Tag Archives: northern lights

Surprise G1 Aurora Storm on August 23/24 2016

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Northern Lights Now – The high speed wind stream from a coronal hole that was pointed towards Earth on August 21 is arriving with a stronger than expected impact. As a result KP values are reflecting an ongoing G1 level storm. The storm has allowed aurora hunters to see the lights in Denmark and Sweden and in the US in Maine. The initial forecasts only called for a period of enhanced solar wind speeds and a max KP value of 4. This is the coronal hole that is currently impacting Earth as it looked on August 21:

Aug 21 coronal hole produces Aurora and G1 storming on Aug 23rd and 24th
Aug 21 coronal hole produces Aurora and G1 storming on Aug 23rd and 24th

The high speed wind arrived earlier than expected, and stronger than expected. As an added bonus for our readers, it arrived with a period of several hours of southern oriented Bz. When the Bz component of the magnetic fields have negative readings, it means aurora are more likely. As this storm was building, it arrived with a period of over 4 hours where the Bz was negative from about 16:00-20:00 UTC. At points it was strongly negative with readings of -10Bz. This is the image of NLN’s accumulated aurora power chart from the peak of the first wave of the storm:

DISOVR accumulate Aurora power Graph from the peak of the first wave of the storm
DISOVR accumulate Aurora power Graph from the peak of the first wave of the storm

There are a couple interesting things to point out in that graph:

  • At the time of the snapshot the total magnetic field (Bt) had been strong for over 12 hours, and very strong in the last hour.
  • Wind speeds had really only just started picking up in the last 2 hours.
  • The real kicker was that Bz had been negative for over 2 hours and was as strong at -10nT (very strong) for 5 minutes.

It is rare that a coronal hole triggers all 4 of these metrics at the same time on this chart. When they are all there, it’s a good sign for aurora hunters.

Here are some of the shots that we saw come in on Twitter:

Some of the first Images of this storm came from Denmark by @ADphotography24:

Another from Sweden by Göran Strand (Also the first wave of this storm):

From Rob Write (@RobWrightImages) on the Southern Maine Coast (in the second wave of this storm):

As of 3:20 UTC August 24 at the time of this writing, the storm has subsided a little. It looks like there could be anywhere from 3-6 more hours of enhanced solar wind speeds, and at any point the Bz could dip back south. If it does, Aurora hunters could be in for more of a treat. Keep an eye on the solar wind data.

Also, there is another coronal hole rotating towards Earth that has a history of producing good aurora. This could impact Earth on Aug 30th and 31st…. stay tuned!

Happy Hunting

G2 Aurora storming predicted for August 2nd and August 3rd 2016

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Northern Lights Now – SWPC has issued two geomagnetic storm watches for G2 storming (KP=6+) on August 2nd and G1 storming (KP=5+) on August 3rd. These watches are the result of a pair of solar features that will impact Earth starting midday UTC on August 2nd. The NLN AuroraCast shows the current predicted timing for the timing. As always, these can be within +/- 6 hours:

Please visit NLN’s live blog of this storm and follow out Twitter feed for the most up-to-date information.

NLN AuroraCast shows the expected timing of the G1 and G2 storming for Aug 2nd and 3rd
NLN AuroraCast shows the expected timing of the G1 and G2 storming for Aug 2nd and 3rd

The first solar event that will impact Earth is the arrival of a very slow moving CME (Coronal Mass Ejection) that was launched during the July 28th filament eruption. The eruption happened almost dead center (near N01E06) on the solar disk. The associated CME was estimated to be travelling at 125-150 km/s. At that speed, it could take as many as 7 days for the CME to arrive at Earth, but it should be pushed by the ambient solar wind to 350 km/s or so. Then, an even higher wind from a coronal hole high speed wind stream should push it even faster to 600-650 km/s. There are several factors making the timing on this forecast complex – current models show the CME arriving midday to late August 2nd, 5 days after it’s launch.

In the animated GIF below watch the filament eruption in a composite of AIA 211, 193 and 171 wavelengths. These frames are about 14 hours of images taken by the Solar Dynamic Observatory (SDO) cameras. Note that just to the east (left) of the eruption, the coronal hole rotating into center disk is visible as a darker area:

AnimatedGIF of July 28th filament eruption responsible for the G2 aurora watch on Aug 2
AnimatedGIF of July 28th filament eruption responsible for the G2 aurora watch on Aug 2

The second feature is a large coronal hole that rotated into geoeffective position on July 31. The high speed stream from this CH measured at STEREO Ahead indicated that winds could reach 650-750 km/s at L1. This very strong wind will likely start impacting Earth either with or just after the CME arrives. If it “pushes” the particles in the CME, they will arrive at the leading edge of the shock. Due to the elongated shape of the CH, the period of elevated winds could be extended in duration. Here is an image of the coronal hole from SDO in AIA 211 from July 31 as it rotated toward Earth:

Coronal hole in AIA 211 from SDO on July 31
Coronal hole in AIA 211 from SDO on July 31

Together these storms have the potential to arrive with a strong shock and an extended period of high solar wind and active geomagnetic conditions. If they do, it should be a very good couple of nights for aurora hunters worldwide. As an added bonus, the Moon will be waxing just past new, so skies should be dark.

Happy Hunting!

Aurora Possible July 20 and 21

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Northern Lights Now – There is a slight chance for an aurora display on July 20 and July 21 UTC. The most likely times are in the evening, just after sunset and before moonrise, across the Northern United States. The chances aurora may be visible are higher at this time because a cloud of magnetically charged gas is moving toward Earth after an eruption on the Sun on Sunday. The chances are only slight because the cloud is moving slowly and when it arrives it may not have enough magnetic charge to activate the aurora bands. It will also be hard to see any aurora because the Moon will be full or near-full, which will make the sky fairly bright overnight.

That said – keep your cameras ready because there’s a chance!

Happy Hunting