Atlantic Canada Weather Blog: Convective Outlook Valid for Today, Tonight and Tomorrow

Regional Impacts

Today: Organized thunderstorms today across the SErn marine district, approaching the Nfld coastline early this afternoon. Lightning is the main hazard. An isolated cell or 2 may also pop up this evening in western Labrador and the Edmundston valley area of NWrn NB. A quick 5-10mm of rain could fall.

Tonight: No thunderstorms forecast in ATL Canada.

Tuesday: Late-day thunderstorms are forecast, with the progression of a destabilizing trof out of the Great Lakes region of Ontario. The timing of this trof is quite slow. The main hazards would be gusty winds ahead of the system and pockets of moderate rain. Rainfall rates are forecast to exceed 40 mm/h in the tri-counties area of NS *if* the system develops as models suggest.

Wednesday: Atmospheric conditions remain unstable, so afternoon storms are possible across Labrador, NB, NS, and portions of PEI with daytime heating, and relatively high humidity.

Convective Discussion

The first forcing at play is pulling out of the eastern marine region this afternoon. Mid-levels behind this feature on this morning’s soundings are prohibitively dry. However, Caribou is expected to moisten at 700 throughout the afternoon and as such could produce enough lift late day to spark a cell or 2. They will remain non-severe in nature. The regime tomorrow is somewhat more complex. Another trof is cutting across the Great Lakes and will de-stabilize the now moistened (and near heat warning) Maritimes environment. This will lead to both a wind gust hazard and moderate rainfall hazard on Day 2. If the total energy can be realized before sunset, some cells could approach severe limits. This is being closely monitored as many factors have to line up just right. The Day 3 outlook remains unstable across much of the Maritimes and Labrador with humid sfc conditions and cool air aloft from a developing upper low. This will create pockets of moderate shear with organized convection developing in the afternoon.

Thunderstorm Outlook for Today