Thunderstorm Outlook for Day 1
Regional Impacts
New Brunswick: Possibility of non-severe thundershowers in the northeast if the thick cloud there burns off this afternoon. Possibility of Severe thundertorms in the extreme southwest if the cloud deck moves away or burns off, with high wind the largest risk, followed by heavy downpours.
Newfoundland: thunderstorms beginning this afternoon with possible heavy downpours, especially with the slow movement of the cells.
Convective Discussion
For Newfoundland: there’s a low of the coast of Labrador from 250 mb down, with some upper dynamic support with PVA approaching western Newfoundland. There’s some good moisture with dewpoints of up to 17 C and PWATs near 24 mm, with most of it below 850 mb, Shear and storm motion is relatively low, suggesting plenty of time for rain to accumulate, and mean layer CAPEs suggest possibly reaching or exceeding 500 J/kg near and west of Gander, if they can get some clearing. Small hail is also possible, with freezing levels around 10-11,000 ft.
For New Brunswick: there are some good ingredients, especially in the far southwest, but the big inhibitor is cloudiness. The most likely place for convection is in the northeast, where things may start clearing this afternoon, but with non-severe cells likely. The general ingredients are near 50 kts of shear, PWATs in the 30-45 mm range, with surface dewpoints near 19 C and 850 dewpoints near 13 C moving in from the west. If things clear in the north, CAPEs could reach 200-500 J/kg. Gusty winds and local heavy downpours are the main threats, but the cells should move fast enough to limit therainfall from any given cell.
For the southwest the main risk would be wind gusts possibly reaching warning level, followed by local heavy downpours. Again, this is assuming some surface insolation this afternoon.
Thunderstorm Outlook for Day 2
