Geomagnetic storm reaching G2 – Moderate levels in progress

Geomagnetic storm reaching G2 – Moderate levels is currently in progress due to continuous influence from a positive polarity coronal hole. This influence will decrease over the next couple of days, however, the Coronal Mass Ejection (CME) associated with the M3.9 flare of November 9, 2015 is expected to arrive at Earth during the latter half of November 11 and fuel another round of geomagnetic storms.

Solar wind parameters, as measured by the ACE spacecraft, reflected the influence of a positive polarity coronal hole high speed stream (CH HSS) during the last 24 hours. Total magnetic field strength (Bt) peaked with values of 12 nT on November 9 at 19:26 UTC. Shortly afterwards they decreased and held steady between 7 to 10 nT throughout the rest of the period, SWPC said in their Forecast Discussion issued 12:30 UTC today.

The Bz component of magnetic field mostly varied, but had sustained periods of primarily southward orientation from 05:35 to 08:00 UTC and from 09:35 to 11:22 UTC on November 10.

Solar wind velocity was elevated due to the CH HSS. At the period's beginning the speeds varied between 450 and 500 km/s and steadily rose to a peak of 733 km/s by 10:42 UTC on November 10.

Image credit: NOAA/SWPC

Solar wind speeds are expected to remain enhanced throughout most of the day, and begin a gradual decline later on the night of November 10 to 11 due to continued, but waning CH HSS influence. During the later half of November 11, the CME from the M3 flare of November 9, is expected to increase solar wind velocity and increase the total interplanetary magnetic field (IMF) strength. Solar wind velocity and the total IMF strength is expected to remain elevated on into the early hours of November 12 due to the CME influences.

Geomagnetic K-index of 6 (G2 – Moderate geomagnetic storm) threshold was reached at 14:30 UTC on November 10. Area of impact is primarily estimated poleward of 55 degrees Geomagnetic Latitude. Power grid fluctuations are possible and high-latitude power systems may experience voltage alarms.

G2 conditions can trigger satellite orientation irregularities and increased drag on low Earth-orbit satellites. High frequency radio waves can fade at higher latitudes. Aurora events may be seen over New York to Wisconsin and Washington state.

The geomagnetic field is expected to fluctuate between active and minor storm (G1) levels with an isolated period of moderate (G2) storming on November 10 due to continued influence of the CH HSS. Active conditions are forecast to continue into November 11.

Later during the day of November 11, a glancing blow from the November 9 CME will likely impact Earth's magnetosphere with periods of G1 storm levels, which will probably continue into the early November 12.

SWPC Alerts

Space Weather Message Code: ALTK06
Serial Number: 383
Issue Time: 2015 Nov 10 1430 UTC

ALERT: Geomagnetic K-index of 6
Threshold Reached: 2015 Nov 10 1430 UTC
Synoptic Period: 1200-1500 UTC

Active Warning: Yes
NOAA Scale: G2 – Moderate

NOAA Space Weather Scale descriptions can be found at
www.swpc.noaa.gov/noaa-scales-explanation

Potential Impacts: Area of impact primarily poleward of 55 degrees Geomagnetic Latitude.
Induced Currents – Power grid fluctuations can occur. High-latitude power systems may experience voltage alarms.
Spacecraft – Satellite orientation irregularities may occur; increased drag on low Earth-orbit satellites is possible.
Radio – HF (high frequency) radio propagation can fade at higher latitudes.
Aurora – Aurora may be seen as low as New York to Wisconsin to Washington state.

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Space Weather Message Code: ALTK05
Serial Number: 890
Issue Time: 2015 Nov 10 1309 UTC

ALERT: Geomagnetic K-index of 5
Threshold Reached: 2015 Nov 10 1308 UTC
Synoptic Period: 1200-1500 UTC

Active Warning: Yes
NOAA Scale: G1 – Minor

NOAA Space Weather Scale descriptions can be found at
www.swpc.noaa.gov/noaa-scales-explanation

Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude.
Induced Currents – Weak power grid fluctuations can occur.
Spacecraft – Minor impact on satellite operations possible.
Aurora – Aurora may be visible at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.

Featured image: Aurora forecast for 17:30 UTC on November 10, 2015. Credit: NOAA SWPC