Guide to Environment Canada Marine Weather Forecasts

Synoptic Warnings

The term “synoptic warning” in this context means that that the geographic extent over which the warning applies is of larger scale. Synoptic warnings are issued for potentially hazardous marine weather events that affect a significant portion of the marine district, or multiple marine districts.

Synoptic warnings include the following four categories of winds and freezing spray:

  • Strong wind: Wind speed of 20 to 33 knots inclusive. Strong wind warnings are only issued for coastal or inland waters during the recreational boating season.
  • Gale-force wind: Wind speed of 34 to 47 knots inclusive.
  • Storm-force wind: Wind speed of 48 to 63 knots inclusive.
  • Hurricane-force wind: Wind speed of 64 knots or greater.
  • Freezing spray: Ice build-up rate on marine infrastructure 0.7 centimetres per hour or faster.

Note that synoptic wind warnings apply to the mean wind only. Synoptic wind warnings are not issued for wind gusts that happen to reach warning criteria.

Synoptic Warnings Appearance in Text Bulletins

In the text bulletin of the regular or updated marine forecast, synoptic warnings in effect will be stated in a headline immediately after the marine district names(s) to which the warnings apply (refer to section 5 of this Guide).

Synoptic Warnings Appearance on Weather.gc.ca

On EC’s Weather.gc.ca marine forecast website, synoptic warnings in effect will be highlighted by the red banner immediately below the marine district name(s) to which the warnings apply (refer to section 6 of this Guide).  Clicking on the banners will navigate the webpage user to a criteria description of the synoptic warning in effect.  This information is located under the Warnings Tab on the relevant marine district’s Forecast page.