Fiona will hit Nova Scotia as the strongest storm on record in Canada
Prior to Fiona, the Canadian Hurricane Center issued a hurricane watch for parts of Nova Scotia, Prince Edward Island, the Magdalen Islands and Newfoundland.
“Hurricane Fiona has the potential to be a significant weather event in Eastern Canada this weekend,” the Center tweeted.
Fiona is one of five different systems that meteorologists are watching closely in the Atlantic, which woke up at the height of hurricane season.
There’s also Tropical Storm Gaston, which is centered 375 miles west-northwest of the Azores on the northeast Atlantic. The Azores are under a tropical storm warning and could see conditions deteriorate Friday and remain inclement until late Saturday. Additionally, a tropical wave exiting the coast of Senegal in Africa could strengthen into a named storm in the coming days. There is also a disturbance midway between Africa and South America which may gradually develop. Another incipient storm that could deal a serious blow to the Gulf or the Caribbean is potentially of great concern.
Fiona’s approach to Canada
As of Thursday morning, Fiona was located just over 450 miles southwest of Bermuda, moving north-northeast at 13 mph. Maximum eyewall winds were estimated at 130 mph, classifying the storm as a Category 4 hurricane.
Hurricane warnings have been issued in Bermuda, where Fiona could make a close pass west of the island early Friday. Hurricane-force winds extend 70 miles from the center of the storm, making forecasts biting.
“Preparations … should be completed,” the National Hurricane Center wrote. Bermuda could see a few inches of rain, in addition to strong winds and choppy waves.
After sweeping over Bermuda, Fiona will accelerate northward, pulled a little westward by an approaching low pressure trough or band, exiting the US East Coast. This will send the storm into southeastern Canada, eastern Nova Scotia or the Gulf of St. Lawrence.
Because the storm will be moving north quickly, it won’t have much time to weaken, meaning it will still pack the punch of a Category 2 hurricane. It will possess a mix of storm characteristics tropical and high latitude.
“We call this a deep hybrid low pressure system, possessing tropical north-tropical and intense winter storm properties with very heavy rain and high winds,” wrote Environment Canada, the national equivalent of the US National Weather Service. “Most areas will experience hurricane force winds. Similar cyclones of this nature have caused structural damage to buildings.
Fiona has grounded dozens of flights. A JetBlue plane flew over the storm.
A storm of record strength and impact
The exacerbation of the effect will be a “pressure dipole”. This means a strong atmospheric pressure contrast over a short distance, in this case due to an intense high pressure dome southeast of Greenland. The steep gradient, or change in atmospheric pressure with distance, will funnel extremely strong winds into the vacuum-type low.
The low pressure system itself could set a record for the lowest air pressure anywhere in Canada. Models simulate a storm with an atmospheric pressure between 930 and 935 millibars. The lowest barometric pressure ever observed in Canada was 940.2 millibars at St. Anthony in Newfoundland on January 20, 1977. As a general rule, the lower the pressure, the stronger the storm.
The extreme air pressure gradient around Nova Scotia will bring wind gusts over 100 mph, fueling a 5-8 foot storm surge, which will inundate the coastlines with water and create dangerous conditions. In addition, 4 to 6 inches of rain will generate additional risks.
Over the open ocean, wave heights can approach 80 feet, and there is an outside chance that a few rogue waves can reach nearly 100 feet. In early September 2019, the remnants of Hurricane Dorian appeared to have caused a rogue 100-foot wave near Port aux Basques, Newfoundland.
Brian Tang, associate professor of atmospheric sciences at the University of Albany, tweeted that “Fiona will be [an] off the charts bad… generational storm for Nova Scotia.
Fiona could even deliver snow to parts of the Labrador Peninsula as the storm pulls very cold air to its northwest flank. Uninhabited areas of empty Canadian tundra can pick up up to 10 inches.