Category Archives: Alerts

NLN Aurora Brief – November 3, 2015

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Aurora Brief Volume 3, Number 1 of 7
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Aurora Storm Update

The anticipated high wind stream associated with the coronal hole are later that expected. NOAA forecaster had been anticipated to arrive mid-day on November second but as of this writing, only the leading edges of the wind stream have arrived at the ACE satellites. They are still predicting that when the winds arrive they will be in excess of 800 km/s and when they do they could last as long as 12-18 hours. This should be strong enough and long enough for an extended period of northern lights activity.

Current today/tomorrow aurora forecast from NLN 3-day forecast
Current today/tomorrow aurora forecast from NLN 3-day forecast

Earlier on November 2nd, there was a shock passage measured at ace satellites with a very typical pattern. First the Bt increased from around 3-4 to 10 nT, next the proton density increased by almost 8 fold in three waves. On the third wave, the solar wind speed increased from 325 km/s to 410 km/s. Shortly after this (though not captured in the image below), the Bz shifted south. This was a short lived wave, but when the main high speed stream arrives, it may have a similar pattern. Graphs in this image are form SpaceWeatherLive

Space weather data snapshot from just after initial shock arrives at ACE satellites
Space weather data snapshot from just after initial shock arrives at ACE satellites

On the Sun:

Active Region 2443 has regained it’s delta spot and is not classified Beta-Delta. It produced several flares over the period. One flare late in the Nov 1 period laucnhed a CME that was determined to be south and East (in front) of the Earth-Sun line. This region is now in the Earth strike zone and has potential to produce more flares and CME eruptions.

AR 2443 in SDO colorized magnetogram has gained a delta spot and has flaring potential
AR 2443 in SDO colorized magnetogram has gained a delta spot and has flaring potential

Happy Hunting

G2 Aurora Storming Predicted for Oct 8 2015

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SWPC has issued a G2 geomagnetic storm watch for October 7th and 8th and a G1 geomagnetic storm watch for October 9th. A positive polarity equatorial coronal hole will be producing a high speed solar wind that should be arriving late on Wednesday October 7th. On the previous rotation (Sept 8) this coronal hole produced a 2 day period of G1 and G2 storming. Here’s an image of the coronal hole on the previous rotation, and on the current rotation (Click for larger view):

Coronal hole images from last rotation and this rotation
Comparison of Sept 8 Coronal hole rotation to Oct 6

Coronal holes on the equator of the sun take roughly 27 days to make a full rotation. During that time they are constantly changing and evolving. It is clear this coronal hole – the dark areas on the AIA 211 images above – has become larger. It is generaly a safe bet that if the previous rotation created a strong solar stream, the current rotation will as well.

Like on the last rotation, the predicted storm is coming at a good time for aurora hunters. The Moon will be in a waning crescent phase, so there shouldn’t be much light pollution from the moon. For viewers in the northern hemisphere there is between 30 and 90 minutes of additional dark hours as the nights are longer and days are shorter since the last rotation. This is what the phase of the moon should look like:

Moon phases during predicted Aurora period
MoonPhases for Oct 7-9

Predicting the timing of Aurora that come from a coronal holes is a little easier than that from CMEs. It is hard to determine the speed and orientation of a CME, but with a coronal hole there is a narrower window. That said, predicting the exact timing of any geomagetic storm is difficult, and predictions can be off by as much as 6-12 hours. As of this writing, the current timeline calls for a peak of the G2 storming to happen starting at the end of October 7 and continuing through the early hours of Oct 8 – with G1 storming continuing for up to 6 more hours. For the East Coast Time zone, this means Wednesday evening from sunset through 3:00-6:00AM. NLN’s current infographic for the timing of the storm’s arrival:

NLN aurora prediction clock showing predicted storm arrival
Aurora timelines as of 10/6/2015

The predicted timelines are updated twice daily, you can always find them on NLN’s three-day forecast page. You can also keep an eye on the current and near-term predicted KP and the ovation auroral oval on the NLN Current Current KP Real-Time page.

Happy Hunting!

Aurora Dream Week Continues G2/G1 Watch Sept 11 and 12

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This has been a dream week for aurora chasers. There have has been G2 storming four of the last five days. SWPC has predicted that it will continue today and tomorrow as well. A G2 watch is up for today (September 11, 2015), and tomorrow. This storm watch is posted in anticipation of the arrival of a coronal hole high speed stream. Here is the watch graphic from SWPC:

SWPC predicts G2 storming for September 11, 2015
SWPC predicts G2 storming for September 11, 2015

For timing, the expected peak will come overnight in Europe and just as evening is approaching on the East coast. You can see in the NLN 3-day forecast clock the storm is expected to start with G2 storming, then taper to G1 for the next 6-12 hours. In addition to this being perfectly timed for a Friday night – most of us don’t have work the next day – it is falling when the moon is nearly new, so it should be very dark.

Timing on the expected G2 storming Sept 11 and 12, 2015
Timing on the expected G2 storming Sept 11 and 12, 2015

The source of this storm is a coronal hole that was pointed directly at Earth on Sept 8. The size and shape of the hold suggest this should be a good show.

SDO image of large coronal hole
Coronal hole that could potentially impact Earth later this week

As always with these watches, there is a chance we might not get any aurora from this storm. We saw a period of high solar wind speed earlier in the day, and that may have been the entire storm. Space weather scientists and forecasters don’t have enough data coming from satellites and ground based observations to really make the models 100% accurate. If you go out tonight, and there aren’t any aurora, don’t fret, enjoy the stars and know there will be more opportunities.

Happy Hunting!