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CINDY DAY: Wondering about warnings…

Heavy rainfall combined with high tide for disastrous effects in Mill Creek, Cape Breton, N.S.  This photo, taken on Thursday by Jules Anne, shows a truck parked on the wharf!
Heavy rainfall combined with high tide for disastrous effects in Mill Creek, Cape Breton, N.S. This photo, taken on Thursday by Jules Anne, shows a truck parked on the wharf! - Contributed

There is so much information coming at us that it can be hard to keep it all straight; that’s true about a lot of things, even the weather. 

Early last week, as forecasters started to get a handle on the potential impact of the developing weather system, weather statements were issued for all of Atlantic Canada.  At the peak of last week’s powerful nor’easter, there were more than 40 weather warnings in effect and almost as many watches and statements.  Many of you have reached out with concerns about the labels used.  

Let’s start with the weather statement.  The purpose of a weather statement is to explain.  It’s issued to highlight significant weather but can also express uncertainty about a system that’s been on the radar.  It’s issued when forecasters are tracking some developing weather that eventually could warrant watches or warnings.  In other words: “…keeping an eye on something.” 

Watch:  When a system’s impact becomes clearer and forecasters expect that it has the potential to serve up significant weather, a watch is issued.     

Warning: As certainty increases, watches can be upgraded to warnings. They are issued when significant weather is imminent and are issued six to 24 hours in advance of the start of the weather.  

Each type of weather, be it wind, snow or rain, has its one criteria that varies across the country.  

For Atlantic Canada, winter rainfall warnings are issued when 25 mm or more of rain is expected within 24 hours.  That number varies regionally; for B.C., a winter rainfall warning is issued when 50 mm or more of rain is expected in 24 hours.  And those numbers change for summer warnings. 

As far as snowfall warnings go, they’re issued when 15 cm of snow is expected in 12 hours or less, or 20 cm of snow in 24 hours or less.   

When all is said and done, you might notice weather bulletins.  These are issued after a weather event has passed.  They are a summary of significant weather and can include snowfall amounts, rainfall totals, peak wind gusts, etc.  

Every day you hear, see or read the weather, but understanding the weather products and forecasts will give you a leg up and hopefully keep you safe!

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