Weather forecasts question - how significant is "high cloud"?

[Zermelo]

I had a finely balanced decision to make yesterday about whether to stay up and attempt a post-midnight astro dark session, factors including:

- BBC/Met Office forecast was "clear all night"
- BBC/Met Office forecasts have been woefully innaccurate, both day and night
- Clearoutside was forecasting clear early evening, but later on it had "0% low cloud" and "75% high cloud" cover
- Lack of moon
- My other half is somewhat keen, but I didn't want to keep her up that long for a potential damp squib
- It's very late, and not dark for that long
- There look to be one, perhaps two more clear nights forecast in the coming week
- I have a new eyepiece and filter arriving soon 😀

I decided not to wait up, and instead charged my batteries for a possible session this coming week. I see in the observing reports this morning that at least some UK people did have clear skies, so I am a bit regretful. I've only started observing in the last couple of months, so I may have been spoiled by the number of good evenings we have been having? Looking back at some of the older comments, I see people wishing they'd never bought their scopes, after fifty or sixty days without sight of a star!

Anyway, to my question. Was I unwise to be put off by the Clearoutside prediction of "75% high cloud"? I mean, leaving aside the obvious possibility that they might be wrong anyway, Is there any difference in the effect on observation between low, medium and high cloud? Would you take one more seriously than another? I noticed that the "visibility" line was still saying 10 miles (the highest it ever seems to say) even when cloud cover was 75%. Is that significant?

Tonight is looking very similar!

[Neil H]

Hi mate we had a lovely clear night here in Luton started with clouds but I work on if I can get a 3 star alignment between clouds  I stay out , I even got the planets this morning , the mount is still out now ready for tonight 

[Waddensky]

High clouds are mostly cirrus, if the layer isn't too thick it's possible to look through them to observe brighter objects, like planets and open clusters (and they cause wonderful halos around the Moon).

Low clouds, like stratus, most likely hinders observing more. Cumulus interference depends on the amount of cloud cover, the sky between the individual cumulus clouds is often remarkably clear so I'm not bothered most of the time when there are a few clouds drifting by while observing.

[Zermelo]

1 hour ago, Waddensky said:

High clouds are mostly cirrus, if the layer isn't too thick it's possible to look through them to observe brighter objects, like planets and open clusters (and they cause wonderful halos around the Moon).

Low clouds, like stratus, most likely hinders observing more. Cumulus interference depends on the amount of cloud cover, the sky between the individual cumulus clouds is often remarkably clear so I'm not bothered most of the time when there are a few clouds drifting by while observing.

Yes, that's a fair point - it could be 75% cloud but thin stuff, and my kit isn't going to see many DSOs in the first place so I'm mainly looking for doubles and clusters.

[Zermelo]

2 hours ago, Neil H said:

Hi mate we had a lovely clear night here in Luton started with clouds but I work on if I can get a 3 star alignment between clouds  I stay out , I even got the planets this morning , the mount is still out now ready for tonight 

Glad you saw some stuff Neil, I'm obviously not hard core!   I think if the forecast stays the same tonght I'll stay up.

[Neil H]

All you can do i set up and try . I dont mind setting up just for an hour . Getting up a 3 for the planets is easy i get up that time if i going fishing the wife come up the lake about 10 am when everything is set up lol 

[Zermelo]

Well, the conclusion was that last night (25th) was showing a similar forecast (high cloud only, starting from about 23.00) but I went out anyway and didn't see a trace of cloud until I finished at a quarter to 2! Brilliant night.

[banjaxed]

Reminds me of a friend from years ago who told me ‘the only certain way to tell what the weather is like is look out of the window’ 😀