#2907 "November Sunset Edge of Snowsqualls"

#2907  "November Sunset Edge of Snowsqualls"
11 X 14 (inches). Started 9:00 am Saturday, November 30th, 2024 based
on the previous afternoon at 4:30 pm. I was beside the red Muskoka chairs
overlooking the lake to our west from N44.522754 W76.105050.
The clouds were really talking.

We were enjoying a spectacular Singleton sunset. The typical Great Lakes snowsqualls were raging in the onshore flows. But not at Singleton, for some very good meteorological reasons. Weather and geography are just some of the reasons why the Singleton Sanctuary is so special. 

The low-level winds had a northerly component being drawn into the westerly snowsquall setting up on the Tug Hills of northern New York State. About five feet of fresh snow would accumulate on the Tug Hills and the adjacent Interstate 81 over the course of the next five days. Highways all around the Great Lakes would be treacherous and many would get closed at least temporarily. 

The cirrus was part of the circulation around the upper low which was driving the northwesterly flow of cold Arctic air. The weather pattern was stagnant with the dominant low stalled over western Quebec and northeastern Ontario. Fresh Arctic air was being pumped over the unusually warm Great Lakes. The lake temperatures were well above normal values. 

The meteorology of snowsqualls is actually fairly simple. Cold air is delivered by moderate winds over warm water. The Arctic winds need to be well aligned over a deep layer in the lower atmosphere. Snowsqualls require at least 13 Celsius degrees of difference between the lake and the atmospheric temperature around 5000 feet above the lake (850 mb). The intensity of the snowsquall convection increases with this temperature difference. Thunderstorms are likely if the temperature difference exceeds 20 degrees. 

The Singleton Sanctuary is located at the yellow star
on the map in the upper right of the above graphic. 

Snowsqualls are essentially a form of severe convection. They only lack the towering heights of summer supercells. The snowsqualls are also more intense with winds that are really well aligned. The impact of snowsqualls can far exceed those of a dramatic summer thunderstorm. 

Snowfall accumulations can reach extreme limits with the duration of these events and the time the winds point at particular onshore locations. The geography of the Great Lakes favours some onshore locations more than others but we will leave that meteorology for another day. 

I love snow but towering snow banks can make everyday life come to a halt. Singleton only gets really significant snow accumulations from slow-moving winter storms or the rare 230-degree snow squalls off Lake Ontario. 

For this and much more art, click on Pixels or go straight to the Collections. Here is the new Wet Paint 2024 Collection. 

Warmest regards and keep your paddle in the water,

Phil Chadwick