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It's the astronomer's forecast. At a glance, it shows when it will be cloudy or clear for the next few days. It's a prediction of when Clyde River, NU, will have good weather for astronomical observing.
The data comes from a forecast model developed by Allan Rahill of the Canadian Meteorological Centre. CMC's numerical weather forecasts are unique because they are specifically designed for astronomers. But they have 984 forecast maps. It can be a chore to find the one you want.
So, I (Attilla Danko) wrote a script to generate the images like the one above which summarizes CMC's forecast images just for Clyde River and the surroundings out to about 15 Kms.
There are charts for 6440 locations.
Details: Read the image from left to right. Each column represents a different hour. The colors of the blocks are the colors from CMC's forecast maps for that hour. The two numbers at the top of a column is the time. A digit 1 on top of a 3 means 13:00 or 1pm. It's local time, in 24hr format. (Local time for Clyde River is -4.0 hours from GMT.)
It is based on Ben Sugerman's Limiting Magnitude calculations page. It takes into account the sun's and moon's position, moon phase, solar cycle and contains a scattering model of the atmosphere. It doesn't consider light pollution, dust, clouds, snow cover or the observer's visual acuity. So your actual limiting magnitude will often be different.
A note about CMC's smoke forecast colors: The chart shows different colors than the corresponding maps because the maps use white to mean "no smoke" but the cloud and transparency forecasts use white to mean "opaque sky". I've chosen colors for the smoke line on the chart that might better represent the color of a smokey sky -- except for the highest levels which, when forecast, means people should stay indoors.
The data comes from Environment Canada's Canada's Wildfire Smoke Prediction System.
To see CMC's full map for a particular hour, click on a colored block. The CMC map your browser will load will be the map closest to the hour you picked. The time on the CMC map might look odd because it's in GMT, while the blocks on the chart are in local time.
It's worth checking a few of the full maps before committing to a long drive out to an observing site.
Or, if you would prefer a simplified thumbnail:
But please don't copy other html or text from this page.
Just keep using it. I intend to keep updating this image for as long as CMC is willing to generate the underlying maps. But there are ways that you can help:
If you find this clear sky chart, or CMC maps linked by the colored blocks, useful please send Allan Rahill of the CMC an email (and feel free to copy me). Allan needs to show his boss that his astronomy forecasts are actually being used.
You can also help keep clear sky charts free for everyone by being a sponsor. Please feel free to tell sponsors that they're cool.
Page updated by d800 at 2020-09-30 03:18:30 which is -4.0 hours from UTC.
Update rank: 6301. Thanks to anyone thinking of sponsoring this page.
Copyright 2020 A. Danko. Page updated 2020-09-30 07:18:30UT on server2.