Severe thunderstorm warnings are currently in effect for discrete supercells in eastern Ontario. With only 1000 j/kg MUCAPE, 40 kt of effective shear, and KIs near 25, I wasn’t very sure of the severity and coverage of today’s storms which is why there was no write-up.

As for tomorrow’s threat, low-level moisture should be copious, allowing for greater convective coverage. CAPE should be slightly higher, in the 1500-2000 j/kg range, which should make for slightly weaker bulk shear near 25-30 kt. Veering winds from SSE at the surface to WSW at H5 may cause some storms to produce weak rotation. Speaking of H5, temperatures at that level should be around -14 C presenting us with a favourable environment for large hail.

Finally, significant mid-level dryness will be present ahead of convection, enhancing downdrafts and damaging wind gusts, as shown by the 18Z NAM for 2 pm tomorrow:


For Saturday, rinse and repeat.