Convective Discussion
· A frontal disturbance over Quebec may bring a few potentially severe thunderstorms to northwesternmost areas of New Brunswick late in the day-evening and night
· The same disturbance may trigger isolated thundershowers over parts of Labrador during the day
· Elsewhere, a quasi-stationary ridge will prevent any convection.
Technical Discussion
High pressure system continues to prevail over southern Maritimes and Newfoundland. A frontal disturbance west of the region is triggering elevated thunderstorms over southern Quebec and central Labrador this morning. The thermal ridge associated with this feature will slowly advance over NB today with un-modified SWEAT indices suggesting non-severe thunderstorms. However moisture content will continue to increase in response to a 25-30kt southwesterly low-level jet so that by the end of the day modified indices are indicating a potential for severe thunderstorms especially during the evening and night period. Precipitable water estimates from this morning sounding are already in the 40-50mm range in parts of the risk area (25-30mm over Labrador) resulting in a potential for bouts of heavy showers with amounts approaching warning thresholds.
Regional Impacts
Northwestern New Brunswick: Isolated thunderstorms possible during the evening and night. Heavy downpours are possible (25+mm).
Labrador: Isolated thunderstorms possible during the afternoon and early evening. Brief heavier showers and wind gusts to 70km/h are possible.
Jean-Marc