Regional Impacts
Today: Organized strong to severe thunderstorms across much of New Brunswick this afternoon. Main hazards are strong wind gusts, large hail, and heavy downpours. Also the chance for some isolated thundershowers over central Newfoundland.
Tonight: Elevated thundershowers with locally heavy downpours possible over central Atlantic Canada tonight.
Tomorrow: Risk of scattered thundershowers with some strong wind gusts and locally heavy downpours over central Atlantic Canada tomorrow.
Convective Discussion…
A potent day is in store for much of New Brunswick today as an upper low spins into the region. A very unstable airmass in combination with an approaching cold front has triggered some strong to severe thunderstorms this morning along the St. Lawrence river valley. This front will move east, reaching western New Brunswick early this afternoon. The 12Z Caribou sounding from this morning indicated the potential for upwards of 2000 J/kg of MLCAPE given sufficient surface heating, with some fairly steep lapse rates due to the cold upper low. Moderate bulk wind shear of around 35 to 45 knots will be conducive for organized thunderstorms to continue through the afternoon and into this evening. Shear remains fairly linear, as such the main storm mode is expected to be multicellular, though an isolated supercell is possible early on in the afternoon. Dry mid-levels will help contribute to hail growth this afternoon, which could reach up to 2 cm in size.
Elsewhere, a very slowly moving frontal boundary off the Atlantic coast of Nova Scotia has been triggering some isolated thundershowers overnight, aided by a moderate 500 mb jet. Later this afternoon, as the left exit to this jet reaches Newfoundland, a few isolated thundershowers may trigger over southwestern portions of the province and progress northeast later this afternoon. Modest MLCAPE values of 500 to 1000 J/kg should be enough for some of these thundershowers to develop, but weaker bulk shears will keep anything from getting too organized. As such, the main hazards with these storms will be locally heavy downpours.
Thunderstorm Outlook for Today
Thunderstorm Outlook for Tonight
Thunderstorm Outlook for Tomorrow
Forecaster: Copp