[Wavytone]

What I do...

1. Learn to read the BOM synoptic map and especially the animated time sequences, with respect to understanding:
- the prevailing wind patten over Australia blows from west to east; hence clouds will move that way;
- the wind circulation around a high (anticlockwise) or low (clockwise), and what that means for clouds;
- how the wind strength varies according to the spacing of the isobars (bunched together = very windy, far apart = light winds, the centre of a high = calm)
- what a front means, in terms of wind and cloud.

2. Watch the satellite photos on the BOM site to identify the clear sky vs clouds, bright white = higher clouds, the darker grey fuzz (often hard to spot) = low-level stuff, and the cloud that marks a front.
Use the animated photo sequences to figure which direction and how fast they're moving, so you can have some idea whether there will be a cloud or clearing over you when you want to observe.

Doing the above will enable you to figure whether or not there is a reasonable chance 1-3 days before observing night.

3. Find an online webcam that shows the daytime sky at a location either near, or west of your site. Use this to check if the sky looks clear before you set out. This alone will eliminate many wasted trips.

Failing this, find a vantage point that gives you a view of the sky over the observing site. In my case, i live in Sydney and my observing site is a 2 hour drive west, in the blue mountains. A short walk up the road before sunset gives a distant view of the mountains on the horizon, and I can easily see if it's worth going, or not.

4. Watch and learn the local terrain effects associated with common weather patterns. For example, for Sydney:
- a low off the coast will direct a southerly onto the coast, extending inland, and a southerly off the sea carries moisture = solid low-level cloud which will extend inland 100-200km. However if really desperate, driving inland far enough will eventually find holes in the cloud;
- warm sunny day with a NE sea-breeze on the coast in spring = coastal cumulus clouds or thunderstorms in the afternoon, but clear west of the mountains;
- while on the surface you may have a NE sea-breeze, 300 metres higher up the wind is a westerly (!)

5. If you are under a solid cloud deck in late afternoon, watch out for a deep red sunset. I then check the synoptic map - if the cloud is associated with a cold front, the deep red sunset = clear sky behind the front. So hop in the car and go.

6. Fronts and thunderstorms = clouded out, but if the satellite photo shows there is clear air behind them this will often be exceptionally transparent and can provide good seeing.

7. The microclimate around a particular site:
- black rich soil typical of farms or urban areas - especially ovals and parks = heavy dew, problems with poor seeing due to thermals from the ground as the soil cools, locally cold at night and possibly frost in winter.
- pale sandy soil or sandstone (best) = minimal dew and not so cold
- on a wide open plain, in a depression or valley = fog is likely on a calm winter night, or in summer poor seeing due to thermals from the land.
- on a hill or mountain that stands at least 30 metres above the general terrain = less fog
- high ridge or mountain with a 300 metre cliff = almost no fog, ever (the cool moist air will slide off into the valley).
- a high site with cliffs on the western side = poor seeing due to thermals, the late afternoon sun will heat the cliff face and it will take many hours before it cools down. This applies winter and summer.

Lastly, if you must use an app on your iDevice, the only ones worth using are the ones that use the BOM data directly such as Oz Weather (this accesses the readings from the Automatic Weather Stations every 10 minutes). The apps that use data from sources such as Wunderground or Yahoo are all rubbish, as is the Seabreeze website.