Will skies be clear over southern Ontario Tuesday night?

Clear skies are expected.

Some high cloudiness is likely to move over southern Ontario after midnight and before dawn (illustrated below).

Will skies be clear over southern Ontario Monday night

Clear skies are expected, with a strong high pressure ridge moving over southern Ontario (illustrated below) providing a cold and dry airmass with strong subsidence that is likely to suppress any low-level lake-effect clouds during the early evening near the Great Lakes. By Tuesday morning, high-level moisture is forecast to move eastward over the Great Lakes region and may cause some high clouds to appear.

Will skies be clear over southern Ontario Sunday night?
Partly clear skies seem likely, except for more cloudiness southeast of Lake Huron and Georgian Bay due to lake-effect cloudiness flowing downwind from the warm waters (illustrated below for low-level moisture at the 850 hPa level). Elsewhere, skies are likely to become partly clear due to diminishing mid-level moisture during the early evening (illustrated below for the 700 hPa level) although another region of mid-level moisture is forecast to move southeastward across southern Ontario after midnight and could cause increasing mid-level cloudiness (over regions that are not under low-level lake-effect cloudiness).

Will skies be clear over southern Ontario Friday night?

Skies may become partly clear by mid-to-late evening over regions near Toronto and GHTA as moisture at low and mid-levels decreases during the evening for several hours, until moisture and cloudiness increases again. The charts below show the diminishing moisture at low and mid levels during the evening. Other factors contributing to partly clearing skies include subsiding motion (contributing to sink and dry the clouds), lack of a jetstream overhead, and moderate winds (preventing fog formation overnight). Skies could remain cloudy due to low-level cloud below a thermal inversion (near the 850 hPa level) which might prevent vertical mixing that would allow the low cloud to dissipate.

Will skies be clear over southern Ontario Sunday evening?

Partly clear skies after sunset will most likely allow starlight to be visible, but lots of high cloudiness will most likely be visible overnight as a result of jetstream-level moisture (illustrated below) along the jetstream over southern Ontario (illustrated below). Some breaks in the high cloud might occasionally cause skies to appear mostly clear before moonrise, but the high cloud will probably be easily visible under the bright moonlight.

 

 

Will skies be clear Friday night over southern Ontario?

Skies are likely to become clear before sunset except for high cloud that may or may not be thick enough to appear as thin cloud. The persistent high cloudiness is flowing northeastward across southern Ontario with a strong Jetstream (illustrated below). Moisture at jetstream level might become thin over some regions (illustrated below for mid-evening) to allow the sky to be mainly clear, while at other times the high cloud may be more distinctly visible (particularly under the nearly full moon).

Will skies be clear over southern Ontario Thursday night?

Cloudy skies are expected, caused by moisture moving eastward across southern Ontario (illustrated below for mid to high-level moisture) beginning later Thursday afternoon, associated with an upper level weather disturbance. Cloud may be thin enough for the full moon to be easily visible early in the evening in some regions, especially in urban areas where the full extent of widespread high cloud may not be obvious, and give the impression of a partly clear sky.