Regional Impacts
Today:
None
Tonight:
NB/NS/PEI: Isolated thundershowers giving locally heavy downpours
NL&LAB: None
Saturday:
NB/NS/PEI: Scattered heavy downpours, especially into the evening hours. Strong wind gusts are also possible for western NB in the evening.
NL&LAB: None
Convective Discussion
Moisture from a frontal boundary advancing across central Quebec extending into central Labrador will combine with a short wave trough over New England which will push northeastward tonight into Saturday over the Maritimes. Some of this moisture has some tropical influence stemming from the remnants of Tropical Storm Hilary as it rounded a quasi-stationary ridge of high pressure over the central US. The upper levels are warm over Labrador today and given the current could cover, afternoon temperatures may not be high enough to break the cap. There could be a slight lightning risk, but regardless, some vigorous TCUs and isolated heavy downpours are expected today. Another ridge of high pressure over Newfoundland and southeastern Labrador will suppress any convection today.
As the southern trough moves into the Maritimes tonight and into Saturday, the risk of isolated thunderstorms increases. Precipitable water of 40-50mm will also spread into Nova Scotia and the Gulf of St. Lawrence. The trough over the Maritimes on Saturday will slow down as it gets blocked against the ridge east of Newfoundland. This will increase the threat of training showers or thunderstorms especially for Saturday night. Rainfall rates of 25 to 50 mm per hour are possible but there is uncertainty in the amount of lightning expected versus just tropical downpours which will make rainfall amounts highly variable. Meanwhile, the trough over central Quebec will shift southeastward into Maine tomorrow afternoon. Increasing CAPE and effective wind shear over that area could see some convection organize into lines and move into western New Brunswick by the evening.
Thunderstorm Outlook for Today
Thunderstorm Outlook for Tonight
Thunderstorm Outlook for Saturday
Forecaster: McArthur