Thunderstorm Outlook for Day 1
Rain with heavier convective downpours for the Atlantic Coast of Nova Scotia, with isolated lightning and some gusty winds. A weak area of convergence may spark up some cells for southwestern Labrador.
Convective Discussion
The main threat for today, and especially for tomorrow, is due to the influence of the remnants of Henri as it approaches and then moves through the Maritimes. Henri is a vertically stacked system up to 250 mb, within a vertically stacked trough, again up to 250 mb. There’s a frontal trough extending south then southwest of the low, and it is approaching the western Maritimes today. Moisture is good with near 22 mm dewpoints at the surface extending above 850 mb. PWATs are up to 50 mm. Also, east of the system there is a fre-frontal band with a low level jet extending up to 500 mb. The tephis show a roughly moist adiabatic profile ahead of the system, so not a lot of CAPE (~ 300-600 j/kg), with deep layer shear less than 25 kts. So basically local heavy downpours, some gusty winds, and maybe some lightning.
Highest rainfall amounts are likely for tonight into tomorrow. Late today into this evening it will start over the Atlantic Coast of Nova Scotia, then spread north.
Thunderstorm Outlook for Day 2
Basically the same story with the rainfall propagation east. The main system will be moving into New Brunswick, with some likelihood for isolated cells for the Long Range Mountains of Newfoundland.
