Aurora set to appear over Montana Sunday night

Update: 11:35 p.m: 

Aurora conditions continue to diminish tonight. It's unlikely that the aurora will be visible in many areas of Montana without using long exposure photography. Here's the latest forecast from the SWPC for around midnight. 

Update 9:30 p.m:

Kp has fallen dramatically in the past three hours. There are reports of extremely faint Aurora activity in New England. Here's the latest forecast for Montana tonight. Kp values on this graphic are marked by the colored lines.

Original story: 

The Aurora Borealis, also known as the Northern Lights, will make an appearance over Montana as a solar storm continues to move past our planet. Activity is waning as we approach 8 p.m. local time, but because of clear skies tonight there still may be a chance to spot them. 

The storm began on July 14th with what's known as a Coronal Mass Ejection, or CME, began to trek towards Earth. CMEs are explosions of plasma and charged particles from the sun that are truly enormous. This CME captured on camera in 2000 is larger than the sun itself! 

The July 14th CME arrived a little earlier than space weather forecasters expected, first slamming into the upper atmosphere and Earth's magnetic field at around 11:15 p.m. Mountain Daylight Time on July 15th. According to the U.S. Space Weather Prediction Center, or SWPC, some slower CMEs can take 24 to 36 hours to pass by our planet. As of 6 p.m. local time we've been moving through the CME for about 18 to 20 hours. You can see that in this chart of what's called the K-index, or Kp as it's more commonly known to people who go chasing the Aurora. Kp is a simple measurement of the power of geomagnetic storms. 

CMEs and other types of space weather can impact power grids, radio, and satellites across the entire globe. You can read more about how the SWPC categorizes geomagnetic storms here

Kp for this storm has been at a 5 or a 6 for around 15 hours. It's likely that this storm is at least halfway over. Should the Kp remain at 5 or 6 for most of the night, most of Montana should be able to see the Northern Lights, even if it's low on the horizon in southern parts of the state.


In far southwest Montana you'll probably have to look really low on the horizon to see anything, while viewing should be fairly east along the Hi-Line. Either way, make sure you get away from light pollution from towns and cities so you get the best view. 

The SWPC forecast has the Kp staying at a 5 or 6 through midnight, before declining to a maximum Kp of 5 between midnight and 6 a.m. early Monday morning. Between 11 p.m. and 3 a.m. will likely be the best time to watch in case the storm ends earlier than expected. If the Kp falls below 5, it will be difficult for many areas other than right near the Canada border to see the Aurora. If you go out to find the Aurora tonight be sure to send us your pictures and videos! 


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