Hi Folks,
I run the SkippySky site.
It's clear that a few folks haven't taken the time to read the online Help
file, or for that matter to click on the "contact SkippySky" link that appears above every map.
So here's a brief rundown. The colour scheme uses ten colours to cover
the predicted range of cloud cover from 0% to 100%. It follows then that the dark blue covers from 0%..9.9%, the next lighter blue from 10%..19.9% and so on.
That darker blue ***does not*** necessarily mean NO cloud cover!
It means somewhere between buggar all cloud and ~10% coverage.
Now I don't fiddle with or massage the predictions as churned out by
the American GFS weather model, beyond the fact that the contouring
will smooth out the coarse 0.5 degree resolution data a little.
While we're on it, take note of that data resolution of 0.5 degrees. That's about 1 data point per 40km. The Yanks call it "high resolution", but no one should expect to get a deadly accurate forecast for the cloud cover over the Hills hoist in their backyard.
My constant plea is for people to think in terms of trends in the data, rather than to seek out elusive pinpoint accuracy.
And yes, 7Timer, Unisys, Meteoblue, astroforecast.org and others all use the same source GFS data. I started SkippySky because I really don't like the format of 7Timer and the original CSC (which of course uses different Canadian source data and doesn't cover outside CONUSA)
Remember that when you provide your lat/lon to these other sites, they
are converting that back into a grid of data where each data point covers about 40kmx40km. At least a weather map style presentation provides a feel for what's coming your way.
The Seeing field is the only parameter that is manufactured locally in SkippySky. We use the GFS windspeed vectors at ground level and up at the Tropopause to derive a weighted index for Seeing, which is NOT related to any scale of arc resolution, certainly not the Bortle scale as I've seen on one website commenting on SkippySky.
Again, I urge you to think of trends in the data. The darker the blue
on the Seeing maps, the more likely you are to have better seeing.
I can't put my hand on my heart and promise 2 arcsec seeing if the Seeing is rated as a 10. But it might just be worth your time to drag the scope out.
I can't speak for what the other guys do with the GFS data that they download and present on the net. I don't have their source code...
If all is running well with the servers locally, and with the GFS servers in the USA, then SkippySky is updated every 6 hours. Every map has the datestamp and timestamp of the GFS data at the top left hand corner of the map.
Which reminds me, I'll have to alter daylight saving time...
As for the accuracy of the GFS data? The NOAA/NCEP/GFS is the world's leading Numerical Weather Prediction model. No matter what you think of any inaccuracies, you won't get better forecast data.
If you have queries, please PM me at
contact@skippysky.com.au
Cheers,
Andrew Cool
Adelaide