A monster is born: Damaging nor'easter facts and impacts
Friday, January 5, 2018, 11:35 AM - An impressive storm developed off the coast of North America at an unprecedented rate on Thursday.
Since then, it has reached 'weather bomb' status, delivered parts of northern Florida its first snowfall in nearly 30 years, and has meteorologists across the globe in awe over its rapid gain of power.
Here's what we've seen so far:
- Highest winds: Peak wind gusts of 170 km/h observed in Grand Etang, N.S. and 174 km/h in Wreckhouse, Newfoundland. Peak and record breaking gust of 119 km/h in Halifax, N.S.
- Highest snow: Bathurst, New Brunswick picked up 51 cm of snow (and counting) by Friday morning, which reported visibility of 400 metres and below for 10 hours.
- Thundersnow: Snow in Sydney, N.S. was falling at a rate of eight centimetres an hour with thundersnow and visibility under 200 metres reported.
- Wave heights: Two buoys recorded wave heights of 56 and 51 feet south of Nova Scotia.
- Atmospheric pressure: Saint John, N.B. recorded lowest atmospheric pressure at 951 mb.
- Highest wind gust: Peak wind gust of 76 mph or 122 km/h observed in Nantucket, Massachusetts.
- Highest snow: Plymouth, Maine picked up 56 cm of snow.
The set up was a record-breaking blast of Arctic air that migrated over an agitated region near the Gulf Stream – akin to lighting a match under a can of gasoline.
By chance, several pieces of energy, or shortwaves in the atmosphere, moved into position at exactly the right time.
The result was spectacular.
A lot of jargon is thrown out during extreme weather, but the baroclinic leaf is the initial sign of the storm rapidly intensifying (a great indicator of robust lift in the atmosphere). A powerful jet stream surged up towards New England, allowing the system to rapidly strengthen, as the baroclinic leaf and associated low expanded Wednesday evening.
But, there's another key indicator for a serious storm: the cinnamon bun swirl.
Not sure what I mean?
This occurs when the fronts wrap inward. This is also referred to as a bent-back occlusion, and it's often the business end of the storm. Consequently, it often features the strongest, most destructive winds of a nor'easter. If you don't see the cinnamon bun, how about a bicep flex, according to meteorologist Jonathan Erdman:
Achieving 'weather bomb' status:
50+ mb pressure drop has been measured according to the Weather Prediction Center analysis. For a storm to be officially declared a bomb-cyclone, the pressure has to plummet at least 24 millibars (mb) in 24 hours.
This low has deepened over twice that benchmark.
But, there's something else unusual about this storm. The track is also anomalous, especially when considering how deep of a pressure this system has attained.
Often low pressure systems can deepen to below 940 mb, but these are reserved for far northern latitudes such as the North Atlantic and North Pacific Ocean basins. These regions are notoriously known as breeding grounds for some of the strongest low pressure systems on earth.
But specifically, how low can the current low go? Sub 950 mb is a true possibility with our current low pressure system. What this translates to is widespread, damaging hurricane-force wind gusts for Atlantic Canada and a heightened risk of storm surge.
Check out this meteorological marvel for Thursday evening, as the low races towards the Bay of Fundy:
Maritimers, some of your barometers likely have never fallen this low before. It wouldn’t be surprising that several stations come close to all-time low pressure readings.
There are serious concerns that by Friday morning, parts of the coastline of Nova Scotia and the Maritimes will be significantly altered by coastal erosion and storm surge by this blockbuster storm. This is an extremely dangerous storm, and it must be taken seriously.
It's not just another nor'easter.