Chris Scott, Meteorologist
The track of this storm is key to predicting the precise impact in any one area. The graphic below shows remarkable agreement among computer model track forecasts which bring Irene into North Carolina early Saturday, near Long Island Sunday, and then rapidly through Maine Monday morning before the system is caught by the jet stream and whisked into Labrador Monday evening.
It is unlikely that the U.S. can avoid serious damage from Irene given this track. The possibility of the centre moving far enough east of New England to avoid serious flooding, wind damage and storm surge in the mid-Atlantic and northeast U.S. is getting smaller by the hour. Although Irene may only be a marginal category 1 hurricane as it nears Long Island, epic rainfall will lead to widespread flooding, and winds will be strong enough to knock down trees and cause widespread power outages.
The scraping of the U.S. coast and then direct hit on New England will knock down the strongest winds in the storm, and it will be substantially weaker by the time it affects Canada. However, there are 3 factors to worry about with tropical systems, and all 3 are concerns for Sunday into Monday morning: rain, wind and storm surge.
Canada will miss the epic 200 mm totals possible near New York, but 100+ mm are possible from Sherbrooke to Quebec City and east towards Edmunston. Rain will become heavier well in advance of Irene’s centre through the day on Sunday and peak in intensity Sunday evening before rapidly tapering off overnight. This amount of rain in a short period of time will likely cause significant flooding. The picture below shows rainfall totals along Irene’s track up the eastern seaboard. The track holds the key to who gets the most rain since the heaviest rain will fall west of the storm’s track.
The Maritimes will fall on the east side of the storm track and flooding is unlikely with the exception of extreme western New Brunswick. Wind will be the biggest concern across the Maritimes with gusts over 100 km/h possible. This is enough to bring down tree limbs and could lead to scattered power outages across all 3 Maritime provinces. Halifax will not take the direct hit it did with Earl, but Haligonians should be aware that Irene is not a miss. A broad area of strong winds will extend from St. Stephen all the way to Halifax on the east side of this system, and sweep through the Maritimes late Sunday night into Monday morning.
Storm surge is the great wild card with this storm. It appears the Bay of Fundy is at significant risk for seeing a storm surge given the likely track of Irene through Maine. The extent of storm surge flooding will depend on the exact track of the storm, its intensity, and the timing of its passage relative to high tide. These are important details the Canadian Hurricane Centre will be assessing over the weekend.
This is a significant storm for Quebec and the Maritimes and one that deserves our full attention. Fortunately it is not the historic storm it will likely be in the U.S.