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G3 – Strong geomagnetic storm levels reached

g3-strong-geomagnetic-storm-september-28-2017

A recurrent, polar-connected, positive-polarity coronal hole is affecting our planet since September 27. G1 – Minor geomagnetic storm levels were reached at 08:48 UTC on September 27, followed by G2 – Moderate levels at 20:24 UTC and then increased to G3 – Strong levels by 05:59 UTC on September 28, 2017.

Under G3 – Strong geomagnetic storm, the area of impact is primarily poleward of 50 degrees Geomagnetic Latitude. Power system voltage irregularities are possible, false alarms may be triggered on some protection devices. Spacecraft systems may experience surface charging; increased drag on low Earth-orbit satellites and orientation problems may occur. Intermittent satellite navigation (GPS) problems, including loss-of-lock and increased range error may occur. HF (high frequency) radio may be intermittent and aurora may be seen as low as Pennsylvania to Iowa to Oregon.

The solar wind environment is expected to remain enhanced for the next three days due to ongoing CH HSS effects.

Over the past 24 hours, the geomagnetic field reached G1 – Minor storm levels in the 06:00 – 09:00 UTC synoptic period on September 27 due to Co-rotating Interaction Region (CIR) and recurrent, polar-connected, positive polarity CH HSS influences. G2 – Moderate levels were reached by 20:24 UTC on September 27 and increased to G3 – Strong by 05:59 UTC on September 28.

G2 – Moderate storm levels, with possible isolated periods of G3 – Strong levels, are expected on September 28 as a result of an ongoing positive polarity CH HSS. G1 – Minor storm levels are likely on September 29 as CH HSS effects persist. Mostly active geomagnetic conditions, with a chance for G1 (Minor) levels being reached, are expected on September 30.

SWX overview 3-day September 28, 20173-hour K-indices for last 7 days

Coronal Hole - September 25, 2017

Coronal Hole - September 25, 2017

SWPC alerts, watches and warnings

Space Weather Message Code: ALTK05
Serial Number: 1171
Issue Time: 2017 Sep 28 0636 UTC

ALERT: Geomagnetic K-index of 5
Threshold Reached: 2017 Sep 28 0635 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.

***

Space Weather Message Code: ALTK07
Serial Number: 110
Issue Time: 2017 Sep 28 0600 UTC

ALERT: Geomagnetic K-index of 7
Threshold Reached: 2017 Sep 28 0559 UTC

Synoptic Period: 0300-0600 UTC

Active Warning: Yes
NOAA Scale: G3 – Strong

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

Potential Impacts: Area of impact primarily poleward of 50 degrees Geomagnetic Latitude.
Induced Currents – Power system voltage irregularities possible, false alarms may be triggered on some protection devices.
Spacecraft – Systems may experience surface charging; increased drag on low Earth-orbit satellites and orientation problems may occur.
Navigation – Intermittent satellite navigation (GPS) problems, including loss-of-lock and increased range error may occur.
Radio – HF (high frequency) radio may be intermittent.
Aurora – Aurora may be seen as low as Pennsylvania to Iowa to Oregon.

***

Space Weather Message Code: WARK07
Serial Number: 73
Issue Time: 2017 Sep 28 0537 UTC

WARNING: Geomagnetic K-index of 7 or greater expected
Valid From: 2017 Sep 28 0536 UTC
Valid To: 2017 Sep 28 0900 UTC
Warning Condition: Onset
NOAA Scale: G3 or greater – Strong to Extreme

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

Potential Impacts: Area of impact primarily poleward of 50 degrees Geomagnetic Latitude.
Induced Currents – Power system voltage irregularities possible, false alarms may be triggered on some protection devices.
Spacecraft – Systems may experience surface charging; increased drag on low Earth-orbit satellites and orientation problems may occur.
Navigation – Intermittent satellite navigation (GPS) problems, including loss-of-lock and increased range error may occur.
Radio – HF (high frequency) radio may be intermittent.
Aurora – Aurora may be seen as low as Pennsylvania to Iowa to Oregon.

***

Space Weather Message Code: ALTK06
Serial Number: 451
Issue Time: 2017 Sep 28 0509 UTC

ALERT: Geomagnetic K-index of 6
Threshold Reached: 2017 Sep 28 0508 UTC
Synoptic Period: 0300-0600 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.

***

Space Weather Message Code: ALTK05
Serial Number: 1170
Issue Time: 2017 Sep 28 0412 UTC

ALERT: Geomagnetic K-index of 5
Threshold Reached: 2017 Sep 28 0411 UTC
Synoptic Period: 0300-0600 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.

***

Space Weather Message Code: ALTK06
Serial Number: 450
Issue Time: 2017 Sep 28 0303 UTC

ALERT: Geomagnetic K-index of 6
Threshold Reached: 2017 Sep 28 0259 UTC
Synoptic Period: 0000-0300 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.

***

Space Weather Message Code: WARK04
Serial Number: 3331
Issue Time: 2017 Sep 28 0245 UTC

EXTENDED WARNING: Geomagnetic K-index of 4 expected
Extension to Serial Number: 3330
Valid From: 2017 Sep 27 0610 UTC
Now Valid Until: 2017 Sep 28 1800 UTC
Warning Condition: Persistence

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

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents – Weak power grid fluctuations can occur.
Aurora – Aurora may be visible at high latitudes such as Canada and Alaska.

***

Space Weather Message Code: WARK06
Serial Number: 405
Issue Time: 2017 Sep 28 0245 UTC

EXTENDED WARNING: Geomagnetic K-Index of 6 expected
Extension to Serial Number: 404
Valid From: 2017 Sep 27 2012 UTC
Now Valid Until: 2017 Sep 28 0900 UTC
Warning Condition: Persistence

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.

***

Space Weather Message Code: WARK05
Serial Number: 1411
Issue Time: 2017 Sep 28 0245 UTC

EXTENDED WARNING: Geomagnetic K-index of 5 expected
Extension to Serial Number: 1410
Valid From: 2017 Sep 27 0749 UTC
Now Valid Until: 2017 Sep 28 1500 UTC
Warning Condition: Persistence

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.

***

Space Weather Message Code: ALTK05
Serial Number: 1169
Issue Time: 2017 Sep 28 0132 UTC

ALERT: Geomagnetic K-index of 5
Threshold Reached: 2017 Sep 28 0130 UTC
Synoptic Period: 0000-0300 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.

***

Space Weather Message Code: ALTK06
Serial Number: 449
Issue Time: 2017 Sep 27 2222 UTC

ALERT: Geomagnetic K-index of 6
Threshold Reached: 2017 Sep 27 2220 UTC
Synoptic Period: 2100-2400 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.

Featured image: Aurora in Big Valley, Alberta on September 28, 2017. Credit: Dan Tanner (via Twitter)

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