Regional Impacts
Today
LAB: Chance of some scattered thunderstorms over western Labrador today capable of producing strong wind gusts and heavy downpours.
NB: Slight chance of an isolated thundershower over extreme northwestern NB this evening.
NL: Slight chance of an elevated thundershower later today over western Newfoundland.
NS/PEI: None.
Tonight
NB: Chance for some elevated thundershowers over northern NB overnight into tomorrow morning capable of producing some heavy downpours.
NS/PEI/NL/LAB: None.
Tomorrow
NB/NS/PEI: Chance for some scattered thunderstorms over the central Maritimes in the afternoon capable of producing strong wind gusts, small hail, and heavy downpours.
LAB: Chance for some scattered thundershowers over southeastern Labrador tomorrow capable of producing some strong wind gusts and heavy downpours.
NL: Slight chance of an isolated thundershower over western Newfoundland late in the day.
Convective Discussion…
This morning, an upper low sits over western Labrador with a trough extending south into western Newfoundland, which will very slowly move northeast today to lie over the Labrador Sea by tomorrow afternoon. Behind this feature, a weak ridge is beginning to erode as it moves into the Maritimes due to an amplifying shortwave currently traversing the eastern Ontario and southern Quebec border. The upper low over Labrador will be the main driver for convection today in Atlantic Canada. Some clearing is evident over southwestern Labrador this morning, which should allow MLCAPE values to rise near 500 to 750 J/kg. There is however a lack of wind shear today over the region, with the main jet well south of the main risk area. This will likely lead to a short life span of any storms that fire today, and are not expected to reach severe criteria. The main hazards with any storms here will be some strong wind gusts and brief heavy downpours. Some Elevated thundershowers are also possible along the trough extending into western Newfoundland today. There also exists the small risk of an isolated thundershower over northwestern New Brunswick as well, however the lack of a trigger will likely keep any storms from firing here until later this evening.
Tonight, the aforementioned shortwave over eastern Ontario will approach western New Brunswick. With a strong 500 mb jet extending from southern Ontario through the southern Maritimes, convection is expected to maintain itself overnight as it moves in from Maine. Some locally heavy downpours will be possible overnight and into tomorrow morning in northern New Brunswick. By tomorrow afternoon, a low is forecast to spin up over central New Brunswick, with a warm front extending across the Gulf of St. Lawrence into southwestern Newfoundland. Some elevated thundershowers will be possible along the warm front, but the higher potential for thunderstorms will be in the warm sector over PEI, southeast New Brunswick, and western Nova Scotia. Here, given enough clearing before the cold front pushes through, MLCAPE values could rise upwards of 1000 J/kg. In combination with the strong jet over the region aiding in 30 to 40 knots of effective shear, some organized thunderstorms will be possible tomorrow afternoon that could possibly become severe given enough instability builds. PWATs are forecast to rise near 40 mm over the area of interest tomorrow which could lead to some locally heavy downpours, in addition to the potential for some strong wind gusts and small hail. Over southeastern Labrador, some scattered thundershowers could develop in the afternoon along the lingering trough extending down from the Labrador Sea. Once again, shear over this area is limited, so storms will not be very long-lived, but some brief strong winds gusts and locally heavy downpours area possible.
Thunderstorm Outlook for Today
Thunderstorm Outlook for Tonight
Thunderstorm Outlook for Tomorrow
Forecaster: Copp