By the first signs of dawn with a blue tint to the sky, the Don River fully overtook the Parkway reclaiming its old flood basin

Pretty Impressive!

For reasons I'm not going to get into... I was stuck in the southbound DVP traffic with a bunch of other people. Now don't worry, when I took this photo I was stopped. In fact people were getting out of their cars and wandering about.

The Black Creek bursts over its banks flooding the roadway

A car is stalled and stranded after attempting to cross a flooded road

I wanted this to be a super low topped supercell and it sure had some spin but it was not going to do anything at only 10,000ft tall.

As warm air continued to run in from the south and push the storms outflow and other stuff north we had a lovely evening sky. Dave came across this wonderful view from the escarpment looking southeast.

The highest and lowest points in this image range from about 468 meters ASL were this photo was taken to the valley which is only about 100 meters ASL. On the distant horizon, if you could see Lake Ontario it would be about 74 meters ASL.

Here's the trip log, 365 km

This is the technical stuff I promised. You can see the real world cape is only marginal at less than 1000 j/kg and the storm would only top out at 8.5km or about 35,000 feet which is not very high considering that these storms usually hit 50,000 feet or more. Furthermore while the max UVV hit 44 m/s overall, surface based LI's are only -2 which in the grand scheme of things suggest sluggish upward motion. While this type of setup does not constitute cold core convection it's indicative of mini low topped supercells.

The real magic which made everything work was the storm relative helicity which saw good easterly and southeasterly low level and mid level inflow with winds veering aloft and allowing updrafts to tilt towards the north or northeast.

These are 30 minute radar cuts showing the mini supercell and it's evolution from grand Bend onward. I'm using the data in snow mode to exemplify the structure, the standard rain mode produces returns that are too soft/weak. You'll see a distinctive hook echo like structure near Mount Forest just as the storm was producing that beautiful wall cloud.

Despite a lack of energy but good storm relative shear, the storm for a brief time was perfectly positioned right along the 500mb jet nose allowing extremely good ventilation. Again, this would have been when the storm was producing the wall cloud near Mount Forest. Unfortunately as it continued to move northward it moves into less favorable low level winds. The storm was also riding along the edge of a 700mb moisture plume which was providing clear skies and strong daytime heating south of the storm cell. This allowed the southerly inflow to remain warm and moist at not only the surface but especially in the mid levels.

This is probably the tell tale sign of why the storm did not produce anything more than pretty clouds. One thing to note is that the SPC Meso Analysis always over estimates CAPE values so don't take the numbers at face value, just understand that there is more and less energy in certain places. The storm fired off the boundary wave pushing northeast from Michigan and was supported by the 700mb moisture plume seen previously, this is delineated using the yellow line. At the surface ahead of the wave a warm front was pushing north which is delineated by a pink line. The maximum shear values were attained directly along this front due to enhanced forcing at the surface. Initially models showed the storms to fire about 1 hour later than they actually did. What this meant is that the supercell entered the Mount Forest area at 4:30PM as opposed to 5:30PM and as a result the surface front which was lifting north was barely ahead of the storm. This meant that there was less available energy than forecast, it also put the storm in a position where it was riding and potentially lifting (becoming slightly elevated) as it rode north of the boundary on the 500mb jet nose and eventually fully outpaced the forward motion of the surface warm front. This explains why the storm was ingesting so much crap by the time it was closing in on Barrie, it was basically either sitting directly on or actually ahead of the surface front by that point. So ultimately the storm fired one hour too soon and did not have enough environmental energy or run time so to speak to spit out a funnel.

Last image, and maybe the most interesting, note the storms position relative to the supercell composite parameter and significant tornado parameter. This just goes to shore, severe weather and tornadoes can be highly localized due to localized parameters, this is especially true in places such as Southern Ontario where boundaries are often plentiful and play huge roles in the development of severe storms.

By 7:30AM it was already 18 degrees with a humidity of 94% making it feel like 20C with the humidex. Tower cumulus were already bubbling up in places as conditions only got hotter with the sun beating down.

Convection started going up early, two waves were forecast to move in from Michigan by both the Regional GEM and later the HRRR. Morning visible satellite images and even the radar data agreed well with the forecast showing both these waves very well in the visible satellite imagery. Also visible was a pre existing stationary boundary that was literally running right along highway 9 and eventually meeting with the Lake Ontario breeze. This boundary was in place since at least May 19th when weak storms fired off the leading edge and it was not washed out by the squall line May 20th since during the early morning hours of the 21st nocturnal convection fired along this same boundary. So by 12PM I was on the road and heading west towards Arthur to intercept the rapidly developing storms.

I rolled some video around Grand Valley. The sky was getting dark and it was hot out, damn hot! The air was super sticky and muggy, there was a fairly strong southerly flow and the day had that Oklahoma feel to it, the feeling you get just as your waiting for a supercell to come into view. Of course, this was no supercell and the skies looked ominous but it was not like I was expecting anything crazy, which is very different from Oklahoma! I guess, the anticipation is really the feeling I'm describing.

As I was just going to punch through the first storms, things were getting a little messy, there was a lot of convection going up ahead of the main storm cell I was interested in. My gut told me to stop driving and wait, but the radar was screaming at me to keep going west so I listened to the radar.

So yeah, it started to pour, not overly hard and there was no wind or anything so the rain was more of a visibility hindrance I found then anything to worry about.

Just as I was outside of Arthur I saw a green flow directly in front of my and then a wall of scud quickly rising as it was being pushed up by outflow. I was not nearing one of the first stronger cells in the cluster ahead of the main storm. When I drove into it, the rain hit like a wall! There was some wind in the 50km/h range but it looked more severe than it was due to the rain falling so hard and banding into sheets. I heard a few dings from pea sized hail.

I kept pushing and punched into the main storm I was interested in intercepting. Just as I started to get into the core the storm blew itself out. The winds began to really gust hitting about 63 km/h at times but that was it, the highest gust was actually 63.7 km/h with the average around 50 - 55 km/h. You can see how the rain was just howling up the road towards me but again, it was not severe. It just looked more intense than it really was.

Again, anytime things are rocking and rolling video always takes presidence over still photos. Maybe I just have this opinion because I'm actually a videographer by trade?

Yep, the rain was just rolling through the fields!

After getting my fill of video and outflow wind I decided to keep driving towards the storms southern flank. I was getting dinged by random pieces of pea sized hail and then I had a couple dime sized stones hit me but they were few and far between. It felt like it was taking me forever to reach the southern flank of the storm but then suddenly clearing appeared ahead and I could see the definite boundary coming into view.

Later in the evening back in Toronto, the squall line continued through the city dumping heavy rain and this unfortunate driver lost control after his vehicle hydroplaned through a T intersection and crashed down an embankment. Fortunately him nor his passengers were injured.

Not bad, 399 km

Here's the radar shot at 7PM EST showing where the meso scale outflow boundary (gustfront) actually lies relative to the precipitation. You can see the outflow is a good 40 - 50 km ahead of the actual precipitation, that's why things were so deceptive. Usually outflow does not lay that far ahead of the main body of the squall line and if it does, the squall line is usually moving along at 100+ km/h

As night turns to day slowly, the morning rays of sunshine reveal showers produced by elevated thunderstorms moving in along a warm front.

Here's a radar shot showing the first target storm as it tracked southeast from Shelburne. You can see it is the dominant storm cell in the line. At around this time I'm making my way east on the 407 to head north on the 404 for an intercept.

This was one of the few dominant storm cells approaching me from the west. I raced north along highway 404 and stopped on Stouffville Rd just east of the highway. The thunder and lightning was nearly continuous as the storm moved ever closer. It seemed far more intense than it really was.

The storm cell was still highly elevated, it produced some small pea sized hail and heavy rain. There was virtually no wind at the surface. You can see the back side of the storm as it passes, this particular shot was taken looking Southeast.

Here's my position relative to the storm to give you a better idea of what I was seeing.

Fresh towering cumulus going up to my immediate west along a turbulent zone of convergence and mixing aloft near the leading edge of the prior convection.

This was the second storm cell which later spiked on radar. When this photo was taken it was still in its infancy but at this point the surface warm front was getting closer and it was later in the day so boundary layer mixing was increasing. This allowed the storm to mix down further and at least appear to be getting closer to the ground.

A little while later the same storm seen in the previous image is now east of me and beginning to hit 65dbz on the radar. You can see the rain shafts from the storm directly in front of the power lines.

Here's the radar showing how intense the storm actually appeared on radar despite its benign appearance visually.

This is a stylized image of the storm as it continues eastward. I've used a graduated neutral density filter to darken the sky and create this vibrant image. At this point the storm was hitting 68 dBz and producing some small hail. A warning for Durham Region was issued, and this storm eventually made its way out over Lake Ontario. I tried to keep pace with the storm but gave up, it was moving at well over 80 km/h.

The setup for storms was driven by a low scooting just north of Lake Erie and Ontario, the supercells in Southcentral and Southeastern Ontario formed along the warm front where a marine / lake breeze boundary interacted with the surface warm front and trigger storms

A weak elevated supercell in a low energy but moderate shear environment approaches Milton

The storm is now passing through Milton, you can see mid level clouds flowing into the storm from the Southeast (image looking west). It also presents a bit of a vaulted type structure with the usual lateral tilt of the updraft. Slight clearing between the "hail" region of the core and the heavier rain is visible just to the right of center. The biggest problem with this storm if any is the fact that it remained elevated with limited boundary layer interaction and hence produce virtually nothing as far as wind at the surface.

Inflow / outflow and rain as the storm passes overhead and looses some of its structure

Here a screenshot from PYKL3 (Android radar software) showing my location and a weak couplet appearing on the NWS Buffalo Nexrad radar.

Here's the Meso Analysis sounding for a point nearest the storm at the given time. You'll notice the storm is entirely elevated with very little cape and very low topped since the LFC/CCL EL is ~7km. lon=-79.813855 lat=43.555635

The hodograph data shows little in the way of dynamic shear, all the veering in this ground relative hodoraph is below any of the convective instability.

The storm relative hodograph shows a very different story, veering winds with supportive inflow exist well above the ground into the mid levels allowing the storm to still rotate (although very slowly) despite being elevated. This explains why this storm took on a supercellular structure.

Hard to believe that less than a week after the ice storm I was out chasing a large ragged bowing squall line with temperatures around 25 Celsius. April is really a month of extremes!

Storm motion with this bowing segment was 59 degrees (Northeast) at 57 knots (105 km/h) You'll see how the storm progressively bows as it progresses north along the line

Here's a quick screen grab from my tablet showing the radar at the end of my storm chase day. You'll notice the a large bowing segment heading off towards Uxbridge, that there is the storm which bowed out right over my head in Bolton/Caledon.

A smattering of ice pellets cover the roof of a home in Leaside, Toronto as the first wave of precipitation from the impending storm moves in

The low elevation of Leaside in Toronto allowed the snow up north to instead fall as ice pellets down in the city. The expected change over to rain was stunted as more cold air flooded in and mixing began to occur aloft.

Commuters in Brampton near hwy 50 & Queen St get on a Zoom bus as heavy wet snow falls. The snow was not expected, a combination of colder air flooding in and additional mixing aloft meant that the precipitation, which was supposed to remain as ice pellets eventually changing to rain fell almost entirely as snow with the first wave of precipitation.

A "surprise" winter storm blankets Langstaff Rd just west of hwy 27 with a coating of wet snow. This unusual late season storm left many municipalities unprepared to treat the icy road surfaces and commence plowing operations. The snow also created an additional forecast element not forseen, with a fresh blanket on the ground it meant that temperatures were able to remain cooler longer and this would aid in the freezing rain process which would begin with the second wave of precipitation much later in the day towards evening.

Normally at this time of the year the first spring sprouts are shooting out of the ground, but that seems unlikely given the fresh coating of snow.

This was the radar image at the time showing just where the snow, ice pellets, freezing rain and normal rain sat. You can see the blues and purples (snow) effecting the GTA and areas eastward while much of the Hamilton, Halton and western portions of Mississauga were seeing a good mix of ice pellets (orange). Further south, along the QEW on the south shore of Lake Ontario most of the precipitation was falling as rain (green) and to the west a pocket of freezing rain (pink) had developed over Kitchener, Waterloo, Guelph and other surrounding communities due to cold air damming at the surface.

As I started my missing late at nigh to find freezing rain as the second wave of precipitation moved in ice accretion was rapidly building. Here, a road sign stands frozen near Caledon.

The streets of Orangeville required a pair of well sharpened skates.

A driver heads west along an ice covered Broadway in downtown Orangeville

Glazed city streets

Looking at this photo it sure does not look like April 1st, and no this is not an April fool's joke I've concocted, it's a not a joke at all! Mother nature decided that we've not had enough winter this year and it seems even with balmy days between they are simply teasers. (There has been no Photoshop work done to this photo, it was taken purely using a Cokin graduated tobacco coloured filter)

My car (not visible but right of the frame) was actually partially blocking a lane. It was all fine and dandy since there was no traffic and this snow was low drifting stuff. Then just as a few cars came into view the wind started blasting and the drifting snow became a low visible wall of white a few feet tall. It was more than tall enough to shroud my car from any unsuspecting drivers so I made haste and got out of here as quickly as I could!

I'm not sure if the municipalities or province for that matter still has any salt in reserves. Whatever the case, this highway was just glazed over! I almost wiped out just stepping foot outside of my car! April 1st huh? Sure feels like I'm north of the Arctic Circle, not north of Orangeville.

This is the 0 visibility stuff blowing where I was parked. Yeah, not a good idea!

There were tons of little snow devils (vorticity pockets known correctly as eddies) dancing around in the fields. Unfortunately, what looked cool to my eye looked like crap to my camera. But for the record, you can see the winds and squalls made things nasty in these exposed places.

Here are some of the cellular convective snow squalls heading southeast into the Greater Toronto Area (I'm looking southwest). Some of the tops on these squalls must have been pretty high but I did not see any lightning returns on any of my services. (Again no Photoshop, just that Cokin Tobacco filter)

Yeah, the car was clean! I decided after the fact this was a bad idea, seeing as I was actually getting dirty! Note to self, don't unnecessarily go out of the way to drive through snow squalls when the car is clean!

No rainbows here, but the convective lake effect snow bands were so cellular in nature that you could literally be under a clear sky above while all around you snow is pouring down.

Just to illustrate the point.

This was highway 10 just north of Mono, as you can see this looks it typically does in the period between late November and early March. It sure is cruel to have it look like this in April, it's simply not funny!

Ever so slowly

Didn't need a sign to figure that out

Traffic creeps along highway 7 near Martin Grove Rd in Woodbridge

This homeward bound Honda with summer tires was heading nowhere quickly

This Mazada 3 driver attempts to make it home on a residential street

Vehicles struggle to make it up the Woodbridge Ave hill near Kipling.

Two vehicles face the wrong way on highway 401 in Toronto after colliding as part of a larger 5 car collision

My poor electric snow thrower had a hard time cutting through this 30 inch deep snow drift

This was one of hundreds of accidents that occurred along highway 401 in Toronto during the morning rush hour. Heavy snow and poor conditions made this morning a rush-hour from hell

Several hours after the snow stopped falling I began the task of diggin out

Weak towering cumulus clouds congealed to form a weak rain shower. This "storm" never amounted to anything.

New storms formed as a wave of activity pushed into the Windsor area. Storms formed near Oil Springs and expanded northward. This one cell formed ahead of the mess over London and had some brief interesting characteristics. This was taken near Arva looking south.

After the London storm was eaten by the more dominant storms to the west I headed north and watched as a meso-triple point (storm scale feature) came together just west of Ilderton.

An isolated cell formed north of the main body of the storm system just north of Ilderton and popped out a lowering

There was some major convergence & forcing between the two storms, cloud motions intesified and stuff was happening at 10's of meters per second.

This was a huge outflow scud bomb shelf thingy facing towards the inflow from the south

This was all inflow and there was violent mixing above my head with a sharp temperature increase outside of the car as inflow winds overcome any outflow.

What may have been a brief wall cloud or inflow/shelf feature formed and I shot video since photos would not do it justice. After the main action started to press east of my location I snapped this photo of a tail cloud. There was some major inflow action along it.

After the storm(s) lost their structure I punched back through what was a rainy core and emerged on the east side of the complex near St.Mary's

This was a crappy ragged shelf cloud, it looked cool (I guess all clouds look cool to me) but it posed zero threat,

This wide shot gives an idea of perspective with regards to the size and scope of the flooding.

Persistent local rains in excess of 50mm created localized flash flooding. These vehicles in Concord (Vaughan) became flood victims.

Illuminated by the not too distant city lights, a massive shelf cloud comes into view as it bares down on Milton

The shelf/roll cloud slowly getting closer

As the MCS moved towards Milton around 1:50AM a shelf cloud & roll cloud developed

The 8AM surface map paiting the setup for the day. The MCS visible over WI/MI would later be the trigger point for the convection

The meso NAM bufkit data looked alright, there was plenty of energy to be had and while support was no great there was enough instability to kick off some good storms

The real-time MESO analysis RAP soundings around the time storms started to fire up

This was the first storm of the day, it formed in a triple point convergence zone between lake breeze boundaries and an outflow wave from the MCS which was now crossing Georgian Bay

Here's the storm a little later on in life

Just after this photo Mark Robinson and I bailed and left the Innisfil storm to go chase storm which were forming to our immediate west

A shelf cloud on the leading edge of the MCS outflow near Beeton, ON

Here is the shelf cloud approaching

This is pretty self explanatory. It was neat to see dust and other small debris blowing, winds were kicking up into the mid 50's with maybe an isolated gust as high as 60.

Tower going up on the western flank of what remained of the outflow in Vaughan

Mark Robinson and I spent the better part of the afternoon waiting for initiation which never came. We agreed it was a bust and went our ways. Just as I started east along hwy 9 towards the 400 a developing tower to my north with faint echoes on radar caught my attention.

This is how I planned to document what was quickly turning into a bust, beautiful crepuscular rays in Orangeville

Surprised I was! What started as a faint echo over Georgian Bay quickly grew and morphed into a beautiful mothership of a supercell which I intercepted near Baxter, ON.

Words can't describe what was going through my mind! The structure was unreal, and winds were south-easterly veering to southerly before a dry but still warm RFD kicked passed.

The storm did briefly produce a well defined wall cloud, but more impressive was the notched out RFD cut at the back of the storm

Easily the best structure of the year so far in Ontario. I can't believe there was no significant severe weather. It was a great storm!

Here is the 9PM meso-analysis sounding for the nearest airport effected by the supercell, by this time the supercell was passing through Baxter and south of Borden

Here is the 8PM meso-analysis sounding for the nearest airport effected by the supercell

As the day went on the RAP model consistently increased the amount of surface energy present with shear and tornado indices increasing

This was the first RAP model I really dug deep into. Numerous key shear elements were coming together to make the day "interesting"

Here's the core literally falling out of the storm over Milverton looking west from Poole

Near stationary storm near Poole, Ontario