Tropical cyclone information statements and technical discussions
The Canadian Hurricane Centre issues two types of bulletins when a tropical cyclone is expected to bring tropical-storm force winds (gales 63-117 km/h) into Canadian territory or territorial waters within the next three days. The Tropical Cyclone Information Statement is a plain language bulletin designed for the public and media, whereas the Tropical Cyclone Technical Discussion provides technical details on the storm for specialized clients who need more detailed meteorological information.
The Canadian Hurricane Centre stops issuing these bulletins in any of the following circumstances:
- when the tropical cyclone has moved beyond our area of concern and is no longer bringing gales to Canada or Canadian waters AND any heavy rainfalls have also ended
- when the tropical cyclone has become extratropical and has lost most of its tropical characteristics (Note: regional Storm Prediction Centres will continue to issue routine forecasts and warnings)
- when the tropical cyclone has dropped below gale strength to tropical depression strength (37-62 km/h) AND any heavy rainfalls have ended (Note: The Canadian Hurricane Centre will continue issuing bulletins as long as heavy rains are falling)
Note: The Canadian Hurricane Centre stops issuing bulletins only after consulting with the affected regional Storm Prediction Centres.
Content of the Tropical Cyclone Information Statement
These bulletins, which are intended for the media and general public, provide non-technical storm-specific information. A bulletin header and information about the affected areas are followed by the following details:
- Section 1 - The storm’s current position, strength, present movement and central pressure
- Section 2 - Information on reported severe weather or impacts, and an overview of expected impacts (if predictable). This section also includes a summary of inland warnings issued by the Canadian Hurricane Centre or Storm Prediction Centres. Details on specific impacts are listed as follows just prior to the storm’s arrival:
- A: Wind
- B: Rainfall
- C: Surge/Waves
- Section 3 - Summary of marine warnings issued by the Storm Predication Centres, details of reported severe weather or impacts, and an overview of expected impacts (if predictable)
Content of the Tropical Cyclone Technical Discussion
These bulletins are intended for meteorologists and other clients with a technical or meteorological background who require more detailed meteorological information. They contain more technical detail and language. The bulletin provides details on the reasoning behind the analysis and forecast of a specific storm. It also includes tabular information for storm forecast positions and a wind radii table. In the Tropical Cyclone Technical Discussion a bulletin header is followed by the following details:
- Section 1 - The storm’s current position, strength, central pressure and present movement
- Section 2 - Information on the forecast position, central pressure and strength of the storm in tabular format
- Section 3 - A written technical discussion intended to convey the forecaster’s rationale on the current and forecast elements of the storm.
- A: Analysis - discussion of the current details of the storm and its environment
- B: Prognostic - discussion of the future details of the storm and its environment
- C: Predicted Wind Radii - A table of the predicted radii of recognized wind thresholds (e.g. gale force winds, storm force winds, hurricane force winds)
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