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

Regional Impacts

Today:

NB: Chance of thunderstorms giving locally heavy rain and strong wind gusts.

NL: Slight risk on a thundershower over the northern Peninsula

NS/PEI/Labrador: None.

Tonight:

NB/Gulf waters: Chance of embedded thunderstorms.

NS/PEI/NL/Labrador: None.

Tomorrow:

None.

Convective Discussion

A deep upper trough over central Quebec with a surface low pressure system currently over northwestern New Brunswick with track eastward today across the northern Gulf of St. Lawrence and into the Labrador Sea tomorrow. Embedded thunderstorms have moved across northwestern New Brunswick this morning ahead of the low, and further convection may fire along the cold front, which will move across New Brunswick this afternoon and evening. Meanwhile, along the warm front there has been isolated strikes across northern Newfoundland and the risk will continue into the early afternoon. The air mass in the warm sector is quite humid with dew points exceeding 20C. With a stalled ridge across northern Quebec into Labrador, ahead of the low, rainfall amounts are expected to reach upwards of 70 mm.

Along the cold front, thunderstorms will trigger this afternoon into the evening across New Brunswick into the Gulf waters with heavy rainfall being the biggest threat with precipitable water reaching 45 mm. Mixed CAPE values across northern New Brunswick may reach 500 J/kg if we get some clearing, and with effective shear of 30 to 40 kt, some organization is possible into line segments capable of producing strong wind gusts. Storms will move fairly quickly towards the northeast under a 40 kt 700 mb flow. Some overnight convection may hold across eastern New Brunswick and over the Gulf before the threat weakens overnight and into tomorrow.

Tomorrow the low continues eastward into the Labrador Sea and a ridge moves into the Maritimes with no thunderstorms are expected at this time.

Thunderstorm Outlook for TODAY