m.N/A4:00 p.m. to 6:00 a.m.Tomorrow: 6:00 a.m. to 6:00 p.m.

Tomorrow night: 6:00 p.m. to 6:00 a.m.
6:00 a.m. to 6:00 p.m.

Below, the same information can be seen along a timeline:

5:00 a.m. forecast issue:

This type of graphic shows the time periods that are covered for a forecast issued at 5:00 a.m. The timeline starts with the Today period, which covers the times of 5:00 a.m. to 6:00 p.m. It moves on to the Tonight period, which covers the times of 6:00 p.m. to 6:00 a.m. It then goes into the Tomorrow period, which covers the times of 6:00 a.m. to midnight. Lastly, the timeline includes the Days Three to Seven period, which covers the times of 6:00 am to 6:00 p.m.

11:00 a.m. forecast issue:

This type of graphic shows the time periods that are covered for a forecast issued at 11:00 a.m. The timeline starts with the Today period, which covers the times of 11:00 a.m. to 6:00 p.m. It moves on to the Tonight period, which covers the times of 6:00 p.m. to 6:00 a.m. It then goes into the Tomorrow period, which covers the times of 6:00 a.m. to midnight. Lastly, the timeline includes the Days Three to Seven period, which covers the times of 6:00 am to 6:00 p.m.

4:00 p.m. forecast issue:

 This type of graphic shows the time periods that are covered for a forecast issued at 4:00 p.m. The timeline starts with the Tonight period, which covers the times of 4:00 p.m. to 6:00 p.m. It moves on to the Tomorrow period, which covers the times of 6:00 a.m. to 6:00 p.m. It then goes into the Tomorrow night period, which covers the times of 6:00 p.m. to 6:00 a.m. Lastly, the timeline includes the “Days Three to Seven” period, which covers the times of 6:00 am to 6:00 p.m.

Determination of forecast regions

Forecast regions are closely aligned with cities, communities and municipal boundaries. Local factors such as terrain, climatology, land cover and population patterns were used to define these regions. The names of the forecast regions generally correspond with those of the most prominent communities or the geographic regions. All official place names can be found in the Canadian Geographical Names Database.

Forecast time period terminology

Table 2 : Forecast time period terminology
DayTime Period TermTime Period (local time)Sub-Time Period TermSub-Time Period (local time)
*Note: There are no time qualifiers for days four to seven.
Terms for Days One & TwoMorning6:00 a.m. – noonEarly morning6:00 a.m. – 9:00 a.m.
   Late morning9:00 am – noon
 Afternoonnoon – 6:00 p.m.Early afternoonnoon – 3:00 p.m.
  Late afternoonLate afternoon3:00 p.m. – 6:00 p.m.
 Evening6:00 p.m. – midnightEarly evening6:00 p.m. – 9:00 p.m.
   Late evening9:00 p.m. – midnight
 Overnightmidnight – 6:00 a.m.  
 Near Noon  11:00 a.m. – 1:00 p.m.
 Near Midnight  11:00 p.m. – 1:00 a.m.
 After midnight  12.00 a.m. – 3.00 a.m.
 Before morning  4.00 a.m.– 6.00 a.m.

Terms for Day Three

(4 p.m. forecast only)

Morning6:00 a.m. – noon  
 Afternoonnoon – 6:00 p.m.Late in the Day3:00 p.m. – 6:00 p.m.

 

What information is included in the forecast?

Days One & Two:

The regular public forecast bulletin will always contain the following standard weather elements: (see the Weather Elements and when they are included in the forecast, for further details)

The following additional weather elements may also be included, provided certain criteria are met (see the Weather Elements and when they are included in the forecast for these criteria):

Days Three to Seven:

The extended public forecast bulletin will always contain the following standard weather elements (see the Weather Elements and when they are included in the forecast, for further details).

The following additional weather elements may also be included, provided certain criteria are met (see the Weather Elements and when they are included in the forecast for these criteria):

*Note: The normal temperatures for this period are the climatic normal temperatures for the grouping of regions indicated in the forecast. It is the Day Five normal temperature that is displayed in the extended bulletin. The normal temperatures can change as the grouping of regions in the forecast is changed.

The climatic normal temperatures are derived from 30-year averages of daily highs and lows. 

 

Sample forecast

SAMPLE forecast #1 from the Weatheroffice  

Sample forecast from the Weatheroffice web site.

  1. Navigational toolbar that allows you to quickly link to other meteorological products and educational resources offered by Environment Canada; from radar and satellite images, marine information to fact sheets and Frequently Asked Questions.

  2. The Forecast Quick Link lets you easily browse through each province to find your local weather forecast.

  3. The watch/warning/advisory banner will warn you of all latest weather watches, warnings and advisories in effect for your region.  Clicking on the banner will take you directly to the full details of the message.

  4. The Current Conditions box displays all available weather information for the location chosen, along with the time and date that the information is valid.

  5. Forecast Iconsgive a visual description of what the forecast is for the next 5 days.  The icons will show the sky condition/precipitation,COP, high temperature and low temperature for each day.

  6. The Forecast Text is the complete forecast and gives more information than the forecast icons.  In addition to the information given in the icons, the text is more descriptive and gives the wind speed and direction. 

  7. The More Info tabs throughout the city page are drop down menus that will give you quick links to other useful information that pertains to the block that they are in.  The top tab will link you to the past 24 hour conditions, radar imagery and satellite imagery; the middle one will link you to the text forecasts, air quality and the UV index forecast; while the bottom tab will link you to record values and historical weather.

  8. The Historical Data provides us with a quick summary of yesterday’s temperatures and precipitation, along with normal temperatures for the period, sunrise and sunset.

 

SAMPLE regular forecast (text bulletin)
The numbers provide a description of the forecast text.
1.FPCN11 CWTO 311450
Forecast for Southern Ontario and the National Capital Region
Issued by Environment Canada at 11:00 am EDT
Saturday 31 May 2008 for today and Sunday.
The next scheduled forecast will be issued at 3:30 pm.
2.Elgin
3.Severe Thunderstorm Watch in Effect
4.Today..Becoming cloudy. 60 percent chance of showers or thunderstorms this afternoon with the risk of a severe thunderstorm.Wind west 30 km/h gusting to 50. High 25 except 16 near Lake Erie.
UV index 9 or very high.
Tonight.. Clearing late this evening. Wind west 30km/h gusting to 50becoming light this evening. Low 10.
Sunday..A mix of sun and cloud. Wind becoming Northwest 20km/h
In the morning. High 20

1. This text is called the “title block”. It indicates the forecast area, the date & the time for which the forecast is. It also indicates when the next forecast will be issued.

2. The forecast region name(s) is the full name of the region(s) or metropolitan area(s) for which the forecast is issued.

3. These are called “status statements”. If there is a watch, warning or an advisory in effect for a forecast region(s), then status statements are indicated. 

4. The forecast text is broken into distinct periods (i.e. today, tonight, tomorrow) for ease of readability.

 

SAMPLE extended forecast (text bulletin)
The numbers provide a description of the forecast text.
1.FPCN51 CWTO 042019
Extended forecasts from Friday 6 March to Tuesday 10 March for Southern Ontario and the National Capital Region issued by Environment Canada at 3.30 PM EST Wednesday 4 March 2009.
The next scheduled forecast will be issued at 5.00 AM Thursday.
2City of Toronto.
3

Friday..A mix of sun and cloud. Windy. High 14.

Saturday..Cloudy with 60 percent chance ofshowers.Low plus 1. High 7.

Sunday..Periods of rain. Low plus 1. High 11.

Monday..Cloudy with 70 percent chance of rain showers or flurries.Low plus 1. High6.

Tuesday..Sunny. Low minus 4. High plus 5.Normals for the period..Low minus 6. High plus 3.

1. This text is called the “title block”. It indicates the forecast area, the date & the time for which the forecast is. It also indicates when the next forecast will be issued.

2. The forecast region name(s) is the full name of the region(s) or metropolitan area(s) for which the forecast is issued.

3. The extended forecast bulletin covers day 3 to day 7.

Forecast Revision

Forecasts are revised when the difference between the forecast and actual conditions are such that public security and safety are at risk and/or when inconvenience to the public is thought to be extensive. A revision to the regular public forecast bulletin is initiated when one or more of the following criteria have been satisfied:

  • The non-occurrence of forecast precipitation or hazards (freezing rain, definite forecast of thunderstorms, etc.) and vice versa.
  • A difference in precipitation type (snow as opposed to rain/freezing rain and vice versa).
  • A significant change in the timing of forecast event(s).
  • A marked change in temperature regime is expected but is not occurring and vice versa.
  • When, to the opinion of the supervisor on duty, the latest forecast does not reflect what is actually occurring and what is expected to occur in the next few hours.

The extended forecast is rarely revised, however if it is revised, one or more of the same criteria above would have to be met to warrant the change(s).

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