NWS Digital Forecast Cloud Cover Plot

Amateur astronomers pay attention to the sky and how clear it is. Years ago, we all waited until the evening news to look at the 15 second glance at the satellite image to decide if we should drive out to dark skies to view the stars or not. Today, not only can you get satellite images online in 80 zillion different ways, but you can now also get forecasts for sky cover.

This uses Experimental NWS digital forecast data for sky cover for a 5x5km "grid" of space. Use at your own risk (or fun). Subject to change at any time. Generally, NWS updates the data every hour, but different forecast offices around the county update as often as every three hours or as little as twice a day.

Click on the link above each plot to see these data plotted in a different way. These data are updated 35 minutes past the hour. These CSC like displays are made with apologies to Clear Sky Clock creator Attilla Danko! You are welcome to make comments to bbunge@ladyandtramp.com.

Create a custom plot (enter degrees): Lat:Long:

Laurel Highland Star Cruise
Cloud Cover 
Hour (Eastern) 
Day 
Tuckahoe State Park (MD)
Cloud Cover 
Hour (Eastern) 
Day 
Bowie, MD
Cloud Cover 
Hour (Eastern) 
Day 
CM Crockett Park, VA
Cloud Cover 
Hour (Eastern) 
Day 
Spruce Knob (TMI)
Cloud Cover 
Hour (Eastern) 
Day 
Cherry Springs State Park (PA)
Cloud Cover 
Hour (Eastern) 
Day 
Sky Meadows State Park (VA)
Cloud Cover 
Hour (Eastern) 
Day 
Southern Park (MD)
Cloud Cover 
Hour (Eastern) 
Day 
Oregon Star Party
Cloud Cover 
Hour (Eastern) 
Day 
Pasco, WA
Cloud Cover 
Hour (Eastern) 
Day 
Greenbank Radio Observatory (WV)
Cloud Cover 
Hour (Eastern) 
Day 
Coinjock, NC
Cloud Cover 
Hour (Eastern) 
Day 
Clear                                         Overcast


This data is retrieved from NWS using their National Digital Forecast Database via a XML web service

There are differences between this data and the Clear Sky Clock (CSC). Where CSC goes out about 48 hours, this forecasts out seven days, keeping in mind that forecasts are less accurate the farther out they are. The CSC data is specifically designed for astronomical purposes, the NWS data isn't. The CSC data is a computer model. These are forecasts generated by a human who might be using model, other data and experience as input. NWS forecasters are forecasting percentage of cloud cover. Thin clouds or haze can quickly add up and as a result, it's rare to see percentages less then 15. My personally experience is percentages less then 30 percent are usually good enough for most casual astronomical observing.

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bbunge@ladyandtramp.com

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