A strong low-level jet will be present over S/E ON and S QC throughout the day tomorrow as temperatures warm into the lower 20s. However, CAPE should only be in the 250-500 j/kg range in most areas. Nonetheless, the combination of extreme shear (65-75 kt at H85; 90 kt at H5) and strong frontogenial forcing along a cold front will allow of the development of a powerful squall line with widespread wind gusts in excess of 90 km/h as shown here:141017

The line is expected to develop in SE MI or SW ON late tomorrow morning then move into SE QC early in the evening.

Little in the way of lightning is expected due to the marginal instability but the intense rainfall in low-topped squall lines will easily bring down the low-level jet to the surface as is typical of most cool-season squall lines.

Wind gusts on Lakes Erie, Huron and Ontario could exceed 120 km/h with the passage of the line.

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