Sudden enhancement in solar wind environment sparks G2 - Moderate geomagnetic storm

Sudden enhancement in solar wind environment sparks G2 - Moderate geomagnetic storm

G2 - Moderate geomagnetic storm conditions were observed early August 22, 2017 due to a sudden enhancement in solar wind environment. SWPC said conditions are not expected to increase any higher, with solar winds continuing to decrease as the day progresses.

Geomagnetic K-index of 6 (G2 - Moderate geomagnetic storm) threshold was reached at 02:59 UTC. Under G2 conditions, area of impact is primarily poleward of 55 degrees Geomagnetic Latitude. Power grid fluctuations can occur and high-latitude power systems may experience voltage alarms. Satellite orientation irregularities may occur, as well as increased drag on low Earth-orbit satellites. HF (high frequency) radio propagation can fade at higher levels and aurora may be seen as low as New York to Wisconsin to Washington state.

Geomagnetic K-index of 5 (G1 - Minor geomagnetic storm) threshold was reached at 05:35 UTC. Under G1 conditions, area of impact is primarily poleward of 60 degrees Geomagnetic Latitude. Weak power grid fluctuations can occur as well as minor impact on satellite operations. Aurora may be visible at high latitudes.

3-hour  K-indices for last 7 days ending 06:30 UTC, August 22, 2017

Over the past 36 hours, and before the sudden enhancement, solar wind parameters showed subsiding influences from a positive polarity coronal hole high speed stream (CH HSS). Total field strength mainly ranged between 2 and 5 nT, with an isolated bump to 9 nT, and the Bz component reached a maximum southward deflection of -6 nT. The phi angle remained in a mostly positive orientation, with brief deflections into the negative sector midday and late UTC, August 21.

The solar wind environment is expected to remain enhanced over the next two days (August 22 and 23) while solar wind speeds recover to background levels in the wake of CH HSS. Primarily normal conditions are expected by August 24 as solar wind parameters return to background levels, SWPC said.

The greater than 2 MeV electron flux reached very high levels with a peak flux of 52 000 pfu at 17:25 UTC on August 21 and is expected to remain at high to very high levels over the next three days. The greater than 10 MeV proton flux is at background levels and expected to remain at those levels over the next three days.

The geomagnetic field was expected to be at mostly quiet to unsettled levels on August 22, with isolated active periods early in the UTC day. However, due to a sudden enhancement in solar wind parameters, they increased to G1 - Minor levels 02:44 UTC, followed by a further increase to G2 - Moderate levels at 02:59 and back to G1 levels at 05:35 UTC.

Mostly quiet conditions with intermittent unsettled periods are expected on August 23. August 24 should see mostly quiet conditions.

SWPC alerts and warnings

Space Weather Message Code: ALTK05
Serial Number: 1138
Issue Time: 2017 Aug 22 0535 UTC

ALERT: Geomagnetic K-index of 5
Threshold Reached: 2017 Aug 22 0535 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: WARK05
Serial Number: 1382
Issue Time: 2017 Aug 22 0305 UTC

EXTENDED WARNING: Geomagnetic K-index of 5 expected
Extension to Serial Number: 1381
Valid From: 2017 Aug 22 0155 UTC
Now Valid Until: 2017 Aug 22 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 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: WARK04
Serial Number: 3285
Issue Time: 2017 Aug 22 0305 UTC

EXTENDED WARNING: Geomagnetic K-index of 4 expected
Extension to Serial Number: 3284
Valid From: 2017 Aug 21 2225 UTC
Now Valid Until: 2017 Aug 22 1200 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: ALTK06
Serial Number: 439
Issue Time: 2017 Aug 22 0303 UTC

ALERT: Geomagnetic K-index of 6
Threshold Reached: 2017 Aug 22 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: WARK06
Serial Number: 392
Issue Time: 2017 Aug 22 0256 UTC

WARNING: Geomagnetic K-Index of 6 expected
Valid From: 2017 Aug 22 0255 UTC
Valid To: 2017 Aug 22 0800 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.

***

Space Weather Message Code: ALTK05
Serial Number: 1137
Issue Time: 2017 Aug 22 0244 UTC

ALERT: Geomagnetic K-index of 5
Threshold Reached: 2017 Aug 22 0244 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: WARK05
Serial Number: 1381
Issue Time: 2017 Aug 22 0152 UTC

WARNING: Geomagnetic K-index of 5 expected
Valid From: 2017 Aug 22 0155 UTC
Valid To: 2017 Aug 22 0600 UTC
Warning Condition: Onset
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: ALTK04
Serial Number: 1996
Issue Time: 2017 Aug 22 0052 UTC

ALERT: Geomagnetic K-index of 4
Threshold Reached: 2017 Aug 22 0052 UTC
Synoptic Period: 0000-0300 UTC

Active Warning: Yes

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: WARK04
Serial Number: 3284
Issue Time: 2017 Aug 21 2226 UTC

WARNING: Geomagnetic K-index of 4 expected
Valid From: 2017 Aug 21 2225 UTC
Valid To: 2017 Aug 22 0600 UTC
Warning Condition: Onset

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.

Featured image: Aurora forecast at 03:30 UTC on August 22, 2017. Credit: NOAA/SWPC

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