Convective Discussion
A cold front will move across the Maritimes this afternoon and evening. A diffluent upper flow and dropping heights will favour the development of severe weather ahead and near the front. Cape values of 1000-1500 J/kg and uni-directional shear of 30-40 knots is being indicated by the 12z soundings. Skies are clearing and the fog patches lifting in the wake of last night’s rain system, so daytime heating to 25-28 degrees is very possible. CU/TCU/CB formation is expected to develop shortly after noon. This system gave numerous reports of wind damage through New England on Thursday so that is likely the biggest concern. Dcape values are indicating 90-100 km/h gusts. Hail and torrential downpours are also possible. The precipital water is 30-35 mm. The freezing level is near 12,000 feet but there is good Cape through the hail growth zone. Oddly enough the main upper jet is well ahead of the surface cold front so not sure if the dynamics from that will play a part or not.
Regional Impacts
Maritimes…
Thundershowers, torrential downpours, hail and strong wind gusts are possible today. Severe thunderstorm watches will be issued for the area denoted in yellow.
Newfoundland and Labrador…
Risk of thundershowers for western Newfoundland tonight.
Andy Firth