National Weather Service United States Department of Commerce

 On the night of November 7th and into the early morning of the 8th, the inland northwest was showered with a spectacular display of Northern Lights or Aurora Borealis.

  The Aurora is defined as glowing, visual phenomenon associated with geomagnetic activity, which occurs mainly in the high-latitude night sky. The glow comes from pulses of solar geomagnetic energy bombarding or exciting magnetically charged particles in the ionosphere, roughly 100 to 250km above the ground. 

   Although eastern Washington and north Idaho do not commonly witness these fascinating light shows, they typically happen a handful of times during the year. The rarity of the events in the inland northwest can be attributed to our mid-latitude location and the amount of cloudiness we typically see.


 The electromagnetic energy which produces the aurora phenomena is measured by the NOAA Space Center, utilizing an index termed the Kp Index. Although this is a difficult index to calculate, the resultant values correlate to the chances of witnessing an aurora at a given location. 

   The map at the left shows what the minimum value of the Kp index needs to be to at your location in order to possibly witness the aurora. A value of 5 or 6 (or greater ) suggests that most of the inland northwest could possibly witness auroral activity. Of course factors such as moonlight, city light pollution, and cloud cover will impact the visibility of the auroral activity.

The night of the auroral activity featured a Kp index value of 10 with reports of the northern lights being seen as far south as Oklahoma. The graph on the right corresponds to the Kp index levels over a 72 hour period. The times are in Universal Time Coordinates, which run 7 hours ahead of Pacific Standard Time.