Regional Impacts
Today
New Brunswick: Isolated near-severe thunderstorms possible giving locally heavy downpours over central to northern regions.
Labrador: Isolated to scattered near-severe thunderstorms possible giving locally heavy downpours, strong wind gusts and small hail.
Newfoundland: Isolated non-severe thunderstorms possible giving locally heavy downpours.
Tonight
New Brunswick: Isolated non-severe thunderstorms giving locally heavy downpours.
Sunday
New Brunswick: Isolated non-severe thunderstorms possible giving locally heavy downpours over northwestern regions.
Labrador: Isolated non-severe thunderstorms possible giving locally heavy downpours over western regions.
Convective Discussion
The main threat of showers and thunderstorms will be over central to northern New Brunswick and southeastern Labrador under a hot and humid air mass today. Elevated convection this morning over northern New Brunswick is expected to clear with high temperature expected to exceed 30C. Some initiation is already occurring over the eastern Townships in Quebec and central Maine that will drift slowly northeastward into New Brunswick late this afternoon or this evening. Although there is ample potential again over New Brunswick with CAPE values above 1500 J/kg, dynamics are not as favourable as they were yesterday over New Brunswick but the precipitable water remains high and any convection that develops will be slow moving with weak 0-6km shear.
Convection over central Labrador will continue eastward under an upper level low today. The 12Z Goose Bay sounding indicated a strong capping inversion around 900mb but with a weak 850mb jet along with topographic lift and approaching 500mb thermal trough, some organization of storms is possible. With weak shear and high precipitable water near 40 mm, the main risk will be heavy downpours. There is a slight risk for a pop-up thundershower over the southwestern interior of Newfoundland this afternoon if daytime heating can break a capping inversion near 850mb.
For Sunday, an approaching short wave trough over central Quebec will track northward with instability increasing over western Labrador and northwestern New Brunswick.
Thunderstorm Outlook for Today
Thunderstorm Outlook for Tonight
Thunderstorm Outlook for Sunday
Forecaster: McArthur