Regional Impacts
Today:
NB…Some thunderstorms possibly severe for northern regions with locally heavy downpours of 25 mm/h, small hail and strong wind gusts.
NS…Heavy downpours in thunderstorms with rainfall rates of 25 to 50 mm/h over western and central regions.
LAB…Scattered thunderstorms over central and southeastern regions with locally heavy downpours, small hail and moderate wind gusts.
Sunday:
NB…Slight risk of severe thunderstorms with heavy downpours, strong wind gusts and small hail.
NS/PEI…Risk of thunderstorms with locally heavy downpours.
LAB…Slight risk over southeastern Labrador.
Convective Discussion
As an upper low stalls over eastern Hudson Bay, shortwaves will move through the region over the next several days. A broad trough continues over central and eastern Labrador and southwestward into northern New Brunswick today while a second shortwave moves across Nova Scotia and the southern marine waters today. Lightning has been consistent this morning over the Gulf of Maine with quite high rainfall rates. There is a risk of elevated convection and locally heavy downpours for western Nova Scotia and southern Maritimes waters as this wave continues eastward. Precipitable water over the region based on the YQI morning sounding is near 50 mm.
Convection could be organized over the Gaspe Peninsula southward into northern New Brunswick this afternoon given increasing moisture under a southwest flow in the afternoon with upwards of 1500 J/kg of MLCAPE, but upper dynamics are expected to be weak to moderate with bulk shear of 20 kt. Multicells are possible with brief strong wind gusts, locally heavy downpours and small hail being the main threats. Convection could be near severe over southern and central Labrador as well if the surface cap
For Sunday, a shortwave moves across eastern Newfoundland and Labrador while another wave begins to track into the Maritimes in the evening. Depending on cloud cover, widespread risks of thunderstorms are possible during the afternoon. There is ample energy with over 1200J/kg with the hot and humid air mass persisting over the region, but also an increase in dynamics with 30 to 40 of bulk shear with an approaching upper jet over central Quebec, but there will likely be a warm nose near the surface to overcome. For now central and southern New Brunswick may have the highest potential for reaching severe thunderstorm criteria.
Thunderstorm Outlook for Today
Thunderstorm Outlook for Tonight
Thunderstorm Outlook for Tomorrow
Roberta McArthur