The same system that has been wreaking havoc on the southern Gulf states will trek its way into Ontario. A strong 500 mb and 700 mb deformation zone will certainly enhance the precip in the northern portions of the province hence the large amounts of precip in the forecast. Current models show the occlusion holding off a little longer than previously forecast allowing a little more warm air to reach SW Ontario. Current Theta-E trend for SW Ontario shows a chance of some embedded thundershowers along and south of a line from Niagara to Sarnia with Windsor and Sarnia showing the better chance. The lakes will choke off most of the surface based CAPE but current trends show about 250-500 J/kg of elevated CAPE. I know, I'm really trying to squeeze a lot out of a weak set up.

Clearly the best action will be in the MDT Risk in the Carolina states where great Jet dynamics and strong diffluence in the vicinity of the front will make for a great set up for severe storms. Dew points looking to be into the mid to upper 60's (Fahrenheit) and CAPE in the 1500-2000 J/KG should make for an active day once again.