Regional Impacts
Today:
NB: Risk of thunderstorms giving heavy downpours and gusty winds in the late afternoon.
NS: Slight risk of a thundershower across the spine in the afternoon.
PEI/NL/LAB: None
Tonight:
NB: Risk of thunderstorms giving heavy downpours and gusty winds in the evening.
NL: Slight risk of an embedded thunderstorm reaching western region by early morning.
Tomorrow:
NB: Risk of severe thunderstorms with heavy downpours and strong wind gusts.
NL: Risk of thundershowers with locally heavy downpours and strong wind gusts.
LAB/PEI/NS: None
Convective Discussion
The main threat of severe convection today will lie along and ahead of a trough that will moves east to southeastward from north shore Quebec towards the Gaspe Peninsula this afternoon. Organised thunderstorms are not as likely now to reach northern New Brunswick given the timing and position of this trough, but there is still ample deep moisture and daytime heating that anything that does develop will give heavy downpours with water loaded gust potential. Mixed CAPE values are expected to exceed 1000Jkg and with effective shear reaching 35-40kt in northern New Brunswick. This trough will track across the northern Gulf of St. Lawrence and towards Newfoundland by tomorrow morning.
Over Nova Scotia, sea breeze convergence and daytime heating may be enough for a pop-up shower or thundershower across the spine if convective temperatures can be reached. Any cells that do develop will be slow moving and capable of producing localized heavy downpours as cells drift to the southeast.
For tomorrow, the threat of severe convection increases for new Brunswick as a low pressure tracks northeastward over southeastern Quebec and toward Labrador by Friday and a cold front will track into New Brunswick early evening and through the remainder of the Maritimes overnight into Friday. High MLCAPE, deep 50kt layer shear and high precipitable water (50 mm) will aid in the potential for multicell lines or potential supercells. Meanwhile, the trough from today will impact parts of Newfoundland tomorrow, mostly off the northeast coast where sea breeze and daytime heating will aid in further lift. Heavy downpours are expected to be the main threat but with moderate deep layer shear, some organization into lines is possible.
Thunderstorm Outlook for TODAY
Thunderstorm Outlook for TONIGHT
Thunderstorm Outlook for TOMORROW
Roberta McArthur