saw a clear western sky

The local Clear Sky Charts were looking good. The Newmarket one showed the skies clearing in the afternoon and remaining that way, mostly, until after midnight.

And when Peter called a GO for the local RASC observing session, I reconsidered observing in the evening. Seize the opportunity. The Clear Outside prediction looked pretty good. The Weather Underground 10-day graph showed the cloud cover dipping to 6% at 9 PM.

I checked the Environment Canada data.

Observed at: Toronto Buttonville Municipal Airport
Date: 5:00 PM EST Thursday 22 February 2018
Condition: Partly Cloudy
Pressure: 103.9 kPa
Temperature: 0.8°C
Dew point: -8.2°C
Humidity: 51%
Wind: E 12 km/h

Detailed Forecast
Issued: 3:30 PM EST Thursday 22 February 2018
Tonight Partly cloudy. Becoming cloudy before morning. Risk of freezing drizzle before morning. Wind northeast 20 km/h becoming light early this evening. Low minus 6.

But some of the other local tools were not so optimistic. Good To Stargaze showed at least 30% cloud cover and building through the evening. And the satellite imagery from AWC showed streamers flying north-north-east over Lake Ontario and skirting Lake Simcoe. Toronto looked OK but York-Simcoe not so much.

So I hoofed it upstairs and looked outside. Clear! Sunset was in full display with distant clouds to the north-west. South? Looked good.

So I began the backyard setup. Took the Meade ETX 90 RA outside (without its base). Installed it on the large Mamiya tripod. Essentially, an alt-az setup.

Prepared an observing list in SkyTools. Mostly doubles. Some Messiers to revisit. Over 90 entries.

Reviewed my session pre-flight check lists...