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#QuickTips- Understanding Marine Weather Forecasts and 'Isolated' vs. 'Scattered' Storms

By: Bill Jennings

Being able to understand what a marine weather forecast is telling you can be extremely helpful. But it is not always clear. To make weather reports more helpful, weathermen often add qualifying words to their forecasts, and just one word can change the meaning.

For example, I am often asked, what is the difference between isolated and scattered thunderstorms. From a boater’s perspective, which are worse? Yes, there is a difference. The prefix isolated, (ISOL) indicates that there is less than a 30% chance the area will experience measurable precipitation during the forecast period. The prefix scattered, (SCT) indicates that there is between a 30% and 50% chance that the area will experience measurable precipitation.

So, when the forecast is for isolated thunderstorms in one region, and scattered thunderstorms several kilometres to the north, the boater in the north will have a greater chance of getting wet (and a greater risk), than the boater in the south.

You can stay updated on live marine forecasts and warnings from the Government of Canada using their Weather Index. To learn how to interpret marine forecasts you can check out the Marine Weather Forecast Guide.

To get a better understanding of marine weather patterns and how to interpret data check out the helpful video below:

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