Hot, humid airmass in place for southern Ontario over the next few days will bring a persistent risk of afternoon thunderstorms for the next few days. But this discussion I will focus on today just to keep things brief. Morning analysis below shows that the warm front is pushed into central/eastern ON and had allowed moisture latent airmass to surge into southern ON, which is further reinforced by current theta-e meso analysis. Note that this front is expected to stall out there for the next few days as well.

There is some high cloud and a few isolated showers to deal with this morning, which should gradually break up some through the morning hours which should lead to suitable heating through the day allowing for maximum destabilization through this afternoon. 06Z NAM is currently forecasting axis if 500-3000 J/Kg from the southern Muskokas to Windsorn by 2:00 pm this afternoon, but GEM is really underplaying the instability. Given the strong Theta-e riidge pushing in with the higher dew points, I think GEM may not be resolving CAPE well this i don't think instability will be an issue today however; the issue today will be the weak flow aloft and little CAP. I don’t think the lack of CAP will be much issue though since there are no real triggers except for the LB boundaries it will just be a matter of when the boundaries will decide to fire off. Flow aloft will be another cause for issue, with only roughly 15-30 kts of 500 mb flow, storms will have very little divergence and poor venting which will likely result into storms chocking off their own inflow and multiple outflow boundaries which can either enhance low level shear and aid in triggering more convection.

As briefly mentioned above main triggers for today will be mainly lake breeze fronts pushing inland, but will point out that the GEM is forecasting a little shortwave trough which could aid to reinforce the environment mainly for southern Ontario. Current indications are that convection could initiate as early as 2:00 pm due to the GEM short wave, but may be able to hold off until the 4-5 pm time frame. Thus the risk area will be the usual lake breeze convergence zone from Barrie to London, and narrow corridor from London to Windsor but lake modified air may push far enough inland here that storms may not be long lived. Storms should be able to sustain themselves long enough to push into the GTA regions, and Niagara is still kind of a question mark but at least a 30% chance there.

Little added note is that bulk shear is fairly low, but low level shear according to NAM bufkit profiles show a descent amount of sfc-850 low lever shear which could make for some good structure and a very small risk of a maybe a brief spin up, but nothing substantial in this department. As an example below I've shown the London forecast soundings and hodographs for 2, 5, and 8 pm which how graduall increas in low level shear. I only mention this risk because if CAPE values do get to forecast values, vertical velocities in updrafts may be enough to get good stretching within the column with suitable low level turning leading to a few brief spin ups.