Blocking pattern influences weather to welcome May

It wouldn’t be spring in Atlantic Canada without some upper-level blocking in our jet stream.

The upper-level ridge is centred near Hudson Bay and extends east to the south of Greenland. This blocking is driving a northerly flow into the region but also holding up low-pressure stuck offshore.

Newfoundland and Labrador will be most impacted by this setup with the low stalling and at times retrograding offshore with troughs spiralling around it and over the province.

Clouds will remain stubborn with periods of rain and drizzle for Newfoundland – especially in the east and along north-facing coastlines. Periods of mixed precipitation will roll through Labrador.

In the Maritimes it’s not as unsettled, but the position of this low coupled with the northerly component will keep more clouds than sunshine over northern and eastern areas of Nova Scotia and New Brunswick, along with P.E.I., for most of the week, with chances for showers and drizzle in the forecast.

While some showers or drizzle won’t be ruled out farther south and west in Nova Scotia and New Brunswick, it’s drier on average with greater opportunities for sunshine. However, all three Maritime provinces are expected to see scattered showers Friday and Friday night.

I then expect the ridge to weaken and sink southward this weekend. That should push the offshore low east and allow for some nicer weather with a general mix of sun and cloud around the region, and dry conditions for most.

There is a disturbance that I’ll be watching late Sunday through Monday that could deliver more widespread wet weather.

Except for parts of northern and eastern Newfoundland where 10 to 30-plus mm of rain is possible over the next few days, there’s not a whole lot of precipitation accumulation in the forecast. While we’re in a better situation compared to last April, we’ll want to monitor this trend closely.

Temperature-wise, where winds blow onshore it will remain near and below normal with near and above normal temperatures where winds blow offshore. A more widespread shift to near and above normal temperatures is possible later this weekend into next week.