Summer forecast: A little warmer, a little wetter — but don’t bet on it
Have you ever noticed that we spend a lot of time wishing? On Monday we wish it was Friday. When we get back from vacation we wish we were going again, and when it’s cold we can’t wait for the warmer weather to arrive.
On March 20 we officially welcomed spring, the season so many waste wondering what summer will be like. It is one of the most frequent questions I get asked, second only to “what kind of winter can we expect?” It’s also one of the most difficult questions to answer.
In order to attempt it, meteorologists study the complex interactions between ocean, land and atmospheric conditions around the globe. At the top of the list of controlling features is the La Nina and El Nino effect. This fuelled by the warming and cooling of sea surface temperatures across the equatorial central and eastern Pacific. It has a significant influence on the jet stream and overall weather patterns around the globe.
This season we seem to be dealing with a weakening and almost non-existent La Nina, transitioning into a neutral state right now. A weak El Nino event is predicted to increase towards the fall. That, of course, takes us to peak hurricane season. During an El Nino Cycle, Atlantic hurricane activity is usually low due to an increase in wind shear over the tropics.
That analysis helps us see the big picture but it’s what happens locally that really sets the stage. In Atlantic Canada we are blessed to be surrounded by water. That water is not warm. So let’s start with a prevailing south wind in June; to most of us that sounds like a good thing. It is if you live away from the coast; a few days into that flow and, before you know it, temperatures are above normal. If you live along a south-facing coast- line, that same persistent south wind has been blowing across the Atlantic, which in June is not terribly warm. Your daytime temperature would not be much warmer than the ocean temperature.
So assessing the big picture and determining a seasonal forecast does not always reflect local conditions.
Back to the question: What does our summer look like?
We’ve been under a fairly active storm track during the past few weeks and I don’t see a significant change in the flow for a while. Heading into mid-spring and early summer, systems will be tapping into abundant Gulf and Atlantic moisture and that would result in above normal precipitation for Atlantic Canada.
We will continue to see those back and forth temperature swings for a while, but I expect slightly above seasonal temperatures toward the end of summer.
Forecasting for an entire season across all of Atlantic Canada is not my favourite thing but . . . you asked! Cindy Day is Saltwire Network’s Chief Meteorologist.