Polar air diving south triggers rainy week for Maritimes

Have the rain gear ready, you’ll need it Tuesday night and Wednesday. CTV Atlantic meteorologist Kalin Mitchell is tracking a round of chilly, wet weather.

Cold air from the north clashing with warmer air bottled up in the United States will fuel two low pressure systems for the Maritimes this week.

Both systems are directed towards us by the jet stream. A rainy Tuesday night and Wednesday will be followed by a second round of wet weather Friday into Saturday.

Rain develops west to east across the Maritimes Tuesday evening.

There is a lot of cold air located aloft right now so some wet snowflakes mixing in for northwestern New Brunswick are possible. I don’t expect any accumulation and a bit of snow in that part of the Maritimes isn’t uncommon for this month with the 30-year average being about three-to-four centimetres.

The rain carries on into Wednesday morning for the Maritimes before clearing, west-to-east, Wednesday afternoon into evening. A general 10 to 30 mm of rain with locally higher amounts of 30 to 50 mm is possible in southwestern Nova Scotia.

Here are some things to keep in mind for Wednesday:

• Lights and windshield wipers on for the morning commute. Give yourself time and space for the rainy roads.
• Watch footing. Leaves are coming down and can be slick underfoot when wet.
• Check ferry services for advisories or cancellations due to gusty winds.
• Risk to high sided vehicles travelling Margaree Harbour to Bay St. Lawrence in Inverness County – Cape Breton Peak gusts could reach 110+ km/h Wednesday afternoon until evening.

Round two Friday

The next system is a Texas low that rapidly gains strength between the boundary of the chill air from the north and milder conditions on the U.S. eastern seaboard.

Rain develops in New Brunswick during the day Friday with current timing having it mostly arrive for Prince Edward Island and Nova Scotia Friday evening and night.

That system looks to be another 10 to 30 mm of rain accompanied by gusty winds both during the rain and behind it for Saturday. I’d expect more travel advisories from the ferry services in the region for it.

In both cases, a westerly wind following the rain will bring some chilly air into the Maritimes.

• Thursday: Following the first system, most daytime high temperatures will be held in the 9 C to 13 C range. It will be a brisk and gusty day across the entire region. Overnight lows heading into Friday morning will plunge into the low-to-mid single digits, with a few areas approaching the freezing mark in New Brunswick.
• The weekend drop: The cold snap following Friday’s rain will be even more noticeable. Daytime highs for both New Brunswick and Prince Edward Island on Saturday will stay trapped in the single digits. Nova Scotia will start Saturday morning with milder temperatures in the low teens, but residents will feel the temperature steadily fall throughout the afternoon.
• Sunday: The week concludes with a much colder October Sunday for the Maritimes, featuring widespread daytime highs maxing out in the mid-to-high single digits.