Today, severe thunderstorms in southern Ontario produced funnel clouds, large quantities of hail up to at least dime size, damaging winds that knocked out power to thousands near Oshawa, and even flash flooding.
Parameters similar to those present in S ON today will be present farther north and east starting late tomorrow morning: steep mid-level lapse rates over 7 C/km will favour updraft development and hail growth; WBZ heights under 2 km; over 1500 j/kg of SBCAPE locally; the passage of a shortwave trough and 0-6 km bulk shear over 20 kt will support some moderately organized storms that will likely produce isolated damaging winds and marginally large hail.
Significant mid-level dryness indicates damaging wind potential at 11 am on the 18Z 12K NAM. Storms should initiate around that timeframe as substantial CAPE should be in place by then.
Cover image is in the public domain