Northern Lights Now – Just a couple days before the 2017 total eclipse in the United States, there will be another exciting astonomical event. There is a chance for Aurora on August 17 and 18. The Space Weather Prediction Center (SWPC) has issued a G1 geomagnetic storm watch for Wednesday and Thursday. Global aurora activity levels could reach KP=5 on the 0-9 scale.
The expected activity is the result of a activity from a solar sector boundary crossing during high speed solar wind stream arriving from a coronal hole. The northern hemisphere coronal hole (below) pointed towards Earth on August 15th is releasing solar winds in excess of 650 km/s. The winds, and the plasma and solar particles carried on them will start to arrive early on 8/17
Embedded in the solar wind there will be disturbance along the solar sector boundary. This is basically a line on the in space between a positively charged region and a negatively charged region. As the boundary passes Earth, there will be enhanced geomagnetic activity leading to Northern Lights.
Northern Lights Now – A large polar-connected coronal hole will bring high speed solar wind to Earth starting August 4th and SWPC has posted a G2 geomagnetic storm watch. The watch means it is possible that aurora activity as measured by KP may reach 5.67 during the August 4th UTC day (from 8pm EST on 8/3 through 8pm EST on 8/4). The watch period extends into August 5th at a slightly lower activity level with G1 storming predicted.
The coronal hole responsible for this activity is large. It extends from the polar region to the Southern Hemisphere of the Sun:
Earth is expected to travel through the area of high speed solar winds sometime on Friday. Any disturbances carried on the wind stream with a negative oriented Bz could make for strong aurora activity. Keep any eye on the solar wind data, there should be a period of increased activity in Bt and Bz before the actual arrival.
The current timing and forecast for this storm calls for the G1 and G2 storming late on the 4th followed by G1 storming through midday on the 5th as winds subside. As always, these forecasts can be +/-12 hours, so the best bet is to keep an eye on the data or the Northern Lights Now Twitter feed, to know when it is best to go out.
The Moon is waxing gibbous – which means it will be visible and bright in the evening and set after midnight. The best aurora viewing times will be in the wee hours after the Moon sets.
Northern Lights Now – There is an extended period of active aurora predicted for the third week of May 2016. NLN is going into live-blog mode to provide updates as the storm unfolds. Please check this page often.
Some helpful links to us to watch the storms unfold:
Live KP: use this to see the KP over the next 45 or so minutes to time your trip outside
AuroraCast: NLN’s visualization of the current SWPC 3-day forecast
DSCOVR Solar Wind: Raw data that feeds the live KP model – be super science and predict earlier than the models!
NLN Live Blog Update – Sat May 20, 11:30 UTC (03:30 EST)
Thanks for following along the live blog! There may be some residual activity as solar wind is still high, but the storm appears to be over. Here’s a nice timelapse from @isaac_diener of last night’s activity.
NLN Live Blog Update – Sat May 20, 03:15 UTC (23:15 EST)
As anticipated, the third part of this storm is producing the most activity. But it hasn’t been much so far with geomagnetic activity just exceeding the KP=4 level. Solar winds are looking good, so there is still a chance for G1 storming in the next 3-5 hours.
Did you notice the short term KP forecast is behind? Occasionally the source data, which comes from a neural network run by the space weather prediction center goes offline. When it does, predictions come back from the model as -1. Clearly, the level of activity is not negative!
NLN Live Blog Update – Fri May 19, 13:30 UTC (09:30 EST)
Earth is now in the coronal hole high speed wind. Wind speeds are approaching 500km/s. Over the last 45 minutes, Bz has dipped south. If this keeps up, the KP should tick back up.
NLN Live Blog Update – Fri May 19, 01:45 UTC (21:45 EST)
With the start of 5/19 UTC, the G2 storm watch is now in effect as part three of this complex set of storms is expected to arrive. Over the last hour proton density has been steadily increasing. This is an indication that the CIR is about to arrive. It will be followed by high speed winds from the coronal hole. It should be clear in the next 3-5 hours if there will be strong aurora from this storm, of if it is another bust like the first two parts of this week’s activity. Aurora hunters world wide remain optimistic!
NLN Live Blog Update – Thurs May 18, 12:30 UTC (08:30 EST)
Overnight there was a brief period of northern lights between midnight and 1 am EST while the Bz was oriented southward. Since then, KP has been between 3 and 4. This was long enough for some aurora hunters to capture the show. Here are a couple clips from the NLN Twitter feed. Thanks for sharing!
NLN Live Blog Update – Thurs May 18, 04:15 UTC (00:15 EST)
Finally! Wing Kp model is calling for KP=5.00 shortly. Bz has turned south and persisted for over 2 hours, it has been hovering around -5nT for the last 30 minutes. That is strong enough to make the models predict aurora!
NLN Live Blog Update – Thurs May 18, 01:00 UTC (21:00 EST)
Another quiet day. The maximum measured KP was 2.67. It appears the expected CME went to the South of Earth and we won’t be seeing any impact from it. SWPC updated the watches. They have cancelled the G2 watch for the 17th and downgraded the watch on the 18th to a G1 watch. They did maintain the G2 watch for the 19th and extend a new G1 watch to the 20th.
The third part of the expected storm should start to impact Earth late on the 18th (UTC) as Earth crosses a solar sector boundary and a co-rotating interactive boundary in advance of the wind from the next coronal hole. Then activity should pick up on the 19th as Earth enters the high speed wind from the coronal hole. This is illustrated in the WSA-Enlil (How to read Enlil ) below. Earth is the green filled circle on each of the graphs. At the top, see that density is high as Earth is in the SSBC, on the lower portion, see that wind speeds are picking up as Earth enters the wind stream.
NLN Live Blog Update – Wed May 17, 11:00 UTC (07:00 EST)
Solar wind speeds have been slowly decreasing overnight as the influence from the first coronal hole wanes. Winds speeds have dropped to around 500km/s. Bz has been oriented southward (negative) for over 2 hours now. The combination what is responsible for pushing short-term Kp predictions to between 3 and 4. Even with the strength of the field low, extended periods of Bz like this can lead to aurora. We aren’t expecting any amazing jumps in Kp until other solar wind parameters become more favorable.
The next feature that may become evident in this storm is the arrival or glancing blow from the CME that launched late on May 13. The material from the CME is slow moving and mostly to the south of Earth. SWPC models are indicating some of the material may have been on the Earth-Sun plane. Here is a snapshot of the CME in lasco C2 and C3 imagery. It is faint, but the CME can be seen as a “cloud” emanating from the bottom right of the Sun at starting around the 21:00 timestamp in C2 (orange/red) and the 22:30 timestamp in C3 (blue)
NLN Live Blog Update – Wed May 17, 03:45 UTC (11:45 EST)
As of midnight, a G2 storm watch is now in effect. SWPC extended the watch an additional 24 hours through May 19. The 19th currently looks like it will be the most active day this week. G1 and G2 storming is predicted for all but one 3-hour period during the that day. Here is the NLN AuroraCast showing the predicted KP for each 3-hour time period over the next three days.
For the first day of this event, measured KP peaked at 3.00. Storm levels did not reach the G1 threshold.
NLN Live Blog Update – Tue May 16, 21:00 UTC (17:00 EST)
Despite a G1 storm watch posted for today, it doesn’t appear KP levels will reach 4.67 today. Solar wind speed have increased as a result of the coronal hole high speed stream and have been above 500km/s for most of the day. Solar winds reached a peak speed of 678km/s early in the UTC day, but have since declined. It is not unusual that a predicted G1 storm does not live up to expectations, there is plenty of activity predicted for the next 2 days and probably more. Stay tuned.