Northern Lights Now – The Space Weather Prediction Center in Boulder Colorado has issued a G1 storm watch for October 11-12 indicating the potential for KP values at or above 5 and active aurora. This is due to the expected high speed solar wind coming from a large northern hemisphere coronal hole.
Models, such as the WSA-Enlil below, are predicting that the first phase of the storm should start midday on Tuesday as plasma densities rise to around 15 p/cm3. 6-12 hours later, solar wind should pick up and may reach 550 km/s. The coronal hole covers a large area longitudinally, so once the wind speed readings increase, they may remain elevated for over three days. It would not be surprising to see the G1 watch extended into a third day.
As of this writing, the periods of KP=5 and above are predicted to start midday on Oct 11 and continue on and off throughout Oct 12.