Regional Impacts
NS: Isolated thundershowers possible this afternoon across mainland NS, locally heavy downpours of 10-20 mm. Chance of an isolated thunderstorm over the Cape Breton Highlands early this afternoon; 1-2 cm hail, 70-90 km/h wind gusts, and locally heavy downpours of 25-50 mm.
NB: Isolated thundershowers possible today, locally heavy downpours of 10-20 mm.
PEI: Isolated thunderstorm possible over eastern PEI early this afternoon; 1-2 cm hail, 70-90 km/h wind gusts, and locally heavy downpours of 25-50 mm.
NL: Scattered thunderstorms possible through west-central NFLD today; 1-2 cm hail, 70-90 km/h wind gusts, and locally heavy downpours of 25-50 mm.
Convective Discussion…
A small but intense shortwave trough moving through the Maritimes this morning brings the chance for sever weather across the eastern gulf of St. Lawrence and west-central NFLD today. Models have been struggling to resolve the intensity of this trough, with some strong storms having already moved through PEI and Iles-de-la-Madeleine this morning. These storms have weakened slightly as they moved over cooler gulf waters, but may re-intensify as they approach Cape Breton and the western shores of NFLD early this afternoon. Upper dynamics will allow for sustained convection over west-central NFLD, with a 110 kt 250 mb jet over the region. Bulk shear of 30-40 kts and SBCAPE values in excess of 1000 J/kg provide an ample environment for severe weather potential with the incoming shortwave trough acting as the main trigger. These storms will move northeast into north-central NFLD by this evening. The main threats with these storms will be pea to dime size hail, strong wind gusts reaching 70-90 km/h, and locally heavy downpours of 25-30 mm per hour.
In addition, isolated pop-up thundershowers are possible across the Maritimes this afternoon. Due to a lack of upper support however, these storms are expected to have short life spans, with the main threat being brief heavy downpours.
Thunderstorm Outlook for Today
Thunderstorm Outlook for Tonight
Thunderstorm Outlook for Tomorrow
Copp