Convective Discussion
Rainfall warnings are continued for portions of the Maritimes. A large area of heavy precipitation with some embedded thunderstorms extends from Maine to the southwest coast of Newfoundland.
Our autostation at Sussex Corners reported an hourly rate of 30+ mm between 9 and 10 AM with the total for the area now exceeding 80 mm.
The rain will gradually end from west to east during the afternoon and evening.
Technical Discussion
A low pressure system currently over southeastern Maine will travel across Nova Scotia today and exit the province to the south of Cape Breton this evening. A warm front extends from the low eastward to PEI and then to Cape Breton. Radar is detecting a band of heavy showers (and isolated thunderstorms) from the lift provided by the warm front. South of the front the air is very moist, this is highlighted by the Gray and Yarmouth 12z soundings where both are showing precipitable water in excess of 50mm.
While the lightning activity has diminished along the warm front two other areas have now become the focus, in the warm sector a 30kt southwesterly low-level jet is fueling the already moisture-rich airmass resulting in a cluster of thunderstorms over the Baie Ste-Marie area – these storms were moving eastward at about 40 km/h. There is a good chance that these storms could reach the Valley and possibly the Southwest shore early this afternoon, and a slight chance for the rest of the mainland during the rest of the afternoon and early evening. Another area to consider for thunderstorm activity is in the vicinity of the low where a few strikes were detected during the morning.
Regional Impacts.
Southeastern NB and Northern and Eastern NS including Cape Breton: rain heavy at times with localized amounts of 50 to 100 mm
Rest of NS: Scattered thundershowers with brief heavier showers giving amounts of 20-40 mm.
Jean-Marc Couturier
