Best time to observe in Melbourne

[MattT]

Hi Melbournites,
Is there a best time for clear skies in Melbourne??? I work lots of evenings and find it hard to get up before sunrise but the few times I have, have noticed that the sky is clear when it was cloudy around midnight.
Is this common?
:question: Matt

[Sarge]

The one thing about clouds in Melb, is they are always common.:lol::lol:
Check out these sites for cloud forecasts.

http://www.skippysky.com.au/Australia/

http://www.7timer.com/index.php?lang=en

Clear skies

Rod
:D:D

[pgc hunter]

Best time to observe in Melbourne?!

Summer. We actually see sunshine and clear skies, and better seeing than in winter. April thru to Sept is essentially permanently overcast and ice cold wintry hell with an endless precession of cold fronts. You may get the odd clear night here and there, usually seperated by weeks and often falling on a full moon plagued by crap seeing. Transparency however tends to be best during the cold half of the year. Those occasional cold clear nights in winter without the moon are tops for galaxy and nebula observation.

Skippy sky is good with cloud forecasts, but do yourself a favour and ignore their seeing predictions. Skippy sky's seeing predictions is based on the presence of the jetstream, and doesn't take into account any lower level atmospheric activity.

[HCR32]

Too many factors have to come together for the best seeing which doesn't happen often. Your best bet is to get out there more often take note of the stars twinkles and become your own judge. I did get out one day in late spring with high winds and found that to have been to date the best seeing. Sometimes I think mother nature throws in one element that would usually put you off setting up just so that you miss that perfect night.

One thing to keep in mind is day and night temp differences the closer they are to each other the better. I'm guess that's why I've also heard that summer it the best time of the year too in general.

[Moon]

Sometimes is does clear up in the morning. More often I notice it clears up just after sunset. This happened to me recently - it was raining and cloudy all day then cleared at sunset and was clear all night. Video (http://youtu.be/-8NcX03HZ8w)
Keep an eye on the forcast and look out the window a lot. If you have an all sky camera, you can also get some software to wake you up when it's clear.
This site is also worth keeping an eye on:
http://www.yr.no/place/Australia/Victoria/Melbourne/hour_by_hour_detailed.html

James

[andyc]

A common weather pattern in Melbourne is one that plays out over a week to 10 days, with the passage of the high/low pressure systems. A front will arrive with rain/grimness/storms, and turn the winds to the south/southwest. That usually means anything from cloudy to quite unpleasant across Vic. The front(s) will clear, but leave us in a spell of southwesterly winds, with a high pressure system based somewhere near the Great Australian Bight. This often lasts about 3-6 days or so, with onshore breezes and clouds that are initially quite thick, thickest towards the coast, perhaps with showers, gradually reducing as pressure builds (the high system sliding eastwards and getting closer to Melbourne). If we're lucky, the high will pass over Melbourne, giving sunnier days for a day or two, before the winds shift into the north/northwest after the high. That time is our best chance for clear skies, with the winds coming off the continent, but it only lasts until the arrival of the next set of fronts, starting the pattern over again.

In summer, there's quite a lot of chance of sun, as the lows are usually further out to sea, and the sun is stronger so it can 'burn off' stratiform cloud that comes in from the coast on the southwesterly/southerly winds. That means northern Vic has bettern chances of clear skies, but Melbourne can do OK in summer. In winter, the sun isn't so effective at doing this, and the lows pass a bit closer, all adding up to much longer spells of cloudiness. You wait patiently (!) for the wind to turn into the north after a high pressure arrives/passes by, then that only lasts for a day or so ahead of the next rain band. Sod's Law of course will put that window of opportunity at Full Moon as pgc hunter says (or in the case of this week, with a big fat evening gibbous Moon), but when spring returns and a stronger Sun, and the lows not passing so close, we should have more chances of clearer skies.

I'm not so sure about evening versus morning patterns, but you have more chance of good evening conditions at least in part because the air temperature will be further from the dew point at dusk relative to later in the night (which means risk of dew as well as mist and poor transparency if relative humidity gets too high near the surface).

I'm reckoning on about one or two clear nights per New Moon period at the moment, but in spring/summer/autumn it was more like five or six at least. Of course I'll end up having social plans made for those nights well in advance...

For good satellite images, I've been using:
http://realtime2.bsch.au.com/vis_sat.html
You get much better satellite images than on the BoM and can zoom in on Vic. On the visible satellite images, you can get a nice 'feel' for whether coulds are melting back to the coast or not, and other changes of weather by setting up animations of the hourly images. You can use IR images for overnight, but beware that low (warm) clouds often do not show up well on night-time IR imagery.

[David Niven]

How I wished on a Night,
When the Moon has gone to bed,
And the angels whispered to silent the wind,
And put the clouds away, in the closet,
A Night when the breeze is still and diamonds sparkle above in a pitch black canvas.
If you hold your breath, my friend,and listen quietly,you may hear the Universe sing!
Those were the Nights, to remember, to treasure and to long forever more......

[andrew_d_cool]

G'Day,

"Skippy sky's seeing predictions is based on the presence of the jetstream, and doesn't take into account any lower level atmospheric activity."

Sorry mate, but that's just cr*p.

Skippysky does, and always has, taken into account winds at the standard ground level of 10metres. Just like it says in the online Help file,
and just like it does in the code.

In fact the last adjustment to the algorithm applied more weight to the 10m winds, based on a paper describing the greater influence of boundary layer winds on Seeing.

Now if people actually paid for the product, and thus enabled a whopping great download quota and mega fast connection, then data for every layer in the GFS model could be downloaded, and the Seeing forecast could be expected to improve. As it stands, for free you get the two most important of the 26 available layers in the model.

But I guess it's just easier to whinge at a freebie than do something about it that involves reaching into your hip pocket? Or, Heaven Forbid, read the Help file.

Kind Regards,

Andrew Cool
Author, SkippySky

[Varangian]

Talk about selling your product:question:
You might have been a bit more diplomatic in your response. :thumbsup:

[pgc hunter]

The things people get offended by these days. Jesus christ. :screwy::rolleyes:

Firstly, I use Skippysky all the time when planning an obs session, as its cloud predictions are very good in my opinion. I mentioned this in my post to which you took offence :rolleyes:

Secondly, I never took a swipe at skippysky for its seeing predictions, all I said was that it uses the jetstream to predict seeing, and I've found its seeing predictions to be not very accurate, for my area at least. This is not the fault of skippysky and never said it was. Its just my findings based on many nights. It's hard to predict seeing as there are many local and atmospheric variables at play. And for this reason, pretty much any model that predicts seeing (e.g. Clearsky clock, 7timer) is rarely going to be accurate. So no, it's not an attack at your product. it's fact.

I don't see how any of this is "whinging", but whatever, everyone is free to believe what they want. :rolleyes:

[rustigsmed]

It seems that whenever I check the forecast all i ever see is 'Melbourne; windspeed 25-35km/h', cloudy. in addition, i think i almost became claustrophobic from the cloud cover oct/nov last year. fair dinks, the wind never seems to ease.

I always thought mid to late autumn was a winner, calmest conditions by far.

[andrew_d_cool]

NO, this is what you said :-

"Skippy sky's seeing predictions is based on the presence of the jetstream, and doesn't take into account any lower level atmospheric activity."

Note the " doesn't take into account any lower level atmospheric activity"

That's the erroneous statement. It is simply not true, and needs correction.

As for the including the jetstream, I know top notch planetary imagers
who hang off every movement in the jetstream. In fact, some prefer a little jetstream activity to none at all!!

So there's good reason for incorporating the jetstream into the Seeing algorithm.

Now whether you find the predictions accurate or not, is indeed a matter
a matter for individual observation.

Believe me when I say I personally wish it was more accurate.

And I'll happily accept a more accurate algorithm that anyone can cite
in the literature, that can be implemented using GFS data.

Andrew Cool
www.skippysky.com.au