Convective Discussion
A cold front associated with a deep low over southern Quebec will move into New Brunswick this afternoon, and an associated trough moving into Nova Scotia will cross the province by overnight tonight. As the associated trough approaches Newfoundland, it may re-initiate convection over southwestern Newfoundland later today into tonight. Meanwhile a warm front moving north over Newfoundland today has triggered a few thundershowers along the South Coast, which should end this afternoon.
For the Maritimes the moisture is low, with surface dewpoints in the 5-10 C range, and a strong dry intrusion is approaching from the southwest along the front towards New Brunswick. The 0-6 km shear near the frontal jet is about 90 kt, and the 0-3 km shear is near 50 kts, which given the low moisture may shear off any convection. Over Nova Scotia the moisture is a little better, and CAPE’s may approach 300 J/kg if the inversion breaks, but the fast upper flow is moving things along fast enough to reduce local rainfall rates. For Newfoundland moisture is higher, with precipitable water amounts near 30 mm, which may go higher later today. 0-6 km shear is in the 40-50 kt range, but will diminish from west to east as a southerly jet moves east along the south coast. As the trough moving across Nova Scotia approaches, there may be a second bout, again with high shear, but with a bit more moisture than for the Maritimes. In general, rainfall amounts should remain below warning levels unless there is training, and wind gusts should stay below warning levels due to relatively low CAPEs.
Regional Impacts
Newfoundland: A few non-severe thundershowers in the east tapering off this afternoon. In the west a second batch of thundershowers beginning late this afternoon into this evening and persisting into the overnight period.
Labrador: no impacts expected.
New Brunswick: Non-severe thunderstorms this afternoon into this evening.
Nova Scotia: Non-severe thunderstorms mainly along the Atlantic coast. These thunderstorms will move east across the province, and will pass east of the mainland this evening and for Cape Breton by Wednesday morning.
Prince Edward Island: Nothing severe expected.
Doug Mercer
Lead Meteorologist
Atlantic Storm Prediction Centre
Meteorological Service of Canada
45 Alderney Drive, Dartmouth
Nova Scotia, B2Y 2N6
Office: (902) 426-9200
Premier Météorologue
Centre de prévision des intempéries de la région de l'atlantique
Service météorologique du Canada
45 promenade Alderney, Dartmouth
Nouvelle-Écosse, B2Y 2N6
Bureau: (902) 426-9200
Cell: (902) 403-7951