Regional Impacts
Today
Labrador: advancing trof bringing in slightly better dynamics for taller and more organized thunderstorms. Gusty winds, small hail, and brief but heavy downpours are possible. This has already started over southern sections this AM.
NB: Thunderstorms are possible in the afternoon and evening as the cap is finally able to break in this airmass (mainly tied to geography). Small hail and heavy downpours are possible.
NS: Guidance is suggesting the cap will break in the afternoon for an isolated region along the “spine” and the South Shore. Brief, heavy downpours are possible. These cells will move south over the coastline/water late in the day. They are forecast to remain isolated.
Tonight
None expected over land areas.
Tomorrow
Labrador: repeat of dynamics from Friday but less moisture to work with over western areas.
NB: Scattered thunderstorms are possible again in the afternoon and evening. Southern sections look to be more airmass, and northern areas forced by an advancing trof. Details will be added on Saturday regarding these specifics.
NS/Bay of Fundy: Numerous scattered thunderstorms are expected along the E-W spine and northern areas of NS. The main hazards will be small hail and heavy downpours for areas under the cells.
Convective Discussion
The story for the Maritimes today continues to be the high heat and humidity. Dew points this morning are reaching 21 in places. This is fuel for convective weather, if the cap can break. It seems that it will across NB this afternoon, and isolated western parts of NS (using E townships of Quebec as an upstream reference from yesterday). These cells will bring brief heavy downpours. There is less forest fire smoke present in the mid levels of the atmosphere than yesterday, but it is not zero. Storms that fire today are largely expected to be terrain driven.
In Labrador, the organization is quite a bit better for multi-cells over southern sections, forced along the advancing circulation/trof. Formation is evident already on visible satellite. These cells could produce strong wind gusts, and small hail along with frequent lightning and heavy downpours. Northern areas of Labrador are only expected to see single cell or embedded convection similar to yesterday.
Tomorrow will bring a renewed and more broad convective risk to Atlantic Canada. With the high moisture and forcings approaching from the west acting to destabilize the airmass further, multiple areas of thunderstorms are expected – tied to geographic and synoptic triggers. The exact timing and locations will be clearer tomorrow morning on water vapour imagery, but it is important to note that if any cells persistently train over one area, quite a bit of rainfall could occur in a short amount of time. Pwats are expected to be very high.
Thunderstorm Outlook for Today
Thunderstorm Outlook for Tonight
Thunderstorm Outlook for Tomorrow
Forecaster: Tirone.