Thunderstorm Outlook for Day 1
Regional Impacts
New Brunswick: Scattered thundershowers beginning by early to mid afternoon, with some heavy downpours and gusty winds.
Labrador: Isolated to scattered thundershowers with some gusty winds and brief heavy showers.
Convective Discussion
There’s a deep upper low over northern Hudson Bay , with a deep upper trough extending southeast over western Labrador into the eastern Gulf of St. Lawrence. There is also a deep upper thermal trough west of Labrador. Weak to moderate 250 and 500 jets have Right Exits near and north of the Gaspe Peninsula and all of this is slowly moving east. There is a reasonable chance for near severe thunderstorms for New Brunswick, with a slight chance for severe. Upper dynamic support is limited to the extreme north of the province, but there is healthy shear near 40 kts, moderate PWAT around 30-35 mm, but with no really significant amounts from the surface to 700 mb, then with some drying. The main mechanism will be daytime heating, and some extra moisture from low stratus over New Brunswick, and a surface trough from western Labrador to just northwest of New Brunswick along the St. Lawrence as a possible organising feature. The main impacts will be locally heavy downpours and some gusty winds. Significant hail is unlikely, with freezing levels near 115 to 145 hft for Caribou and Gray.
For Labrador TCus have started, associated with the trough over western Labrador, and some thundershowers should start soon. This and daytime heating are the triggers and organising features. PWAT is 15 mm near YYR and 30 near YWK, And shear is near 15 kts east and 25 west. The stability will inhibit things somewhat with a weak inversion from near 800 mb upwards. All this suggests the western cells will be a bit more intense. Maximum CAPEs should be near 250 J/kg. So the major impacts are some intense but brief showers, some gusty winds, and a slight chance for hail.
Thunderstorm Outlook for Day 2
For day two a deep upper ridge starts to move in, and upper dynamic support is minimal. However weak low level troughs approach western Labrador and the western Maritimes, and there’s a chance for some thundershowers, with a bit more support for New Brunswick with higher moisture, shear, and potential moderate CAPE.
