Regional Impacts
Southern LAB: Scattered to frequent thunderstorms are expected this afternoon and evening giving strong wind gusts, small hail and heavy downpours.
Southern NB: Scattered thunderstorms possible later today, tonight and early Sunday morning giving heavy downpours. Isolated thunderstorms possible again Sunday afternoon/evening.
PEI: Scattered thunderstorms possible overnight tonight or early Sunday morning giving heavy downpours.
SWRN NL: Isolated thunderstorms possible Sunday morning giving heavy downpours.
NS: A very slight chance of a thunderstorm this afternoon/evening for some central locales giving heavy downpours.
Convective Discussion
The interesting area to watch today will be up in the Big Land, where a frontal trough (acting as the trigger) will give way to scattered to frequent thunderstorms this afternoon. Moisture is nothing to write home about, however the shear and instability is good. 12Z YYR sounding shows about 50 knots of westerly shear, as well as some fairly steep lapse rates in the mid-levels. That could lead to good vertical velocities and support small hail growth. Strong wind gusts of 70-80 km/h are possible. Pretty much all the activity will be confined to areas where there are no public forecasts. However, there is a possibility of a strong storm or 2 advecting towards southeastern communities later this afternoon and into this evening. The only caveat would be the enormous amount of smoke evident on visible SAT imagery. The current ongoing thunderstorm activity in the southeast will soon diminish.
A pre-frontal trough/short wave over the New England states will move into southwestern NB later today crossing the MRTMS tonight before weakening over southwestern NL Sunday morning. Although there is not much history of lightning, there are indications of development as the sun sets this evening leading to a nocturnal event for some areas. Locally heavy downpours are the threat if they form.
Lastly a slight chance of an afternoon/evening thunderstorm Sunday for a portion of southwestern NB. Again, heavy downpours seems to be the main threat at the moment.
Thunderstorm Outlook for today
Thunderstorm Outlook for tonight/Sunday morning
Thunderstorm Outlook for Sunday
Jeremy