Thunderstorm Outlook for Day 1
Regional Impacts
New Brunswick: Near-severe thunderstorms possible late this afternoon and evening mainly over northwestern regions giving localised heavy rainfall (20-30 mm/hr), moderate to strong wind gusts (80 km/hr) and small hail (<2 cm).
Labrador: Isolated non-severe thunderstorms over southern parts of the region early this afternoon and evening.
Convective Discussion
An upper level low over western Quebec will slowly move northeastward today. A weak cold front currently over southern Quebec will move over Maine and into western New Brunswick this evening. Meanwhile a broad warm front extends into southern Labrador. Convection has been ongoing along both features this morning. Embedded convection may continue into the early afternoon over southern and eastern Labrador.
Ahead and along the cold front extending into southern Quebec and western Maine, organized convection is expected which may continue into western New Brunswick in the early evening and overnight period. The main inhibitors for now will depend on the current cloud deck over Maine and western New Brunswick which is taking a while to burn off. The lapse rates over the area are also not ideal as the 500mb cold trough remains back over Ontario and there is not much further destabilization expected in the upper levels. However, there is ample moisture available with dew points reaching 20C. The 12Z Caribou sounding shows quite a warm nose around 900 mb and that cap is expected to be broken once the cloud clears. It also has a decent dry layer from 500-700mb, indicating a risk for strong downdraft gusts. The 0-6 km shear has increased to 23 KT with Should things align, there is the risk for convection to organize into lines which could make their way into northwestern New Brunswick this evening. Frequent lightning, locally heavy downpours and strong wind gusts are the main risks.
Thunderstorm Outlook for Day 2
The upper low somewhat stall over central Quebec tomorrow. The threat for any severe convection diminishes. Only daytime heating pop up TCUs in showers with a slight risk of a CB seems likely over New Brunswick and Newfoundland with some embedded convection over western Labrador where the warm frontal feature is stalled.
