Regional Impacts
Today
NL: isolated thundershowers giving locally heavy downpours.
Tonight
No thunderstorms forecast.
Thursday
NB: scattered thundershowers with risk of lightning, heavy rain and strong winds.
Convective Discussion
An upper trough with a cut-off surface low pressure system will slowly weaken as it tracks northeastward over Newfoundland today. Any remaining convection today will be near the low centre where cooling aloft along with surface based heating will help provide instability for isolated thundershowers. With low CAPE values of 200-400 J/kg and not much bulk shear, the main threat will be enhancement to rainfall where precipitable water remains in the low 30s, however, low level winds will maintain quick movement of anything that develops.
An approaching hot and humid air mass moves into the Maritimes on Thursday. Ahead of an upper trough that will be moving through southern Quebec/New England during the day will trigger organized convection that will likely move into extreme northwestern New Brunswick later in the day. There looks to be ample energy with forecasted CAPE values of over 1000 J/kg with sufficient 0-6km shear as well as low level shear to support organized bowlines and possible supercells ahead of the trough. The uncertainty at the moment is the timing of this feature as it progresses into New Brunswick as instability will diminish into the evening/overnight period.
Thunderstorm Outlook for Day 1
Thunderstorm Outlook for Day 1 night/Day 2 morning
Thunderstorm Outlook for Day 2
