Convective Discussion
Convective weather is possible for parts of every province, but possible severe weather should be restricted to New Brunswick and offshore waters, mainly for the Southern Scotian Shelf. For New Brunswick the main threats are gusty winds and local downpours. For the Scotian Shelf heavier rainfall is likely and there is a chance if significant gusts for southernmost waters.
Technical discussion
For New Brunswick there is a trough approaching from the northwest with good insolation near it. While moisture aloft is low, and precipitable water is only about 25 mm, there is fairly good surface moisture. There is moderate straight line shear near 35 kts. If and when cells initiate, this should give showers that might reach warning criteria, and downdrafts, especially as the trough should be an organising feature. Conditions should improve towards evening as the insolation dies away. For Nova Scotia expect continued locally heavy showers. Downdrafts will be inhibited by a near surface inversion.
For the Scotian shelf There is a possibility of downdrafts over southern waters, which may become significant. There’s also precipitable water amounts near 40 mm, which may give significant downpours.
For Newfoundland the profiles are too stable for surface initiation. There may be isolated elevated cells ahead of the trough approaching from the west, combined with some uplift along the south coast.
For Labrador the main likelihood is for the west. Insolation looks good, and there is a trough moving through to enhance convergence. I tried some higher temperatures for La Grande 4 and Goose Bay, and they only give CAPEs to 100-200 J/kg. If cells appear, weak dry microburst are possible.
Regional Impacts
New Brunswick: Local heavy downpours and gusty winds, gradually diminishing by evening.
Nova Scotia: Thundershowers, and occasional gusty winds
Prince Edward Island: Thundershowers.
Newfoundland: Chance of embedded elevated convection.
Labrador: Thundershowers with gusty winds possible, especially in western Labrador.
Doug Mercer