Atlantic Canada Weather Blog: Convective Outlook Valid for Today, Tonight and Tomorrow

Regional Impacts

Today

NL/LAB… Isolated thundershowers with be locally heavy downpours of 10 to 20 mm/h and small hail of 1 cm or less. There is also the possibility of cold core funnels.

Tomorrow

NB/LAB…Isolated thundershowers giving locally heavy downpours of 10 to 20 mm/h.

Convective Discussion

A rather cold upper low continues eastward this morning over Newfoundland and into the Labrador Sea with a risk of some isolated thundershowers in northern and central Newfoundland and southeastern Labrador today. This area has a history of waterspouts over the Gulf of St. Lawrence and with continued cold air aloft, relatively warm surface land and water and topographic influences will aid in the potential of cold air funnels today over Newfoundland as this low continues eastward. With MLCAPE values around 800 J/kg, and weakening strait line bulk shear of 15KT, any thundershowers that develop are unlikely to become severe. Nonetheless, some brief heavy downpours of 10 to 20 mm/h will be possible and with lower freezing levels given the cold air aloft, there is a risk of small hail.

Another weak low is expected to move towards western New Brunswick and Labrador from Quebec tomorrow. Daytime heating and some instability will allow for pop-up convection ahead and near the centre of this low is where the risk of thunderstorms will be. There is little shear but moderate precipitable water so some locally heavy downpours are possible.

Thunderstorm Outlook for Today