Don't believe social media predictions of weekend 'bomb cyclone' in Halifax

Could Halifax see a bomb cyclone over the weekend? The short answer: No, says meteorologist Cindy Day.

The topic of a bomb cyclone weather system has been circling Halifax social media, but Day, who operates a weather service at cindayday.ca, said there is no possibility this weekend.

“It’s interesting that the bomb cyclone topic came up. I guess it was (Tuesday), people started talking about this bomb cyclone heading for the Maritimes, and so people started reacting and wondering if it was going to happen,” said Day.

So, what is a bomb cyclone and what weather conditions will Nova Scotians face this weekend?

A bomb cyclone is measured by its rapid intensification, dropping in pressure by at least 24 millibars within 24 hours. It usually comes with strong wind gusts, but Day said it doesn’t always.

Halifax has seen bomb cyclones damage property.

“In the fall, past bomb cyclones have been responsible for damaging wind and rain that changes to snow,” said Day.

A nor’easter could also be classified as a bomb cyclone if it experiences a significant drop in pressure.

On Thursday, the Halifax region is expected to see gusts of wind up to 40 or 50 km/h, following Wednesday’s rain.

“There is a system coming in that is going to bring us significant wind,” said Day. “Again, that’s not a bomb cyclone, but it’s just a very strong pressure gradient behind the rain.”

A low-pressure system will be coming to the region on the weekend, but Day said it is not expected to intensify or deepen.

“There is going to be a system going through with some rain Friday evening overnight, some showers Saturday and falling temperatures,” said Day.

“It is going to get colder through the day on Saturday . . . colder as the day goes on, little flurries in the air, but not excessive wind.”

In Cape Breton, there is a chance of up to four centimeters of snow this weekend, but Day said it’s not unusual to see snow in that region at this time of year.

While the data is not yet compiled to make comparisons, Day said this season seems windier than others.

“Anecdotally, I feel that we’ve had quite a bit of wind with the systems that have rolled through. The temperatures have fluctuated quite a bit,” said Day.

“So those temperature swings do traditionally bring high wind gusts, and I find that we’ve had our share of wind. So, it’s been pretty windy. That’s typical of a season that’s heading into an El Nino winter.”

The El Nino climate pattern is likely to bring higher wind gusts and more precipitation than average. It also could push off winter for a little while, said Day.

“I think that’s what we’re going to be looking at: a delayed start to winter, a lot of moisture and probably significant wind each time we get these rain events.”

In terms of beautiful fall leaves, Day said the delayed winter won’t make them last any longer, since leaves fall based on sunlight levels. But high wind levels could knock more off trees prematurely.