If that wasn't enough of a concern, as you'd expect with this air mass like this, severe weather is also a threat throughout the entire weekend. There is a lot of uncertainty tied to these storms, however; storms that form late in the day in Wisconsin/Michigan will make their way into the Ontario area in the early morning hours nearly every day of the severe threat. Whether they survive long enough to reach Ontario, make it into Ontario and take away some of the instability needed for Ontario storms to becoming explosive, or become explosive themselves, will have a influence on what Ontario will see this weekend. In addition, there's plenty of model disagreement; both in solutions per model, and run-to-run consistency. I'll break down the environment the storms will head into, however.
Severe Threat Analysis- Friday
|Near Chatham, Ontario. 18z|
In general, this means that the best speed/directional shear will not lie over the strongest areas of instability. Storms are likely to be strong due to the extreme instability, but more pulse style in nature; as opposed to discrete, long track supercells. This doesn't mean supercells can't/won't form (especially if one forms further north of the Kitchener/Waterloo region), but the further south in Ontario you go, the less shear storms will have to work with to reach max intensity.
I do think, with the extreme instability the area is due to see, that there's a chance that storms that do fire (especially along lake breeze boundaries due to lack of strong trigger) will upscale quickly (merge and continue to explode along the boundary). The entire 401 corridor should be paying attention to the possibility of torrential rain, hail, and damaging winds. It could get quite messy. An isolated tornado can't be ruled out if storms can avoid hitting each other and merging quickly, and can do so before running into Lake Erie.
If chasing (I'll likely be out), I think the safest bet to see storms will be from the Grand Bend area and south to Windsor/Chatham. That said, there is absolutely a chance that storms could fire along the 401 corridor, and I'll bet that the chances of it increase the longer that storms don't fire throughout the day, or if the air mass isn't influenced by early convection, but that's a morning observation. Some runs even had stronger storms entering the Hamilton/Burlington area by 18z. We'll see about that tomorrow. If that lake breeze boundary gets to set up to prominence, or the Lake Huron/Erie breezes collide with this brutal air mass, storms will explode to life. As discussed, there's a lot to determine first before that may/may not become a reality.
Photography wise, I'll see what I get to work with. If the relatively weak deep layer shear is what verifies, I can see these storms being VERY high precip style, which means structure and lightning may be problematic to get. If a tornado does form, it'll likely be rain wrapped, so if you're driving around the storms as they fire, think twice before driving into them.
Either way, stay cool, drink lots of water, and be on alert for some potentially strong storms this weekend.
Update Verdict (1:30 am Saturday morning):
I wish I took more screenshots of the radar while out chasing to prove my points, but I was driving around an awful lot and it slipped my mind. Ideally I'll pay more attention for future blogs.
CAMs did not do a good job of picking up ongoing storms heading into western Ontario in the am. They figured the storms would have been dying crossing Lake Huron, or would have already been dead by then, but with the extremely unstable air mass in place, they had too much fuel to die out completely. As a result, any storm energy north of the 401 area had most of their energy consumed by the early morning storms. Additionally, the outflow from these storms collided with a W-E lake breeze boundary already established by the Woodstock/Burlington area and we were off to the races.
Storms did fire along the 403/401 corridor; nearly exactly where I expected and mentioned above. I had them nearly form on top of me as I pushed west around 12:30 pm. I was tempted to stick around and see if a strong line of storms (with high winds and lots of lightning) formed, but I liked my original target a bit southwest of London.
Though I did allude to storms possibly being tornadic if they stood a chance at being discrete, truthfully, I did not expect the 2nd wave of storms to the NE of London to have so much rotation, or be as long lived; considering they were passing through an area that had already been hit by storms twice earlier in the day. I guess that's just a testament to how intense this air mass really is. It can make recover in very little time. I was in the notch of the first tornado warned storm that passed right over the city of London, but thankfully it didn't produce anything that caused any major issues. It became outflow dominant shortly after as it pushed SE towards Lake Erie. The 2nd wave of storms to the NE of London that tracked SE towards Woodstock were likely cells that spawned and followed the outflow boundary of the previously mentioned storm. Both had rotation on them for hours. I tracked the one cell further to the NE as it tracked towards Embro because I thought it had the best chance of staying discrete longer than the south one did. I'll be reviewing the pics and time lapse footage shortly.
Overall, I was content with my forecast. Definitely some room for improvement, but I did cover the areas that were hit today. I was just taken back with the timing and how quick the boundary layer recovered after the earlier storms. I did also think it would upscale faster than it did. It's a testament to this brutal, unstable, air mass.
Severe Threat Analysis- Saturday
|Very, very muggy|
Saturday (today) has a chance to have an EVEN MORE unstable air mass compared to Friday. Temperatures are expected to be a bit hotter, and dew points are expected to climb higher than Friday. Areas across southern Ontario may see temperature/dew point spreads of 92/80F- that is just unbelievable for Ontario. PWAT (precipitable water) values, in some areas, are about 2.5 inches (!!!).
|Just absurd amounts of MLCAPE|
So, not much changes for Saturday from Friday's forecast: the 401/403 corridor could get subjected to more high wind, torrential rain, and frequent lightning anywhere the lake breeze sets up. These volatile air masses make lake breeze boundaries good starting points; especially with a lack of a definitive trigger. Outflow boundaries from preexisting storms (if applicable) may also be factors. I still think early morning storms, whether they're modeled well, or horrifically (like Friday), may play a key role in shaping how Saturday unfolds. Storms could also be going up early again; early afternoon, as opposed to later in the day. There could be multiple rounds as well, especially as you go further southwest.
|London area, 18z|
Stay cool, stay hydrated and stay weather aware tomorrow. For those that loathe this kind of air mass, relief is on the way on Sunday.
Model consensus in the morning has shown quite a bit of change. They've been showing a nasty line of storms heading into Ontario along eastern Lake Huron around 00z instead of having semi-discrete storms that the previous 00z runs had shown, which would have been similar to yesterday. The expectation is that the weak cap will hold with little to no triggers (especially as no storms came through earlier in the day laying down outflow boundaries). If this were to be the case, brutal rain and very strong winds will be the primary threats for as long as the bow echo tracks southeast. This can, and likely will, include the area mentioned in the forecast above, and anywhere from Guelph, Hamilton, Burlington and south.