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CINDY DAY: Rainfall numbers are not always an accurate measure of the season

Measured rainfall doesn't always tell a complete weather story.
Measured rainfall doesn't always tell a complete weather story. - Contributed

Like it or not, August is winding down. As far as meteorologists go, so too is summer; meteorological summer is June, July and August. 

It’s been a hot one for sure; records were set in terms of duration of high heat and humidity. As far as the rain situation goes, anecdotally, most would say it’s been very dry. If we turn to the numbers, we’ll find that July was very dry, but a very wet June brought up our summer rain totals. The exception is western Newfoundland and Labrador where the rainfall totals remain well below normal.

Buried within the rainfall snapshot, are interesting facts that are not obvious. For example, while the three-month rainfall for Sydney, N.S., was near normal, they received twice as much rain on Saturday as they did during the entire month of July.

Now people are already asking what fall is going to be like. Before I comment on that – and I don’t usually make season-long predictions – I want to quickly look back on why it’s been so hot and muggy. 

This summer, the Bermuda High, that large subtropical semi-permanent centre of high atmospheric pressure typically found south of the Azores in the Atlantic Ocean, sits much farther north than it usually does. The position of the system and the wind-field around it resulted in “Ontario heat” settling over Atlantic Canada. 

Over the next few weeks, I expect the controlling system to slowly sink southward. That more typical location for the system will allow the jet stream to flatten out and also sink southward, in turn allowing weather systems approaching from the west to move across Atlantic Canada. That will see periods of rain instead of hit-and-miss showers and will put an end to the flow of air from the tropics. Overall, I believe our fall will be a little on the wet side, with near or above seasonal temperatures.

Time will tell.

Cindy Day is the chief meteorologist for SaltWire Network.

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