Abnormal 'Weather Bomb' underway; wind gusts of 140 km/h
Friday, October 5, 2018, 8:31 AM - We are only days into the month of October and many across the west are digging out from a foot of snowfall. But what's interesting is that the strongest storm that we've seen in months is only now underway, with heavy snowfall, far-reaching winds and blizzard conditions for some Canadians.
While all of this winter weather is going down, other parts of our country have been basking in sunshine and muggy, summer-like weather. How can this happen?
Meet: THE WEATHER BOMB.
DON'T MISS: Fall Forecast and a Winter Sneak Peek
WHAT IS A WEATHER BOMB?
A 'weather bomb' is an unofficial term for a low pressure system that’s central pressure falls 24 millibars in 24 hours. This process is known as explosive cyclogenesis or "bombogenesis" and is currently ongoing across parts of Canada.
WHY IS THAT A BIG DEAL?
The lower the central pressure, the stronger the storm. The deeper the low becomes, the more intense its wind field will be. For example, in a hurricane the central pressure drops to extreme low levels. Back in October of 1979, Typhoon Tip's pressure dropped to a staggering 870 mb in the western Pacific Ocean and still holds the lowest pressure recorded by a tropical cyclone. While we won't come close to this type of pressure, it's the rapid intensification (in combination with a couple of other fact that will generate destructive hurricane-force wind gusts (over 119 km/h).
EFFECTS SO FAR
- Rapid cyclogenesis began Wednesday night through Thursday across western Quebec; central pressure dropped 40 mb drop in 24 hours
- Temperatures across southern Ontario peaked into the 20s on Thursday; will rise again through Thanksgiving
- Gusts over 90 km/h were reported in parts of northern Ontario and Quebec Thursday
- Gusts over 110 km/h in Iqaluit, power outages reported in town
- Wind warnings in northern Quebec, eastern Labrador and southern Baffin Island; gusts 100-140 km/h Friday
CLICK TO PLAY: TIMING OF WEATHER BOMB
TIMING AND IMPACTS
The storm began its story across northern Ontario Wednesday night through Thursday as it intensified into Quebec, where it officially attained its 'weather bomb' status. On Friday, the storm had deepened even further and is affecting a large portion of northern Canada, from northern Quebec, Labrador and Nunavut. A large swath of snow will blanket areas from James Bay, Hudson Bay, up to Baffin Island including Iqaluit and the Labrador coast. While there will be snow, it's the winds that will be the fierce part of the storm.
As the low swirls overhead Friday, visibility within snow bands will drop to near zero as hurricane-force wind gusts of 120 km/h whip around. For southern Baffin Island, some gusts could exceed 140 km/h before the storm departs and shifts east into the Labrador Sea on Saturday. Power outages have already been reported across the region from Thursday night.
IS THIS NORMAL?
While residents in northern Canada are no strangers to powerful blizzards, the climatological statistics of a low this deep so early in the season is not common.
"Sub 950 mb extratropical lows are very rare, especially this early in the season," says Chris Doyle, a retired meteorologist from British Columbia. "[Below is] an ensemble forecast and climatological return period. So with respect to recent [climatology in the last 30 years] it hasn't happened."
As we work our way through our fall season into winter, we can look forward (or not) to more weather bombs in the future.