[Phys-L] aurora alert : Monday evening

[John Denker <jsd@av8n.com>]

If you are in the northern tier of US states, you have a decent chance of 
seeing an aurora Monday night into Tuesday morning, September 18th-19th.

1) Check the weather. Places from Albany eastward are forecast to be cloudy, 
but who knows, you might get lucky. Michigan, Wisconsin, and maybe even Seattle 
are forecast to be clear. Of course Alaska is in a category of its own.

2) The new moon is nothing to worry about.

3) The NOAA aurora forecast should not be taken too seriously. It is commonly 
off by an entire unit in one direction or the other. If the forecast is 6 and 
the actual event is 7, you could see quite a memorable show.

I have plotted the latest NOAA forecasts here:
Maine:  https://av8n.com/physics/img48/aurora-forecasts-me.png
Seattle: https://av8n.com/physics/img48/aurora-forecasts-sea.png

That includes an indication of the local hours of darkness and mooniness at the 
chosen location. For other locations, you can interpolate. (If you need a 
personalized localized version, I can easily generate it.) By dark I mean really 
dark, i.e. astronomical dark, i.e. sun 18° below the horizon.

For further information, see
https://www.swpc.noaa.gov/content/aurora-dashboard-experimental

The panels on that dashboard will expand if you click on them.