2ND UPDATE: Auroras are indeed being observed. (I myself am a bit too far south and skies are hazy, making the moonlight blinding; but I am reading reports from northern Europe.)
UPDATE: Something has happened at the ACE satellite around 2300 UTC (0100 Europe time, 7 pm New York time. See the plot added to the bottom of this post.
———-
Still waiting for a possible outbreak of auroras (northern/southern lights) tonight; a tremendous blast from the Sun, launched from a sunspot two days ago, is believed likely to make a glancing impact on the Earth, and to do so within the next 12 hours or so. That means a possibility of bright northern lights tonight if you’re north of, say, New York City’s latitude.
BUT always keep in mind that forecasting auroras is part science, part art, part luck. Our chances are decent, but the forecast can always be wrong.
As far as timing, the best way to monitor what’s going on, I’ve found, is to use https://www.swpc.noaa.gov/products/ace-real-time-solar-wind and look for sudden activity in multiple data channels. If that happens, then the ACE satellite (about a million miles away) has detected a sudden change in the solar wind, and a geomagnetic storm is likely to start at Earth within an hour or so.
Whether you will see auroras or not during the storm depends on how powerful it is, which determines how far from the poles the auroras will reach and how bright they will be. While the forecast is for a strong storm, we’ll just have to see…
At 2300 UTC (about one hour before this posting) you can see jumps occurred in many channels below. That means that the solar storm may begin right around now (0000 UTC, 8 pm New York Time)