Regional Impacts
NS… Scattered thunderstorms today across southern Nova Scotia, with torrential downpours of 30 to 50 mm/h.
NB… Isolated thunderstorms possible this afternoon across northwestern New Brunswick with strong wind gusts and heavy downpours of 15 to 25 mm/h.
PEI… Isolated thunderstorm possible early this afternoon with heavy downpours of 15 to 25 mm/h.
NL… Isolated thunderstorms possible this afternoon across southern Labrador with heavy downpours of 15 to 25 mm/h.
Convective Discussion…
A cold front sweeping across the Maritimes is triggering thunderstorms across the region this morning, with this expected to continue into tonight as the front moves east. PWATs of 52 mm from the 12Z Yarmouth sounding indicate an extremely moist atmosphere ahead of the main front. An area of tropical moisture sitting off Cape Hatteras is being pumped north into the Gulf of Maine by a strong ridge over the southern Atlantic. A line of thunderstorms has developed along this stream of moisture this morning, and have already begun moving onshore into southwestern Nova Scotia. These storms will likely continue to move north and east as the day progresses, reaching the eastern shores of Nova Scotia tonight. Current guidance suggest the heaviest convection will remain along the Atlantic coast, however it is possible for some thunderstorms to continue further inland. Due to the high amount of moisture available today, the main threats with these storms will be torrential downpours of 25 to 50 mm/h, which will continue overnight along the Eastern Shore. Localized flooding will be possible with heavy showers and thunderstorms today.
In addition, some isolated thunderstorms are also possible over parts of New Brunswick and southern Labrador this afternoon closer to the upper low. Clearing skies here will allow SBCAPE to build up over 1000 J/kg by this afternoon and bulk shear is forecast to be extremely high but linear; upwards of 60 kts. Due to the high shear, it is possible that storms may struggle to get organized, however strong wind gusts and heavy rain are possible with any storms that do fire.
Thunderstorm Outlook for Today
Thunderstorm Outlook for Tonight
Thunderstorm Outlook for Tomorrow
Copp