CH HSS sparks G1 – Minor geomagnetic storm, G2 – Moderate warning

A recurrent, positive polarity coronal hole high speed stream (CH HSS) is affecting our planet since September 23, sparking active to G1 – Minor geomagnetic storm conditions. A G2 – Moderate geomagnetic storm warning was issued at 08:07 UTC today.

In 24 hours to 00:30 UTC on September 24, solar wind parameters reflected slightly elevated CH HSS conditions.

Total magnetic field strength was mostly 4 to 6 nT before increasing to near 8nT.

The Bz component generally varied between +3 to -5 nT. Solar wind speeds increased from near 350 km/s to 465 km/s. Phi angle was predominately in a positive orientation.

The geomagnetic K-index of 5 threshold was reached at 07:41 UTC.

The solar wind environment is expected to reflect CH HSS conditions through September 26.

Synoptic map courtesy SWPC

Meanwhile, solar activity is at very low levels.

A new, but so far benign, active region was numbered yesterday as AR 2773, breaking the stretch of 33 spotless days.

From January 1 to September 24, 2020, the Sun has been spotless for 189 days — or 71%. Although we see signs of the new solar cycle — Solar Cycle 25 — we are still experiencing very deep solar minimum and significantly increased cosmic radiation.

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Space Weather Message Code: ALTK05
Serial Number: 1298
Issue Time: 2020 Sep 24 0747 UTC

ALERT: Geomagnetic K-index of 5
Threshold Reached: 2020 Sep 24 0741 UTC
Synoptic Period: 0600-0900 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.

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Space Weather Message Code: WARK06
Serial Number: 437
Issue Time: 2020 Sep 24 0807 UTC

WARNING: Geomagnetic K-Index of 6 expected
Valid From: 2020 Sep 24 0806 UTC
Valid To: 2020 Sep 24 1200 UTC
Warning Condition: Onset
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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Featured image credit: SWPC