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Astrospheric is weather forecasting for astronomers, astrophotographers, and most of all explorers.

Astrospheric was born out of a need to find great locations and to build accurate forecasts for those who like to explore. Combining the amazing astronomy data produced by Allen Rahill at the Canadian Meteorological Center, as well as cloud and ground data, Astrospheric can produce a highly accurate 48 hour forecast for nearly any location in the United States or Canada. Overlaying cloud and light pollution data (courtesy of David Lorenz, University of Wisconsin) onto a map makes it simple to scrub through the next two days looking for the nearest break in the weather.

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Use the map to change your forecast position and see cloud cover across the US and Canada. Tapping on individual hours within the forecast will show details and more forecast information.
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Forecast data provided by the Canadian Meteorological Centre
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Presentation, code, and assets including map overlay tiles © Daniel Fiordalis. All rights reserved.

Light pollution overlay tiles provided by David Lorenz

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The top three rows in the forecast show the hourly sky details. The darker the blue, the better the conditions!
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The sun and moon lines show rise and set times. Dark blue represents the darkest time of night.
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The lower three rows show the ground forecast. Tap on any hour to learn more.
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Cloud Cover

The cloud cover forecast shows how obsured the sky will be be at a given hour by clouds. Darker blue indicates clearer skies, and light blues to white indicate increased total cloud cover.

0% (clear skies) 50% 100%

A note of caution from the Canadian Meteorological Centre on forecasting cloud cover

Cirrus (thin cloud in high altitude)

Numerical models are very good at forecasting the cirrus preceding a weather system. However, you might get the impression that the cirrus is over-forecast . There is a distinction between the opacity and the extent of the clouds. The model could produce an area of 9/10 of cirrus cover which has an opacity of 3/10. In other words, the sky can be covered with a layer of cirrus thin enough to permit visibility of the sky or the stars through it. Thus, under certain conditions, you will have the impression that forecasts predict too many clouds whereas only a thin veil of cirrus blocks the sky. On the other hand, these conditions will not be favourable for astronomical observation, except for planetary observation.

Thunderstorms

Thunderstorms are a small scale weather phenomenon below the resolution of numerical weather prediction models. During the warm season, thunderstorms are a source of difficulty for the weather models. They sometimes tend to be over or under forecast depending on the weather conditions. Thunderstorms can have great vertical extension, the cloud tops often reaching the jet stream level (strong winds), so the clouds are spread large distances downstream. Given the temporal and spatial uncertainty in predicting thunderstorms, the associated cloud deck could be forecast in a corridor further north or south than it should be. During heat waves, please be advised that the forecasts of clouds may not be at their best.

Further information on Cloud Cover can be found on the web here.

Forecast data provided by the Canadian Meteorological Centre

Transparency

Sky transparency uses darker blues to indicate excellent transparency and lighter blues and whites to indicate poor transparency.

Cloudy Poor < Average Average > Average Excellent

Observing deep sky objects such as faint galaxies and nebulae requires excellent sky transparency. Astronomers evaluate sky transparency with the faintest star visible to the unaided eye. In semi-desertic regions such as Arizona, one can see stars as faint as faint as 6.5-7.2 magnitude. At mid-latitudes and in the more humid eastern regions. most of the time sky transparency is limited to the 5.5-6.5 range in the countryside. Sky transparency also varies with airmass type. With a humid airmass the transparency is reduced significantly. With a continental airmass from the arctic, relatively cold and dry conditions prevail, allowing the sky transparency to be at times be as good as in the semi-desertic regions. Good forecasts of such rare starry evenings will clearly be useful to the amateur astronomer.

Further information on Transparency can be found on the web here.

Forecast data provided by the Canadian Meteorological Centre

Seeing

The seeing forecast indicates the level of atmospheric turbulence. Similar to cloud and transparency, the darker the blue, the better the conditions.

Cloudy Poor < Average Average > Average Excellent

Observing planets, planetary nebulae or any celestial object with details at high power requires excellent seeing conditions. When we look at planets, we need high power to see all the fine details but most of the time we are limited by turbulence occurring in the telescope (local seeing) and/or in the atmosphere. During a night of bad seeing we are usually limited to see only two bands on the Jupiter disc and we can hardly use power over 100-150x. On excellent seeing conditions we can use high power and see many bands, white spots, festoons and details in the great red spot.

Further information on Seeing can be found on the web here.

Forecast data provided by the Canadian Meteorological Centre

Wind

The wind forecast (along with temperature) can help in deciding what to wear to stay warm or cool. However, higher winds can make observing or astrophotography difficult, especially with larger telescopes.

Very
Windy
Strong Moderate Light to
Moderate
Light Calm to
none

Note that the actual 10km resolution model used to produce these forecasts has cold bias and weak wind bias on top of mountains.

Further information for Wind can be found on the web here.

Forecast data provided by the Canadian Meteorological Centre

Temperature

The temperature forecast (along with wind) can help in deciding what to wear to stay warm or cool. Large temperature changes may cause tube currents in some scopes as the internal conditions cool (or warm) to match ambient temps. Also, temperature decreases during high humidity can lead to dew.

< -40C 50C

Note that the actual 10km resolution model used to produce these forecasts has cold bias and weak wind bias on top of mountains.

Further information for Temperature can be found on the web here.

Forecast data provided by the Canadian Meteorological Centre

Humidity

Relative humidity (along with temperature and wind) can help determine the strength of dew protection you may need in the field. Cool nights with high humidity and low winds can mean dewing on primary lenses or mirrors.

< 25% 100%

Further information for Humidity can be found on the web here.

Forecast data provided by the Canadian Meteorological Centre