Regional Impacts
Newfoundland: Isolated thundershowers for western Newfoundland stretching eastward during the evening across the Island.
Labrador: Slight risk for an isolated thundershower over southeastern coastal regions.
New Brunswick: Isolated non-severe thunderstorms today for southern and western regions.
Convective Discussion
A slow moving upper level low resides over eastern Labrador stretching into the Labrador Sea. Some convection may ignite near the low centre today over southeastern coastal areas of Labrador today. A trough extending from Anticosti southwest towards the eastern townships in Quebec will move eastward today to lie over western Newfoundland towards southern New Brunswick this evening.
Areas of western Newfoundland could see some enhanced dynamics with the left exit of an upper level jet, combined with an approaching 500mb cold pool to help destabilize the environment ahead of the trough for late this afternoon into the evening and overnight hours. There is not much moisture with around 15 mm of precipitable water but decent uni-directional shear of 35KT could maintain convection with CAPE values between 200 and 500 J/kg. Some cloud-top cooling could maintain what may develop as it moves over western Newfoundland towards the east overnight.
Due to the quite cool area aloft over the Gulf of St. Lawrence, and decent uni-directional shear, there could again be a very slight risk of a waterspout develop over areas of eastern Anticosti, Gulf-Port-Au-Port, and Northeast Gulf marine areas this afternoon and evening.
Areas of southern Maine extending into southwestern New Brunswick will benefit from some enhanced upper level dynamics being in the area of the right entrance of an upper-level jet. A cold 500mb trough extending over central Maine combined with some warming at 850mb will help to overall destabilize the atmosphere. The only issue is the amount of rain and cloud moving through the area this morning, prohibiting much in the way of surface-based heating and areas over northern New Brunswick will likely not be able to break the warm cap at 700mb. Precipitable water values of 25-30mm over Caribou would suggest that some decent downpours are possible, but with strong 0-6km shear at 55KT a relatively strong flow aloft, cells would not likely see high rainfall rates for long. CAPE values also remain fairly weak at less than 250 J/kg. Some drier air between 700 and 500mb could mean some medium to strong downdrafts are possible and this will be the main concern with convection that develops this afternoon.
Thunderstorm Outlook for Day 1
Thunderstorm Outlook for Day 2
