Next Chance for Aurora – Friday Jan 30, 2015

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Current runs of the WAS-Enlil model are showing a conditions that might be conducive to G1 geomagnetic storming this Friday. Solar winds will be high, and plasma density is expected to be moderate. Together, these imply the magnetosphere will be susceptible to, and more reactive to, arriving solar storms and geomagnetic disturbances. Earth will be on the boundary between very strong and moderate solar winds which might elevate the probability of those disturbances happening.

These elevated conditions are related to the same large Southern Hemisphere coronal hole that has been occasionally sending high speed wind speeds toward Earth over the last month. On the current WSA-Enlil run, solar winds are predicted to be 500-600 km/s. This speed implies that the material leaving the sun will arrive at Earth about 3 days later. Today is the 27th, so Earth-facing material ejected from the Sun today will arrive on the 30th. Here’s an image of the Coronal hole as of 6:00pm EST on Jan 27:

Southern Hemisphere Coronal Hole in AIA 211
Large Coronal Hole in Southern Hemisphere continues to impact Earth

Notice the hook shape dark area approaching the midpoint. It is farther North that the rest of the coronal hole. That means that high speed wind stream it is producing will be closer to the Earth-Sun plane. The high speed winds are also evident on the WSA-Enlil run. Here, we’ve freeze-framed roughly noon on the 30th. The orange area in the lower portion, and the green line in the “Radial Velocity” chart show wind speeds in excess of 500 km/s. (click for a bigger image)

WSA-Enlil output showing high speed wind
High speed winds of 500 km/s arrive at earth at noon on January 30, 2015

See our most recent post on NLN discusses how to read the WSA-Enlil output. It actually appears solar wind speed will be high for several days, the 30th is the only day showing a concurrent elevated plasma density. Thus, as of now, Friday appears to be the best chance for Northern Lights.

Plasma density may still become elevated later in the high solar winds period. An eruptive flare from active regions 2268, 2273, or 2271 in the next day could also send a solar storm towards Earth. All three regions have been growing in size and complexity over the last 24 hours. A filament eruption could also trigger a geomagnetic events. If any of those events happen, the already high wind speed could magnify the impact of even a wimpy solar storm arrival.

The predicted combination of high solar wind speed, moderate solar density, and being on the threshold between moderate and high solar wind all elevate the chances for geomagnetic storming producing Aurora on Earth on January 30. The wild card remains the Bz component, if it shifts southward, we may be in for a show. If it stays stubbornly north, we won’t see an Aurora. NLN is predicting KP of 3.6-4 with a possibility of KP=5 (G1 storming) Friday, with a chance for G1 storming through Monday if there are eruptive events. You can monitor a live chart of the current predicted KP on Northern Lights Now.

Happy hunting!