This is a 30-40 minute forecast and shows the probability of OVERHEAD aurora from NOAA (not probability of seeing on the horizon).
The colours of the Aurora are colour coded based on the probability of seeing the Aurora OVERHEAD at a location (see bottom left of map for key)
This is a guide only. Auroras may or may not be visible. Visibility depends on other data such as Bz, wind speed and density (see further down this page for other data).
This chart is from NOAA. It updates every minute to show the current planetary Kp index.
Look for a red bar as this means the Kp levels are high, the Kp number can be found at the left of the chart.
Yellow means there is a disturbance and green means low activity
This graph is from the NOAA.
A simple explanation and what to look for in the plots:
Bz (Red Line)
The most important things to look for in the graph. The Bz MUST be south for a good display to take place. Moderate and Strong South is a good indicator that the Aurora may be seen from our location.
-10 moderate South
-20 Strong South
Density - Dense solar winds can help produce a good Aurora storm. A value above 20p/cm³ helps to contribute to an Aurora storm, but as this isn't as important as Bz and Speed a storm could develop with lower density readings.
<10 low density
40> high density
60> very high density
Speed - for our area a speed of more than 700 km/sec helps. This does depend on the Bz though, if this is moderate - strong South it could cause Aurora without this figure being met.
<400 normal speed
500> moderately high speed
700> very high speed
900> very high speed