Day 2 Convective Outlook for Atlantic Canada Valid for July 14, 2018

Convective Discussion

Slight risk for convection later in the day Saturday over northwestern Labrador as a trough moves in from the west. Meanwhile a slow moving trough south of Nova Scotia may generate conditions favourable for thunderstorms over most southern waters of the maritime marine district and possibly into the Newfoundland’s southwestern Grand Banks.

Technical Discussion

An upper trough moving toward Labrador has a history of producing thunderstorms in its wake over northern Quebec. The timing for the passage of this feature over western Newfoundland is not that great and the risk for severe convection during the outlook period for western Labrador is low.  Over the southern Maritime Marine district similar instability remains and upper level triggered thunderstorms are possible with primary threats being wind gusts of 35 knots or slightly more if they form. Of course the mixing of these winds would be subject to the in-situ stability over the marine areas.

Regional Impacts

Newfoundland, Labrador, New Brunswick, PEI, Nova Scotia, and Labrador Marine: No severe convection expected.

Maritime and Newfoundland Marine: Slight risk of thunderstorms around the through over southern waters. Primary thunderstorm threats should they form would be wind gusts near gale force.

Marshall Hawkins

Day 1 Convective Outlook for Atlantic Canada Valid for July 13, 2018

Convective Discussion

No severe convection is expected across Atlantic Canada today with the exception of and increased risk for severe convection over  the southern Maritime  and Newfoundland marine districts.

Technical Discussion

Multiple capping inversions across the region resulting from an upper ridge to the west and a slow moving upper trough over the region will not provide conditions favourable for the development of severe convection over the majority of Atlantic Canada. For the southern Maritime/Newfoundland marine districts, persisting upper level divergence associated ahead of the upper trough will assist in the continued development of convection throughout the period. Aside from lightning,  the primary risks with these cells would be wind gusts near 35-40 knots. The threat of wind is the largest where water temperatures are warmest in the shaded area above.

Regional Impacts

New Brunswick, Nova Scotia, PEI, Newfoundland, Labrador: No severe convection expected.

Labrador Marine: No severe convection expected.

Maritime Marine/Newfoundland Marine: Thunderstorm risk is largest over the southern waters. Primary threat – wind gusts near or exceeding 35 knots (stability dependent w.r.t sea surface temperatures), otherwise, no severe convection expected.

Marshall Hawkins