While almost all of the coverage of Hurricane Arthur in both the American and global media focused on the storm's impact on North Carolina, the storm is still churning in the Atlantic and it has its sights set on Atlantic Canada.
As of 11:00 AM Eastern, a tropical storm warning was in effect for Cape Cod in Massachusetts, as Arthur's wind field will expand as the storm races northeast and begins its transition to a post-tropical cyclone (much the same process Hurricane Sandy underwent before landfall in 2012).
The storm's impact on Cape Cod will include high winds, heavy rain, and some coastal flooding. However, the most concerning aspect of the forecast is what will happen in the Canadian Maritimes.
A tropical storm warning is in effect for most of Atlantic Canada, including all of Nova Scotia and Prince Edward Island, and coastal areas of eastern New Brunswick from Gloucester County down through Charlotte County, including Saint John and Moncton.
Even though Arthur is expected to lose tropical characteristics, it will still be a large and dangerous storm by the time it hits the Maritimes. The storm will have close to hurricane-force winds by the time it makes landfall on the southern tip of Nova Scotia tomorrow morning. Tropical storm force winds will overspread the entire Maritimes region during the day on Saturday, with gusts exceeding hurricane force (119 km/h, or 74 MPH) at times, especially near where the center tracks, which current thinking brings along western Nova Scotia and over Prince Edward Island.
The storm's trajectory will bring a storm surge into southeastern Nova Scotia (especially Halifax Harbour) and coastal areas of New Brunswick that lie along the Bay of Fundy.
Environment Canada points out that flooding is a particular concern in areas that receive the heaviest rain, with rainfall rates exceeding 15 mm (half an inch) per hour in some spots. The U.S. Weather Prediction Center notes that a general 50-100 mm (2-4 inch) swath of precipitation is likely nearest to the center of the storm, with totals possibly exceeding 100 mm in eastern New Brunswick.
It's important to remember that the black line on the forecast maps denote the forecast track of the center of Hurricane Arthur, and that its effects (wind, rain, waves, and surge) will extend far beyond the center of the storm.
[Maps by the author using NHC data]