#2428 "June Evening Convection"

I remembered this evening of convection from early June. Summer convection typically rides the eastward extension of the Lake Ontario lake breeze and passes just north of Singleton Lake. We get treated to a beautiful sunset display of backlit clouds but it seldom rains on our parade. The rain water is always appreciated but this liquid will still fall into the greater basin of the lake system. It takes about six days for the water to crest at Singleton after a heavy rain event. 

The lake breeze convergence lines pictured result from one in which the average winds are almost calm over the Great Lakes. The onshore lake breezes described in the graphics dominate the pattern and the "shadow of the cool waters of the lake" are almost equidistant inland. Typically the general flow pattern with a strong convective outbreak is associated with southerly or southwesterly winds that deliver the added heat and moisture energy into the convective equation. These average winds add vectorially to the lake breeze dominated cloud patterns. The net result for Singleton is that the Lake Ontario lake breeze generally lies just to the north pointing through Delta. 

The shape of the shoreline also dramatically influences the pattern of convection. Large bays on the lake produce divergent onshore lake breezes. Points or peninsulas create very focussed, convergent lines of convection. Prince Edward County and the Niagara Peninsula are good examples of convergent lake breezes. I made my operational career out of forecasting lake and land breezes. The forecast was almost as simple as vector addition to discover the convergent and divergent lines in the atmospheric boundary layer. It made the science not only fun but productive for not just summer but also winter severe convection. 

Long before the creation of Canada in 1867 and the "Atmospheric Environment Service", the lake breezes were important to the weather. It was in May 1871 that the new Canadian Parliament provided $5,000 to launch the federal weather service. They would employ me a bit more than a century later. May is the prime time for Ontario supercells and that may not be just a coincidence. The publication of historical climatological data in Canada also started in 1871. A century earlier a tornado surfing the Niagara Peninsula convergence line between lakes Erie and Ontario made the news. 

"The year 1792 was marked by another calamity, which, however, proved to be a blessing in the end. A violent hurricane passed over the southwestern portion of the township, levelling all the houses in its path, but at the same time uprooting the trees, thus effectually clearing the woods. A road was afterwards built through this storm-swept region from Fonthill to Port Robinson, and was appropriately named 'Hurricane Road.' " The pioneers did not differentiate between tropical cyclones and supercellular thunderstorms and that is perfectly okay. You have to respect the resilience of our pioneers. They knew that the weather and the environment were important. 

For this and much more art, click on Pixels. Thank you.