Will skies be clear over southern Ontario Wednesday night?

Clear skies are expected under a strong high pressure ridge, except for some high-level moisture that is forecast to gradually spread eastward over southwestern Ontario overnight ahead of a warm front. The jetstream-level moisture may appear as cirrus cloudiness by morning over some regions. Below, a chart shows the location of the high pressure ridge axis west of southern Ontario (chart from weather.rap.ucar.edu). Northwesterly winds, dry air and subsidence east of the ridge will be contributing to clear skies. The chart of 250 hPa-level moisture shows increasing potential for thin cirrus cloudiness to appear over southwestern regions.