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Questions for Claire

Archives: April

What are the weather predictions for summer 2009?

Thursday, April 23, 2009 | 03:32 PM PT

Question submitted by Lilly kaetler
(Abbotsford, BC)

Lilly, I get this question so often! Basically long range or "seasonal" forecasting is still a bit of a broad brush type forecast. You won't be able to make day to day decisions with it. So with that being said, the current seasonal forecast, don't hold your breath, for much of Canada is "near normal"!

Check out Environment Canada's forecast at http://www.weatheroffice.gc.ca/saisons/index_e.html.

There are some signs in the Equatorial Pacific Ocean of a slight El Nino developing - which would usually mean a slightly warmer and drier summer pattern for much of Canada. But again, at the moment, this is a very weak El Nino signal and may not materialise.

What is the key difference and definition between a wind gust and a squall?

Friday, April 3, 2009 | 10:01 AM PT

Question submitted by Parris
(Singapore)

Meteorologically speaking a wind gust is defined as the maximum 3-second wind speed that occurs (or is forecast to occur) within a 2-minute interval at a height of 10 meters above ground.

A squall however is a non-frontal line or belt of violent convective activity, sometimes seen with vigorous thunderstorms. Forecasters use the term "squall line" to describe a sudden wind-speed increase of 8 metres per second (29 km/hr) or more, for one minute or longer. It includes several briefer wind-speed changes, or gusts.

A squall however, is often named for the weather phenomenon that accompanies it, such as rain, hail, or thunder; a line squall is one associated with a squall line of thunderstorms that is often hundreds of kilometres long.

In Ontario for example, lake effect snow squalls are common features seen downwind of open and relatively mild water, in a cold windy winter airmass. They are intense, but of limited spatial extent and duration, periods of moderate to heavy snowfall, accompanied by strong, gusty surface winds and possibly lightning. Snow accumulation may be significant in the squall.