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

Regional Impacts

Today:

LAB: Risk of isolated thunderstorms over west LAB: Risk of isolated thunderstorms over southern Labrador.ern Labrador giving locally heavy downpours, strong wind gust and small hail.

NB: Risk of an isolated thunderstorm over extreme northwestern NB.

NS/PEI/NL: No thunderstorms forecast.

Tonight:

LAB: Risk of isolated thunderstorms over southwestern Labrador.

NB: Risk of an isolated thunderstorm over extreme northwestern NB.

NS/PEI/NL: No thunderstorms forecast.

Tomorrow:

NB: Risk of isolated thunderstorms giving locally heavy downpours and strong wind gusts.

NS: Risk of embedded thunderstorms giving locally heavy downpours.

LAB: Risk of isolated thunderstorms over southern Labrador.

NL:PEI: No thunderstorms forecast.

Convective Discussion

As a low pressure system over James Bay remains stationary, a warm front is moving across southern Labrador this morning with a cold front extending from western Labrador southwest towards the St. Lawrence River. The cold front this afternoon will trigger some thunderstorms across central Quebec and towards western Labrador by late afternoon or early evening. With CAPE values reaching 500 J/kg and increasing effective shear of 30kt, some thunderstorms may organize into multicells or lines prior to reaching. With freezing levels at around 10,000 ft and sufficient lift, small hail is also possible. Convection is expected to remain mainly west of New Brunswick today but may graze parts of western Madawaska and Restigouche counties.

Tomorrow, the front stalls over western New Brunswick while a low pressure system is expected to form off Cape Hatteras later today and move northeast towards Nova Scotia tomorrow. High rainfall amounts and embedded thunderstorms are possible mainly over coastal Nova Scotia and southern marine waters leading to potential locally heavy rainfall as precipitable water increases to more than 50 mm. The cold front will continue to spark thunderstorms for the afternoon in northwestern New Brunswick. CAPE values may only reach 250 but there is moderate bulk shear and increasing precipitable water so strong winds and heavy downpours are possible. A trough line may also spark a few embedded thunderstorms across southern Labrador as that tracks slowly northward.

Thunderstorm Outlook for Today