#2789 "July 4th Fireworks"

#2789 "July 4th Fireworks"
14x11 inches oils on canvas

July is typically the month when even pulse-type thunderstorms can rapidly achieve severe proportions and deliver damaging impacts. Intense thunderstorms can burst like popcorn on a hot skillet. The environmental clues to accurately predict which kernel is going to explode next can be a big challenge and quite beyond the capabilities of numerical weather prediction. I employed deformation zones and their intersections at various levels in the atmosphere to try to solve those riddles when I worked the "Severe Desk" and carried that responsibility to provide a service. 

Supercell Thunderstorm Strucutre

What might appear to be chaotic convection is actually well organized. Convection requires heat, and humidity to create instability and a trigger to ignite the fuse. Winds in the atmospheric ocean control how the ensuing convection is organized. The storms can be simple pulse convection that go up and then come down extinguishing the fire. But with more wind shear, the updrafts can evolve into multi-cellular storms. The wind shear patterns required to create super-cellular severe thunderstorms are even more exacting but once formed, supercells can persist along their destructive and dangerous paths for several hours. Supercells can dominate atmospheric wind patterns.  

On Tuesday, July 4th 2023, one pulse thunderstorm along Highway 29 just north of Brockville caused flooding rainfalls and nickel-sized hail before the warning was issued. That cell collapsed soon afterward highlighting that it is essential to understand and anticipate the type of convection that might develop in a given weather situation.

Simultaneously, the multi-cellular thunderstorm I painted was far away to the west of Singleton closer to Belleville along the north shore of Lake Ontario. That convection was in a different atmospheric environment. I was intrigued by the structure of the cumulonimbus complete with mammatus and a short and steep flanking line. Rain shafts could be traced to each cell of the thunderstorm that was more than 100 km to the west. Another thunderstorm cell was even further away to the northwest and waiting in the wings. 

Climate change is contributing significantly to the impacts of severe convection. The atmosphere can hold an additional 7 to 8 percent more moisture with each degree Celsius increase in atmospheric temperature. Both heat and humidity are the essential fuels for convection. The atmospheric winds are also weaker as the temperature gradient decreases between the equator and the rapidly warming poles. The resultant convection is more likely to track along boundaries in the lower atmosphere with each cell dropping its ever-increasing precipitation load along the paths taken by the preceding cells. 

The effects of lake and land breezes for locating these convective tracks cannot be underestimated. The shape of the shorelines also plays a crucial role as well. There is much more to explain but be assured that flash flooding from such convection will become increasingly important in the climate future probably in regions that have never experienced it before. 

Water Vapour was my Go-To Data source to decipher the areas of convective threat...
From there I would drill down to locate the precise triggers and thus the Concern of the Day.

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Warmest regards and keep your paddle in the water,

Phil Chadwick