Favourable parameters will also be present on Wednesday, but due to a capping inversion, thunderstorms will likely stay well north of the Ottawa Valley and only affect central Quebec and northern Ontario; thus, Ottawa and Montreal will be guaranteed a dry, sunny day.

However, heading into Thursday, temperatures will quickly warm up from lows in the low 20s to near 30 C. Dewpoint values should be at least 18 C across the region, resulting in over 2500 j/kg of SBCAPE. Strong bulk shear should exist in all columns, resulting in a threat for various types of severe weather.

Fast storm motion with H85 winds 40-50 kt and PWATs up to 1.3″ will reduce the potential for prolonged torrential rainfall (e.g. more than 10 minutes long) whilst those attributes combined with at least 700 j/kg of DCAPE should result in widespread damaging wind gusts in thunderstorms. Large hailstones more than 3 cm in diameter are possible with low WBZs just under 3 km AGL.

Supercells may form due to high 0-3 km helicity values of over 150-200 m2/s2 although they will likely become squall lines with possible bowing segments due to a nearly unidirectional wind profile.

More information to follow.

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