Technical Discussion
A large area of high pressure dominates Atlantic Canada bringing with it wide scale subsidence and very dry upper levels. There is no convective activity expected over the region today or tonight except possibly over southern Maritime marine waters as an area of low pressure tracks over that area. These thundershowers are not expected to be severe.
Regional Impacts
None
Barrie MacKinnon
Convective Discussion
No thunderstorms expected over the Atlantic provinces.
Jean-Marc Couturier
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
Convective Discussion
No Thunderstorms are expected today for the Atlantic Provinces as a sharp change in the airmass with cooler temperatures and lower dewpoints across the region.
Regional Impacts
Non expected.
Mel Lemmon
Convective Discussion
Convective activity is expected to be confined to the southern Maritimes and southern Newfoundland today. Elsewhere the passage of a cold front mitigates convection for today. The primary threat zone is Nova Scotia from Halifax east. Heavy downpours of rain are the most likely impact. However, strong wind gusts less than 90 km/h and small hail are also possible.
Another area to watch is southern Newfoundland where heavy rain is a concern. There is an area of heavy rain and t-shwrs offshore heading toward the Avalon and Burin Peninsulas that will arrive early this afternoon. Heavy showers and tshwrs will persist into the evening.
Technical Discussion
There is an approaching mid level trough and associated cooling aloft that will destabilize the column this afternoon and this evening over the threat area. There is 30 knots of unidirectional shear over the threat area. The 250 mb winds are around 50 knots over the threat area. CAPEs are in the 600-900J/kg range once initiation occurs.
Regional Impacts.
Srn NS and srn NB.
Hatt