Regional Impacts
Today
NB: risk of a severe thunderstorm producing strong winds, hail and torrential rainfall this afternoon and evening.
Western Lab/PEI: scattered thunderstorms possible later today giving gusty winds, small hail and torrential downpours.
Tonight
Western NL/NB/PEI/western Lab: scattered thunderstorms possible giving mainly torrential downpours.
Saturday
Central NL: scattered thunderstorms possible in the afternoon and evening giving gusty winds, small hail and torrential downpours.
Convective Discussion
The main area of focus today will be across parts of NB as a short wave trough slowly approaches from the southern Quebec area. The timing of this feature will be important to maximize the full extent of day time heating. However, the dynamics later today are really good, so any storms that form and move into the region could last for a number of hours. The 12Z KCAR tephi has 2 strong warm noses above the surface, but does show close to 50 knots of mean shear from the surface to 6 km. it’s likely the Maniwaki profile further upstream would be more representative of the air mass that will be approaching NB later this afternoon. Adjusting for a surface temperature of 28-29 yields over 1000 CAPE. Much like the KCAR sounding the wind shear is high. And there is no lack of low level moisture as the Tds are in the high teens. Once the surface front/500 mb short wave makes its way in numerous thunderstorms will form in southern QB/northern ME, and will be monitored as they get close to NB. Based on current SAT imagery the timing for the potential severe storms will be later this afternoon and into the evening hours. As already mentioned, the dynamics appear good so even with the sun setting individual cells could last well into the night. Elsewhere some scattered thunderstorm possible for western Labrador and a portion of the Maritimes that is further downstream from the more buoyant atmosphere.
Nighttime activity is likely across western NL and a portion of the Maritimes as some of the cells that develop today maintain themselves and continue moving generally eastward (aided with cloud top cooling). The main concern would be torrential downpours at this time.
The same short wave could give a strong storm or 2 across central NL Saturday.
Thunderstorm Outlook for Today
Thunderstorm Outlook for Tonight and Saturday morning
Thunderstorm Outlook for Saturday
Jeremy