What produced the bright flashes tonight?

[screaming monk]

Awaiting an ISS flyby at 22:19 (EST), I, instead, witnessed two bright flashes near the zenith. The flashes were far brighter than anything else in the sky -- like a photographer's flash in the sky. There were no Iridium flares listed for this time, and so I wonder what these flashes were. They were bright white with no hint of red so I doubt they were bolides. Any idea as to what they were?
The duration of the flashes were maybe a fraction of a second at most. Other conditions:
Clear skies with a big moon off in the eastern skies.

 

[raj]

May be you saw a supernova or collusion of 2 stars .Man you are lucky. I will wait for tomorrow's news on "universe today" and various astronomy related web site.

 

[Quadrillian]

These flashes are caused by distant lightning.

There would be a large cumulonimbus aggregation many miles away. It will be down low to the horizon so will be invisible to you.

When there is a large lightning flash in the cloud, the lightning illuminates mist and dust in the air for many miles around. You don't see the lightning flash, but you see the sudden brightening of the aerosols that are always present in the atmosphere.

I have observed these flashes when the actual thunderstorm was 20 miles away according to the weather radar in my area.

Check the web site of you local weather bureau. They may have a weather radar within a hundred miles of you that will show all the rain producing cloud formations in your area.

Cheers!