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

Regional Impacts

Today:

NS: Risk of embedded thundershowers early this afternoon with locally heavy downpours.

Tonight:

None.

Tomorrow:

None.

Tuesday:

NB/PEI: Risk of severe thunderstorms with locally heavy rainfall, small hail and strong wind gusts.

NS /NL: Risk of thundershowers giving local heavy downpours and strong wind gusts.

Convective Discussion

A short-wave trough is moving through the Maritimes today. Based off the 12Z Caribou sounding, the 500 mb temperatures would suggest that convection will remain capped as the rain moves through, although the band has produced some 10-15 mm/hr rainfall rates over northwestern New Brunswick this morning as precipitable water is in the mid 30s. These heavier showers are expected to diminish by the time the band moves into eastern Nova Scotia as the wave buts against the ridge of high pressure over Newfoundland. There have been a few strikes over the western Maritime marine waters this morning and the small threat of embedded thundershowers may continue into western Nova Scotia early this afternoon where they may be enough lift between 700 and 850mb to break the cap. A cold front will move southeastward across Labrador this afternoon and evening, but the 500 mb temperatures also will be a limiting factor in any convection that develops.

For tomorrow, the weakened trough keeps Newfoundland under cloud and showers for most of the day, while the Maritimes most of Labrador are under a ridge of high pressure. This ridge extends across most of the eastern US, with building heat and humidity into New Brunswick. A low pressure system over central Ontario moves into Central Quebec in the evening. An area of destabilization will move towards the Gaspe Peninsula and into northern New Brunswick later in the evening with the risk of a thunderstorm lingering into the overnight but given the timing, the risk of anything severe is limited.

For Tuesday, there is increasing heat and humidity for all the Maritimes with dewpoints into the low 20s. A cold front is expected to track across New Brunswick in the afternoon. The high surface temperatures combined with cooling in the mid-levels with the cold front along with decent CAPE and wind shear, will provide the potential for severe thunderstorms mainly for New Brunswick and Prince Edward Island. Details will become more clear in the coming day.

Thunderstorm Outlook for TODAY